Introduce a new time API

The old time API is based on erlang:now/0. The major issue with
erlang:now/0 is that it was intended to be used for so many
unrelated things. This tied these unrelated operations together
and unnecessarily caused performance, scalability as well as
accuracy, and precision issues for operations that do not need
to have such issues. The new API spreads different functionality
over multiple functions in order to improve on this.

The new API consists of a number of new BIFs:
- erlang:convert_time_unit/3
- erlang:monotonic_time/0
- erlang:monotonic_time/1
- erlang:system_time/0
- erlang:system_time/1
- erlang:time_offset/0
- erlang:time_offset/1
- erlang:timestamp/0
- erlang:unique_integer/0
- erlang:unique_integer/1
- os:system_time/0
- os:system_time/1

and a number of extensions of existing BIFs:
- erlang:monitor(time_offset, clock_service)
- erlang:system_flag(time_offset, finalize)
- erlang:system_info(os_monotonic_time_source)
- erlang:system_info(time_offset)
- erlang:system_info(time_warp_mode)
- erlang:system_info(time_correction)
- erlang:system_info(start_time)

See the "Time and Time Correction in Erlang" chapter of the
ERTS User's Guide for more information.

74 files changed, 7317 insertions, 1606 deletions

diff --git a/erts/aclocal.m4 b/erts/aclocal.m4
index d78025b0be..989f697201 100644
--- a/erts/aclocal.m4
+++ b/erts/aclocal.m4
@@ -724,6 +724,117 @@ esac
 ])# AC_C_DOUBLE_MIDDLE_ENDIAN
 
 
+AC_DEFUN(ERL_MONOTONIC_CLOCK,
+[
+  AC_CACHE_CHECK([for clock_gettime() with monotonic clock type], erl_cv_clock_gettime_monotonic,
+  [
+     for clock_type in CLOCK_HIGHRES CLOCK_MONOTONIC CLOCK_MONOTONIC_PRECISE; do
+       AC_TRY_COMPILE([
+#include <time.h>
+		      ],
+		      [
+    struct timespec ts;
+    long long result;
+    clock_gettime($clock_type,&ts);
+    result = ((long long) ts.tv_sec) * 1000000000LL + 
+    ((long long) ts.tv_nsec);
+		      ],
+		      erl_cv_clock_gettime_monotonic=$clock_type,
+		      erl_cv_clock_gettime_monotonic=no)
+       test $erl_cv_clock_gettime_monotonic = no || break
+     done
+  ])
+  
+  AC_CHECK_FUNC(clock_getres)
+
+  AC_CHECK_FUNC(gethrtime)
+  
+  AC_CACHE_CHECK([for mach clock_get_time()], erl_cv_mach_clock_get_time,
+  [
+     AC_TRY_COMPILE([
+#include <mach/clock.h>
+#include <mach/mach.h>
+			],
+	 		[
+    kern_return_t res;
+    clock_serv_t clk_srv;
+    mach_timespec_t time_spec;
+
+    host_get_clock_service(mach_host_self(), SYSTEM_CLOCK, &clk_srv);
+    res = clock_get_time(clk_srv, &time_spec);
+    mach_port_deallocate(mach_task_self(), clk_srv);
+    			],
+    			erl_cv_mach_clock_get_time=yes,
+			erl_cv_mach_clock_get_time=no)
+  ])
+  
+  case $erl_cv_clock_gettime_monotonic-$ac_cv_func_gethrtime-$erl_cv_mach_clock_get_time-$host_os in
+    *-*-*-win32)
+      erl_monotonic_clock_func=GetTickCount
+      ;;
+    CLOCK_*-*-*-linux*)
+      if test X$cross_compiling != Xyes; then
+        linux_kernel_vsn_=`uname -r`
+        case $linux_kernel_vsn_ in
+          [[0-1]].*|2.[[0-5]]|2.[[0-5]].*)
+            erl_monotonic_clock_func=times
+	    ;;
+          *)
+            erl_monotonic_clock_func=clock_gettime
+	    ;;
+        esac
+      else
+        case X$erl_xcomp_linux_clock_gettime_correction in
+          X)
+	    AC_MSG_WARN([result clock_gettime guessed because of cross compilation])
+            erl_monotonic_clock_func=clock_gettime
+	    ;;
+          Xyes|Xno)
+            if test $erl_xcomp_linux_clock_gettime_correction = yes; then
+              erl_monotonic_clock_func=clock_gettime
+            else
+              erl_monotonic_clock_func=times
+            fi
+	    ;;
+          *)
+            AC_MSG_ERROR([Bad erl_xcomp_linux_clock_gettime_correction value: $erl_xcomp_linux_clock_gettime_correction])
+	    ;;
+        esac
+      fi
+      ;;
+    no-no-no-linux*)
+      erl_monotonic_clock_func=times
+      ;;
+    CLOCK_*-*-*-*)
+      erl_monotonic_clock_func=clock_gettime
+      ;;
+    no-yes-*-*)
+      erl_monotonic_clock_func=gethrtime
+      ;;
+    no-no-yes-*)
+      erl_monotonic_clock_func=mach_clock_get_time
+      ;;
+    no-no-no-*)
+      erl_monotonic_clock_func=none
+      ;;
+  esac
+
+  erl_monotonic_clock_lib=
+  erl_monotonic_clock_id=
+  case $erl_monotonic_clock_func in
+    clock_gettime)
+      erl_monotonic_clock_id="$erl_cv_clock_gettime_monotonic"
+      AC_CHECK_LIB(rt, clock_gettime, [erl_monotonic_clock_lib="-lrt"])
+      ;;
+    mach_clock_get_time)
+      erl_monotonic_clock_id=SYSTEM_CLOCK
+      ;;
+    *)
+      ;;
+  esac
+ 
+])
+
 dnl ----------------------------------------------------------------------
 dnl
 dnl LM_CHECK_THR_LIB
@@ -1016,12 +1127,32 @@ AC_ARG_WITH(with_sparc_memory_order,
 LM_CHECK_THR_LIB
 ERL_INTERNAL_LIBS
 
+ERL_MONOTONIC_CLOCK
+
+case $erl_monotonic_clock_func in
+  clock_gettime)
+    AC_DEFINE(ETHR_HAVE_CLOCK_GETTIME_MONOTONIC, [1], [Define if you have a clock_gettime() with a monotonic clock])
+    ;;
+  mach_clock_get_time)
+    AC_DEFINE(ETHR_HAVE_MACH_CLOCK_GET_TIME, [1], [Define if you have a mach clock_get_time() with a monotonic clock])
+    ;;
+  gethrtime)
+    AC_DEFINE(ETHR_HAVE_GETHRTIME, [1], [Define if you have a monotonic gethrtime()])
+    ;;
+  *)
+    ;;
+esac
+
+if test "x$erl_monotonic_clock_id" != "x"; then
+    AC_DEFINE_UNQUOTED(ETHR_MONOTONIC_CLOCK_ID, [$erl_monotonic_clock_id], [Define to the monotonic clock id to use])
+fi
+
 ethr_have_native_atomics=no
 ethr_have_native_spinlock=no
 ETHR_THR_LIB_BASE="$THR_LIB_NAME"
 ETHR_THR_LIB_BASE_TYPE="$THR_LIB_TYPE"
 ETHR_DEFS="$THR_DEFS"
-ETHR_X_LIBS="$THR_LIBS $ERTS_INTERNAL_X_LIBS"
+ETHR_X_LIBS="$THR_LIBS $ERTS_INTERNAL_X_LIBS $erl_monotonic_clock_lib"
 ETHR_LIBS=
 ETHR_LIB_NAME=
 
@@ -1660,7 +1791,6 @@ AC_SUBST(ETHR_X86_SSE2_ASM)
 ])
 
 
-
 dnl ----------------------------------------------------------------------
 dnl
 dnl ERL_TIME_CORRECTION
@@ -1676,93 +1806,33 @@ dnl work...
 dnl
 
 AC_DEFUN(ERL_TIME_CORRECTION,
-[if test x$ac_cv_func_gethrtime = x; then
-  AC_CHECK_FUNC(gethrtime)
-fi
-if test x$clock_gettime_correction = xunknown; then
-	AC_TRY_COMPILE([#include <time.h>],
-			[struct timespec ts;
-     			 long long result;
-			 clock_gettime(CLOCK_MONOTONIC,&ts);
-                         result = ((long long) ts.tv_sec) * 1000000000LL + 
-			 ((long long) ts.tv_nsec);],
-			clock_gettime_compiles=yes,
-			clock_gettime_compiles=no)
-else
-	clock_gettime_compiles=no
-fi
-			
-
-AC_CACHE_CHECK([how to correct for time adjustments], erl_cv_time_correction,
 [
-case $clock_gettime_correction in
-    yes)
-	erl_cv_time_correction=clock_gettime;;	
-    no|unknown)
-	case $ac_cv_func_gethrtime in
-  	    yes)
-    		erl_cv_time_correction=hrtime ;;
-  	    no)
-    		case $host_os in
-        	    linux*)
-			case $clock_gettime_correction in
-			    unknown)
-				if test x$clock_gettime_compiles = xyes; then
-				    if test X$cross_compiling != Xyes; then
-				    	linux_kernel_vsn_=`uname -r`
-				    	case $linux_kernel_vsn_ in
-					    [[0-1]].*|2.[[0-5]]|2.[[0-5]].*)
-					    	erl_cv_time_correction=times ;;
-					    *)
-					    	erl_cv_time_correction=clock_gettime;;
-				    	esac
-				    else
-					case X$erl_xcomp_linux_clock_gettime_correction in
-					    X)
-						erl_cv_time_correction=cross;;
-					    Xyes|Xno)
-						if test $erl_xcomp_linux_clock_gettime_correction = yes; then
-						    erl_cv_time_correction=clock_gettime
-						else
-					    	    erl_cv_time_correction=times
-						fi;;
-					    *)
-						AC_MSG_ERROR([Bad erl_xcomp_linux_clock_gettime_correction value: $erl_xcomp_linux_clock_gettime_correction]);;
-					esac
-				    fi
-				else
-				    erl_cv_time_correction=times
-				fi
-				;;
-			     *)				
-        			erl_cv_time_correction=times ;;
-			esac
-			;;
-            	    *)
-        		erl_cv_time_correction=none ;;
-    		esac
-    		;;
-	esac
-	;;
-esac
-])
 
-xrtlib=""
-case $erl_cv_time_correction in
+ERL_MONOTONIC_CLOCK
+
+case $erl_monotonic_clock_func in
   times)
-    AC_DEFINE(CORRECT_USING_TIMES,[],
-	[Define if you do not have a high-res. timer & want to use times() instead])
+    AC_DEFINE(OS_MONOTONIC_TIME_USING_TIMES, [1], [Define if you want to implement erts_os_monotonic_time() using times()])
     ;;
-  clock_gettime|cross)
-    if test $erl_cv_time_correction = cross; then
-	erl_cv_time_correction=clock_gettime
-	AC_MSG_WARN([result clock_gettime guessed because of cross compilation])
-    fi
-    xrtlib="-lrt"
-    AC_DEFINE(GETHRTIME_WITH_CLOCK_GETTIME,[1],
-	[Define if you want to use clock_gettime to simulate gethrtime])
+  mach_clock_get_time)
+    AC_DEFINE(OS_MONOTONIC_TIME_USING_MACH_CLOCK_GET_TIME, [1], [Define if you want to implement erts_os_monotonic_time() using mach clock_get_time()])
+    ;;
+  clock_gettime)
+    AC_DEFINE(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME, [1], [Define if you want to implement erts_os_monotonic_time() using clock_gettime()])
+    ;;
+  gethrtime)
+    AC_DEFINE(OS_MONOTONIC_TIME_USING_GETHRTIME,  [1], [Define if you want to implement erts_os_monotonic_time() using gethrtime()])
+    ;;
+  *)
     ;;
 esac
+
+xrtlib="$erl_monotonic_clock_lib"
+if test "x$erl_monotonic_clock_id" != "x"; then
+    AC_DEFINE_UNQUOTED(MONOTONIC_CLOCK_ID_STR, ["$erl_monotonic_clock_id"], [Define as a string of monotonic clock id to use])
+    AC_DEFINE_UNQUOTED(MONOTONIC_CLOCK_ID, [$erl_monotonic_clock_id], [Define to monotonic clock id to use])
+fi
+
 dnl
 dnl Check if gethrvtime is working, and if to use procfs ioctl
 dnl or (yet to be written) write to the procfs ctl file.
@@ -1835,6 +1905,7 @@ case X$erl_xcomp_gethrvtime_procfs_ioctl in
 esac
 ])
 
+LIBRT=$xrtlib
 case $erl_gethrvtime in
   procfs_ioctl)
 	AC_DEFINE(HAVE_GETHRVTIME_PROCFS_IOCTL,[1],
@@ -1894,7 +1965,6 @@ case $erl_gethrvtime in
 	case $host_os in
 		linux*)
 			AC_MSG_RESULT([no; not stable])
-			LIBRT=$xrtlib
 			;;
 		*)
 			AC_MSG_RESULT($erl_clock_gettime)
@@ -1907,17 +1977,15 @@ case $erl_gethrvtime in
 	  			cross)
 					erl_clock_gettime=no
 					AC_MSG_WARN([result no guessed because of cross compilation])
-					LIBRT=$xrtlib
 					;;
 	  			*)
-					LIBRT=$xrtlib
 					;;
 			esac
 			;;
 	esac
-	AC_SUBST(LIBRT)
 	;;
 esac
+AC_SUBST(LIBRT)
 ])dnl
 
 dnl ----------------------------------------------------------------------
diff --git a/erts/autoconf/win32.config.cache.static b/erts/autoconf/win32.config.cache.static
index b387db2b22..b3328e5414 100755
--- a/erts/autoconf/win32.config.cache.static
+++ b/erts/autoconf/win32.config.cache.static
@@ -221,7 +221,6 @@ ac_cv_type_size_t=${ac_cv_type_size_t=yes}
 ac_cv_type_uid_t=${ac_cv_type_uid_t=no}
 ac_cv_type_void_p=${ac_cv_type_void_p=yes}
 ac_cv_working_alloca_h=${ac_cv_working_alloca_h=no}
-erl_cv_time_correction=${erl_cv_time_correction=none}
 erts_cv___after_morecore_hook_can_track_malloc=${erts_cv___after_morecore_hook_can_track_malloc=no}
 erts_cv_fwrite_unlocked=${erts_cv_fwrite_unlocked=no}
 erts_cv_have__end_symbol=${erts_cv_have__end_symbol=no}
diff --git a/erts/autoconf/win64.config.cache.static b/erts/autoconf/win64.config.cache.static
index a8a2bfb59c..c7d92c7000 100755
--- a/erts/autoconf/win64.config.cache.static
+++ b/erts/autoconf/win64.config.cache.static
@@ -262,7 +262,6 @@ ac_cv_type_signal=${ac_cv_type_signal=void}
 ac_cv_type_size_t=${ac_cv_type_size_t=yes}
 ac_cv_type_uid_t=${ac_cv_type_uid_t=no}
 ac_cv_working_alloca_h=${ac_cv_working_alloca_h=no}
-erl_cv_time_correction=${erl_cv_time_correction=none}
 erts_cv___after_morecore_hook_can_track_malloc=${erts_cv___after_morecore_hook_can_track_malloc=no}
 erts_cv_fwrite_unlocked=${erts_cv_fwrite_unlocked=no}
 erts_cv_have__end_symbol=${erts_cv_have__end_symbol=no}
diff --git a/erts/doc/src/Makefile b/erts/doc/src/Makefile
index e8b856c3ff..a83aa9b875 100644
--- a/erts/doc/src/Makefile
+++ b/erts/doc/src/Makefile
@@ -177,6 +177,8 @@ release_docs_spec: docs
 	$(INSTALL_DIR) "$(RELSYSDIR)/doc/html"
 	$(INSTALL_DATA) $(HTMLDIR)/* \
 		"$(RELSYSDIR)/doc/html"
+	$(INSTALL_DATA) $(ERL_TOP)/erts/example/time_compat.erl \
+		"$(RELSYSDIR)/doc/html"
 	$(INSTALL_DATA) $(INFO_FILE) "$(RELSYSDIR)"
 	$(INSTALL_DIR) "$(RELEASE_PATH)/man/man3"
 	$(INSTALL_DATA) $(MAN3DIR)/* "$(RELEASE_PATH)/man/man3"
diff --git a/erts/doc/src/erl.xml b/erts/doc/src/erl.xml
index d11f6b0c6d..19a8e1f789 100644
--- a/erts/doc/src/erl.xml
+++ b/erts/doc/src/erl.xml
@@ -495,24 +495,35 @@
           <c><![CDATA[werl]]></c>, not <c><![CDATA[erl]]></c> (<c><![CDATA[oldshell]]></c>). Note also that
           <c><![CDATA[Ctrl-Break]]></c> is used instead of <c><![CDATA[Ctrl-C]]></c> on Windows.</p>
       </item>
-      <tag><marker id="+c"><c><![CDATA[+c]]></c></marker></tag>
-      <item>
-        <p>Disable compensation for sudden changes of system time.</p>
-        <p>Normally, <c><![CDATA[erlang:now/0]]></c> will not immediately reflect
-          sudden changes in the system time, in order to keep timers
-          (including <c><![CDATA[receive-after]]></c>) working. Instead, the time
-          maintained by <c><![CDATA[erlang:now/0]]></c> is slowly adjusted towards
-          the new system time. (Slowly means in one percent adjustments;
-          if the time is off by one minute, the time will be adjusted
-          in 100 minutes.)</p>
-        <p>When the <c><![CDATA[+c]]></c> option is given, this slow adjustment
-          will not take place. Instead <c><![CDATA[erlang:now/0]]></c> will always
-          reflect the current system time. Note that timers are based
-          on <c><![CDATA[erlang:now/0]]></c>. If the system time jumps, timers
-          then time out at the wrong time.</p>
-        <p><em>NOTE</em>: You can check whether the adjustment is enabled or
-          disabled by calling
-	  <seealso marker="erlang#system_info_tolerant_timeofday">erlang:system_info(tolerant_timeofday)</seealso>.</p>
+      <tag><marker id="+c"><c><![CDATA[+c true | false]]></c></marker></tag>
+      <item>
+        <p>Enable or disable
+	<seealso marker="time_correction#Time_Correction">time correction</seealso>:</p>
+	<taglist>
+	  <tag><c>true</c></tag>
+	  <item><p>Enable time correction. This is the default if
+	  time correction is supported on the specific platform.</p></item>
+
+	  <tag><c>false</c></tag>
+	  <item><p>Disable time correction.</p></item>
+	</taglist>
+	<p>For backwards compatibility, the boolean value can be omitted.
+	This is interpreted as <c>+c false</c>.
+	</p>
+      </item>
+      <tag><marker id="+C_"><c><![CDATA[+C no_time_warp | single_time_warp | multi_time_warp]]></c></marker></tag>
+      <item>
+        <p>Set
+	<seealso marker="time_correction#Time_Warp_Modes">time warp mode</seealso>:
+	</p>
+	<taglist>
+	  <tag><c>no_time_warp</c></tag>
+	  <item><p><seealso marker="time_correction#No_Time_Warp_Mode">No Time Warp Mode</seealso> (the default)</p></item>
+	  <tag><c>single_time_warp</c></tag>
+	  <item><p><seealso marker="time_correction#Single_Time_Warp_Mode">Single Time Warp Mode</seealso></p></item>
+	  <tag><c>multi_time_warp</c></tag>
+	  <item><p><seealso marker="time_correction#Multi_Time_Warp_Mode">Multi Time Warp Mode</seealso></p></item>
+	</taglist>
       </item>
       <tag><c><![CDATA[+d]]></c></tag>
       <item>
diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index 483d81cfb6..3cbfd372ce 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -58,7 +58,71 @@
     </datatype>
     <datatype>
       <name name="timestamp"></name>
-      <desc><p>See <seealso marker="#now/0">now/0</seealso>.</p>
+      <desc><p>See <seealso marker="#timestamp/0">erlang:timestamp/0</seealso>.</p>
+      </desc>
+    </datatype>
+    <marker id="type_time_unit"/>
+    <datatype>
+      <name name="time_unit"></name>
+      <desc><p>Currently supported time unit representations:</p>
+        <taglist>
+	  <tag><c>PartsPerSecond :: integer() >= 1</c></tag>
+	  <item><p>Time unit expressed in parts per second. That is,
+	  the time unit equals <c>1/PartsPerSecond</c> second.</p></item>
+
+	  <tag><c>seconds</c></tag>
+	  <item><p>Symbolic representation of the time unit
+	  represented by the integer <c>1</c>.</p></item>
+
+	  <tag><c>milli_seconds</c></tag>
+	  <item><p>Symbolic representation of the time unit
+	  represented by the integer <c>1000</c>.</p></item>
+
+	  <tag><c>micro_seconds</c></tag>
+	  <item><p>Symbolic representation of the time unit
+	  represented by the integer <c>1000000</c>.</p></item>
+
+	  <tag><c>nano_seconds</c></tag>
+	  <item><p>Symbolic representation of the time unit
+	  represented by the integer <c>1000000000</c>.</p></item>
+
+	  <tag><c>native</c></tag>
+	  <item><p>Symbolic representation of the native time unit
+	  used by the Erlang runtime system.</p>
+
+	  <p>The <c>native</c> time unit is determined at
+	  runtime system start, and will remain the same until
+	  the runtime system terminates. If a runtime system
+	  is stopped and then started again (even on the same
+	  machine), the <c>native</c> time unit of the new
+	  runtime system instance may differ from the
+	  <c>native</c> time unit of the old runtime system
+	  instance.</p>
+
+	  <p>One can get an approximation of the <c>native</c>
+	  time unit by calling <c>erlang:convert_time_unit(1,
+	  seconds, native)</c>. The result equals the number
+	  of whole <c>native</c> time units per second. In case
+	  the number of <c>native</c> time units per second does
+	  not add up to a whole number, the result will be
+	  rounded downwards.</p>
+
+	  <note>
+	    <p>The value of the <c>native</c> time unit gives
+	    you more or less no information at all about the
+	    quality of time values. It sets an upper bound for
+	    the resolution as well as for the precision, but it
+	    gives absolutely no information at all about the
+	    accuracy.</p>
+	  </note>
+	  </item>
+
+	</taglist>
+
+	<p>The <c>time_unit/0</c> type may be extended. Use
+	<seealso marker="#convert_time_unit/3"><c>erlang:convert_time_unit/3</c></seealso>
+	in order to convert time values between time units.</p>
+
       </desc>
     </datatype>
   </datatypes>
@@ -585,6 +649,22 @@
       </desc>
     </func>
     <func>
+      <name name="convert_time_unit" arity="3"/>
+      <fsummary>Convert time unit of a time value</fsummary>
+      <desc>
+	<p>Converts the <c><anno>Time</anno></c> value of time unit
+	<c><anno>FromUnit</anno></c> to the corresponding
+	<c><anno>ConvertedTime</anno></c> value of time unit
+	<c><anno>ToUnit</anno></c>. The result is rounded
+	using the floor function.</p>
+
+	<warning><p>You may lose accuracy and precision when converting
+	between	time units. In order to minimize such loss, collect all
+	data at <c>native</c> time unit and do the conversion on the end
+	result.</p></warning>
+      </desc>
+    </func>
+    <func>
       <name name="crc32" arity="1"/>
       <fsummary>Compute crc32 (IEEE 802.3) checksum</fsummary>
       <desc>
@@ -2191,14 +2271,15 @@ os_prompt% </pre>
     </func>
     <func>
       <name name="make_ref" arity="0"/>
-      <fsummary>Return an almost unique reference</fsummary>
+      <fsummary>Return a unique reference</fsummary>
       <desc>
-        <p>Returns an almost unique reference.</p>
-        <p>The returned reference will re-occur after approximately 2^82
-          calls; therefore it is unique enough for practical purposes.</p>
-        <pre>
-> <input>make_ref().</input>
-#Ref&lt;0.0.0.135></pre>
+	<p>Return a <seealso marker="doc/efficiency_guide:advanced#unique_references">unique
+	reference</seealso>. The reference is unique among
+	connected nodes.</p>
+	<warning><p>Known issue: When a node is restarted multiple
+	times with the same node name, references created
+	on a newer node can be mistaken for a reference
+	created on an older node with the same node name.</p></warning>
       </desc>
     </func>
     <func>
@@ -2499,97 +2580,178 @@ os_prompt% </pre>
       </desc>
     </func>
     <func>
-      <name name="monitor" arity="2"/>
+      <name name="monitor" arity="2" clause_i="1"/>
+      <name name="monitor" arity="2" clause_i="2"/>
+      <type name="registered_name"/>
+      <type name="registered_process_identifier"/>
+      <type name="monitor_process_identifier"/>
       <fsummary>Start monitoring</fsummary>
       <desc>
-        <p>The calling process starts monitoring <c><anno>Item</anno></c> which is
-          an object of type <c><anno>Type</anno></c>.</p>
-        <p>Currently only processes can be monitored, i.e. the only
-          allowed <c><anno>Type</anno></c> is <c>process</c>, but other types may be
-          allowed in the future.</p>
-        <p><c><anno>Item</anno></c> can be:</p>
-        <taglist>
-          <tag><c>pid()</c></tag>
-          <item>
-            <p>The pid of the process to monitor.</p>
-          </item>
-          <tag><c>{RegName, Node}</c></tag>
-          <item>
-            <p>A tuple consisting of a registered name of a process and
-              a node name. The process residing on the node <c>Node</c>
-              with the registered name <c>RegName</c> will be monitored.</p>
-          </item>
-          <tag><c>RegName</c></tag>
-          <item>
-            <p>The process locally registered as <c>RegName</c> will be
-              monitored.</p>
-          </item>
-        </taglist>
-        <note>
-          <p>When a process is monitored by registered name, the process
-            that has the registered name at the time when
-            <c>monitor/2</c> is called will be monitored.
+	<p>Send a monitor request of type <c><anno>Type</anno></c> to the
+	entity identified by <c><anno>Item</anno></c>. The caller of
+	<c>monitor/2</c> will later be notified by a monitor message on the
+	following format if the monitored state is changed:</p>
+        <code type="none">{Tag, <anno>MonitorRef</anno>, <anno>Type</anno>, Object, Info}</code>
+	<note><p>The monitor request is an asynchronous signal. That is, it
+	takes time before the signal reach its destination.</p></note>
+	<p>Currently valid <c><anno>Type</anno></c>s:</p>
+	<taglist>
+	  <tag><marker id="monitor_process"/><c>process</c></tag>
+	  <item>
+	    <p>Monitor the existence of the process identified by
+	    <c><anno>Item</anno></c>. Currently valid
+	    <c><anno>Item</anno></c>s in combination with the
+	    <c>process <anno>Type</anno></c>:</p>
+            <taglist>
+              <tag><c>pid()</c></tag>
+              <item>
+		<p>The process identifier of the process to monitor.</p>
+              </item>
+              <tag><c>{RegisteredName, Node}</c></tag>
+              <item>
+		<p>A tuple consisting of a registered name of a process and
+		a node name. The process residing on the node <c>Node</c>
+		with the registered name <c>{RegisteredName, Node}</c> will
+		be monitored.</p>
+              </item>
+              <tag><c>RegisteredName</c></tag>
+              <item>
+		<p>The process locally registered as <c>RegisteredName</c>
+		will become monitored.</p>
+              </item>
+            </taglist>
+            <note><p>When a process is monitored by registered name, the
+	    process that has the registered name at the time when the
+            monitor request reach its destination will be monitored.
             The monitor will not be effected, if the registered name is
-            unregistered.</p>
-        </note>
-        <p>A <c>'DOWN'</c> message will be sent to the monitoring
-          process if <c><anno>Item</anno></c> dies, if <c><anno>Item</anno></c> does not exist,
-          or if the connection is lost to the node which <c><anno>Item</anno></c>
-          resides on. A <c>'DOWN'</c> message has the following pattern:</p>
-        <code type="none">
-{'DOWN', MonitorRef, Type, Object, Info}</code>
-        <p>where <c>MonitorRef</c> and <c>Type</c> are the same as
-          described above, and:</p>
-        <taglist>
-          <tag><c>Object</c></tag>
-          <item>
-            <p>A reference to the monitored object:</p>
-            <list type="bulleted">
-              <item>the pid of the monitored process, if <c><anno>Item</anno></c> was
-               specified as a pid.</item>
-              <item><c>{RegName, Node}</c>, if <c><anno>Item</anno></c> was specified as
-              <c>{RegName, Node}</c>.</item>
-              <item><c>{RegName, Node}</c>, if <c><anno>Item</anno></c> was specified as
-              <c>RegName</c>. <c>Node</c> will in this case be the
-               name of the local node (<c>node()</c>).</item>
-            </list>
-          </item>
-          <tag><c>Info</c></tag>
-          <item>
-            <p>Either the exit reason of the process, <c>noproc</c>
-              (non-existing process), or <c>noconnection</c> (no
-              connection to <c><anno>Node</anno></c>).</p>
-          </item>
-        </taglist>
-        <note>
-          <p>If/when <c>monitor/2</c> is extended (e.g. to
-            handle other item types than <c>process</c>), other
-            possible values for <c>Object</c>, and <c>Info</c> in the
-            <c>'DOWN'</c> message will be introduced.</p>
-        </note>
-        <p>The monitoring is turned off either when the <c>'DOWN'</c>
-          message is sent, or when
-          <seealso marker="#demonitor/1">demonitor/1</seealso>
-          is called.</p>
-        <p>If an attempt is made to monitor a process on an older node
-          (where remote process monitoring is not implemented or one
-          where remote process monitoring by registered name is not
-          implemented), the call fails with <c>badarg</c>.</p>
-        <p>Making several calls to <c>monitor/2</c> for the same
-          <c><anno>Item</anno></c> is not an error; it results in as many, completely
-          independent, monitorings.</p>
+            unregistered, or unregistered and later registered on another
+	    process.</p></note>
+	    <p>The monitor is triggered either when the monitored process
+	    terminates, is non existing, or if the connection to it is
+	    lost. In the case the connection to it is lost, we do not know
+	    if it still exist or not. After this type of monitor has been
+	    triggered, the monitor is automatically removed.</p>
+            <p>When the monitor is triggered a <c>'DOWN'</c> message will
+	    be sent to the monitoring process. A <c>'DOWN'</c> message has
+	    the following pattern:</p>
+            <code type="none">{'DOWN', MonitorRef, Type, Object, Info}</code>
+            <p>where <c>MonitorRef</c> and <c>Type</c> are the same as
+            described above, and:</p>
+            <taglist>
+              <tag><c>Object</c></tag>
+              <item>
+		<p>equals:</p>
+		<taglist>
+		  <tag><c><anno>Item</anno></c></tag>
+		  <item>If <c><anno>Item</anno></c> was specified by a
+		  pid.</item>
+		  <tag><c>{RegisteredName, Node}</c></tag>
+		  <item>If <c><anno>Item</anno></c> was specified as
+		  <c>RegisteredName</c>, or <c>{RegisteredName, Node}</c>
+		  where <c>Node</c> corresponds to the node that the
+		  monitored process resides on.</item>
+		</taglist>
+              </item>
+              <tag><c>Info</c></tag>
+              <item>
+		<p>Either the exit reason of the process, <c>noproc</c>
+		(non-existing process), or <c>noconnection</c> (no
+		connection to the node where the monitored process
+		resides).</p></item>
+	    </taglist>
+	    <p>The monitoring is turned off either when the <c>'DOWN'</c>
+	    message is sent, or when
+	    <seealso marker="#demonitor/1">demonitor/1</seealso>
+	    is called.</p>
+	    <p>If an attempt is made to monitor a process on an older node
+	    (where remote process monitoring is not implemented or one
+	    where remote process monitoring by registered name is not
+	    implemented), the call fails with <c>badarg</c>.</p>
+	    <note>
+	      <p>The format of the <c>'DOWN'</c> message changed in the 5.2
+	      version of the emulator (OTP release R9B) for monitor
+	      <em>by registered name</em>. The <c>Object</c> element of
+	      the <c>'DOWN'</c> message could in earlier versions
+	      sometimes be the pid of the monitored process and sometimes
+	      be the registered name. Now the <c>Object</c> element is
+	      always a tuple consisting of the registered name and
+	      the node name. Processes on new nodes (emulator version 5.2
+	      or greater) will always get <c>'DOWN'</c> messages on
+	      the new format even if they are monitoring processes on old
+	      nodes. Processes on old nodes will always get <c>'DOWN'</c>
+	      messages on the old format.</p>
+	    </note>
+	  </item>
+	  <tag><marker id="monitor_time_offset"/><c>time_offset</c></tag>
+	  <item>
+	    <p>Monitor changes in
+	    <seealso marker="#time_offset/0">time offset</seealso>
+	    between
+	    <seealso marker="time_correction#Erlang_Monotonic_Time">Erlang
+	    monotonic time</seealso> and
+	    <seealso marker="time_correction#Erlang_System_Time">Erlang
+	    system time</seealso>. There is only one valid
+	    <c><anno>Item</anno></c> in combination with the
+	    <c>time_offset <anno>Type</anno></c>, namely the atom
+	    <c>clock_service</c>. Note that the atom <c>clock_service</c> is
+	    <em>not</em> the registered name of a process. In this specific
+	    case it serves as an identifier of the runtime system internal
+	    clock service at current runtime system instance.</p>
+
+	    <p>The monitor is triggered when the time offset is changed.
+	    This either if the time offset value is changed, or if the
+	    offset is changed from preliminary to final during
+	    <seealso marker="#system_flag_time_offset">finalization
+	    of the time offset</seealso> when the
+	    <seealso marker="time_correction#Single_Time_Warp_Mode">single
+	    time warp mode</seealso> is used. When a change from preliminary
+	    to final time offset is made, the monitor will be triggered once
+	    regardless of whether the time offset value was changed due to
+	    the finalization or not.</p>
+
+	    <p>If the runtime system is in
+	    <seealso marker="time_correction#Multi_Time_Warp_Mode">multi
+	    time warp mode</seealso>, the time offset will be changed when
+	    the runtime system detects that the
+	    <seealso marker="time_correction#OS_System_Time">OS system
+	    time</seealso> has changed. The runtime system will, however,
+	    not detect this immediately when it happens. A task checking
+	    the time offset is scheduled to execute at least once a minute,
+	    so under normal operation this should be detected within a
+	    minute, but during heavy load it might take longer time.</p>
+
+	    <p>The monitor will <em>not</em> be automatically removed
+	    after it has been triggered. That is, repeated changes of
+	    the time offset will trigger the monitor repeatedly.</p>
+
+            <p>When the monitor is triggered a <c>'CHANGE'</c> message will
+	    be sent to the monitoring process. A <c>'CHANGE'</c> message has
+	    the following pattern:</p>
+            <code type="none">{'CHANGE', MonitorRef, Type, Item, NewTimeOffset}</code>
+            <p>where <c>MonitorRef</c>, <c><anno>Type</anno></c>, and 
+	    <c><anno>Item</anno></c> are the same as described above, and
+	    <c>NewTimeOffset</c> is the new time offset.</p>
+
+	    <p>When the <c>'CHANGE'</c> message has been received you are
+	    guaranteed not to retrieve the old time offset when calling
+	    <seealso marker="#time_offset/0"><c>erlang:time_offset()</c></seealso>.
+	    Note that you may observe the change of the time offset
+	    when calling <c>erlang:time_offset()</c> before you
+	    get the <c>'CHANGE'</c> message.</p>
+
+	  </item>
+	</taglist>
+	<p>Making several calls to <c>monitor/2</c> for the same
+	<c><anno>Item</anno></c> and/or <c><anno>Type</anno></c> is not
+	an error; it results in many, completely independent,
+	monitorings.</p>
+	<p>The monitor functionality is expected to be extended. That is,
+	other <c><anno>Type</anno></c>s and <c><anno>Item</anno></c>s
+	are expected to be supported in	the future.</p>
         <note>
-          <p>The format of the <c>'DOWN'</c> message changed in the 5.2
-            version of the emulator (OTP release R9B) for monitor <em>by registered name</em>. The <c>Object</c> element of
-            the <c>'DOWN'</c> message could in earlier versions
-            sometimes be the pid of the monitored process and sometimes
-            be the registered name. Now the <c>Object</c> element is
-            always a tuple consisting of the registered name and
-            the node name. Processes on new nodes (emulator version 5.2
-            or greater) will always get <c>'DOWN'</c> messages on
-            the new format even if they are monitoring processes on old
-            nodes. Processes on old nodes will always get <c>'DOWN'</c>
-            messages on the old format.</p>
+          <p>If/when <c>monitor/2</c> is extended, other
+            possible values for <c>Tag</c>, <c>Object</c>, and
+	    <c>Info</c> in the monitor message will be introduced.</p>
         </note>
       </desc>
     </func>
@@ -2640,6 +2802,51 @@ os_prompt% </pre>
       </desc>
     </func>
     <func>
+      <name name="monotonic_time" arity="0"/>
+      <fsummary>Current Erlang monotonic time</fsummary>
+      <desc>
+	<p>Returns the current
+	<seealso marker="time_correction#Erlang_Monotonic_Time">Erlang
+	monotonic time</seealso> in <c>native</c>
+	<seealso marker="#type_time_unit">time unit</seealso>. This
+	is a monotonically increasing time since some unspecified point in
+	time.</p>
+
+	<note><p>This is a
+	<seealso marker="time_correction#Monotonically_Increasing">monotonically increasing</seealso> time, but <em>not</em> a
+	<seealso marker="time_correction#Strictly_Monotonically_Increasing">strictly monotonically increasing</seealso>
+	time. That is, consecutive calls to
+	<c>erlang:monotonic_time/0</c> may produce the same result.</p>
+
+	<p>Different runtime system instances will use different
+	unspecified points in time as base for their Erlang monotonic clocks.
+	That is, it is <em>pointless</em> comparing monotonic times from
+	different runtime system instances. Different runtime system instances
+	may also place this unspecified point in time different relative
+	runtime system start. It may be placed in the future (time at start
+	will be a negative value), the past (time at start will be a
+	positive value), or the runtime system start (time at start will
+	be zero). The monotonic time as of runtime system start can be
+	retrieved by calling
+	<seealso marker="#system_info_start_time"><c>erlang:system_info(start_time)</c></seealso>.</p></note>
+      </desc>
+    </func>
+    <func>
+      <name name="monotonic_time" arity="1"/>
+      <fsummary>Current Erlang monotonic time</fsummary>
+      <desc>
+	<p>Returns the current
+	<seealso marker="time_correction#Erlang_Monotonic_Time">Erlang
+	monotonic time</seealso> converted
+	into the <c><anno>Unit</anno></c> passed as argument.</p>
+
+	<p>Same as calling
+	<seealso marker="#convert_time_unit/3"><c>erlang:convert_time_unit</c></seealso><c>(</c><seealso marker="#monotonic_time/0"><c>erlang:monotonic_time()</c></seealso><c>,
+	native, <anno>Unit</anno>)</c>
+	however optimized for commonly used <c><anno>Unit</anno></c>s.</p>
+      </desc>
+    </func>
+    <func>
       <name name="nif_error" arity="1"/>
       <fsummary>Stop execution with a given reason</fsummary>
       <desc>
@@ -2734,6 +2941,13 @@ os_prompt% </pre>
       <type name="timestamp"/>
       <fsummary>Elapsed time since 00:00 GMT</fsummary>
       <desc>
+	<warning><p><em>This function is deprecated! Do not use it!</em>
+	See the users guide chapter
+	<seealso marker="time_correction">Time and Time Correction</seealso>
+	for more information. Specifically the 
+	<seealso marker="time_correction#Dos_and_Donts">Dos and Dont's</seealso>
+	section for information on what to use instead of <c>erlang:now/0</c>.
+	</p></warning>
         <p>Returns the tuple <c>{MegaSecs, Secs, MicroSecs}</c> which is
           the elapsed time since 00:00 GMT, January 1, 1970 (zero hour)
           on the assumption that the underlying OS supports this.
@@ -2746,10 +2960,6 @@ os_prompt% </pre>
         <p>It can only be used to check the local time of day if
           the time-zone info of the underlying operating system is
           properly configured.</p>
-        <p>If you do not need the return value to be unique and
-          monotonically increasing, use
-          <seealso marker="kernel:os#timestamp/0">os:timestamp/0</seealso>
-          instead to avoid some overhead.</p>
       </desc>
     </func>
     <func>
@@ -5496,6 +5706,35 @@ ok
         <p>Returns the old value of the flag.</p>
       </desc>
     </func>
+    <marker id="system_flag_time_offset"/>
+    <func>
+      <name name="system_flag" arity="2" clause_i="12"/>
+      <fsummary>Finalize the Time Offset</fsummary>
+      <desc>
+        <p>Finalizes the <seealso marker="#time_offset/0">time offset</seealso>
+	when the <seealso marker="time_correction#Single_Time_Warp_Mode">single
+	time warp mode</seealso> is being used. If another time warp mode than
+	the "single time warp mode" is used, the time offset state will be left
+	unchanged.</p>
+        <p>Returns the old state identifier. That is, if:</p>
+	<list>
+	  <item><p><c>preliminary</c> is returned, finalization was
+	  performed and the time offset is now final.</p></item>
+
+	  <item><p><c>final</c> is returned, the time offset was
+	  already in the final state. This either due to another
+	  <c>erlang:system_flag(time_offset, finalize)</c> call, or
+	  due to the
+	  <seealso marker="time_correction#No_Time_Warp_Mode">no
+	  time warp mode</seealso> being used.</p></item>
+
+	  <item><p><c>volatile</c> is returned, the time offset
+	  cannot be finalized due to the 
+	  <seealso marker="time_correction#Multi_Time_Warp_Mode">multi
+	  time warp mode</seealso> being used.</p></item>
+	</list>
+      </desc>
+    </func>
     <func>
       <name name="system_info" arity="1" clause_i="1"/>
       <name name="system_info" arity="1" clause_i="2"/>
@@ -5776,6 +6015,15 @@ ok
       <name name="system_info" arity="1" clause_i="53"/>
       <name name="system_info" arity="1" clause_i="54"/>
       <name name="system_info" arity="1" clause_i="55"/>
+      <name name="system_info" arity="1" clause_i="56"/>
+      <name name="system_info" arity="1" clause_i="57"/>
+      <name name="system_info" arity="1" clause_i="58"/>
+      <name name="system_info" arity="1" clause_i="59"/>
+      <name name="system_info" arity="1" clause_i="60"/>
+      <name name="system_info" arity="1" clause_i="61"/>
+      <name name="system_info" arity="1" clause_i="62"/>
+      <name name="system_info" arity="1" clause_i="63"/>
+      <name name="system_info" arity="1" clause_i="64"/>
       <fsummary>Information about the system</fsummary>
       <desc>
         <p>Returns various information about the current system
@@ -6163,6 +6411,57 @@ ok
 	    documentation of versions in the system principles
 	    guide</seealso>.</p>
           </item>
+          <tag><marker id="system_info_os_monotonic_time_source"><c>os_monotonic_time_source</c></marker></tag>
+          <item>
+            <p>Returns a list containing information about the source of
+	    <seealso marker="erts:time_correction#OS_Monotonic_Time">OS
+	    monotonic time</seealso> that is used by the runtime system.</p>
+	    <p>In case <c>[]</c> is returned, no OS monotonic time is
+	    available. The list contains two-tuples with <c>Key</c>s
+	    as first element, and <c>Value</c>s as second element. The
+	    order if these tuples is undefined. Currently the following
+	    tuples may be part of the list, but more tuples may be
+	    introduced in the future:</p>
+	    <taglist>
+	      <tag><c>{function, Function}</c></tag>
+	      <item><p><c>Function</c> is the name of the funcion
+	      used. This tuple always exist if OS monotonic time is
+	      available to the runtime system.</p></item>
+
+	      <tag><c>{clock_id, ClockId}</c></tag>
+	      <item><p>This tuple only exist if <c>Function</c>
+	      can be used with different clocks. <c>ClockId</c>
+	      corresponds to the clock identifer used when calling
+	      <c>Function</c>.</p></item>
+
+	      <tag><c>{resolution, OsMonotonicTimeResolution}</c></tag>
+	      <item><p>Highest possible resolution of current
+	      OS monotonic time source as parts per second. If
+	      no resolution information can be retreived from
+	      the OS, <c>OsMonotonicTimeResolution</c> will be
+	      set to the resolution of the time unit of
+	      <c>Function</c>s return value. That is, the actual
+	      resolution may be lower than
+	      <c>OsMonotonicTimeResolution</c>. Also note that
+	      the resolution does not say anything about the
+	      accuracy, and that the precision might not align
+	      with the resolution. You do, however, know that the
+	      precision won't be higher than
+	      <c>OsMonotonicTimeResolution</c>.</p></item>
+
+	      <tag><c>{parallel, Parallel}</c></tag>
+	      <item><p><c>Parallel</c> equals <c>yes</c> if
+	      <c>Function</c> is called in parallel from multiple
+	      threads. If it is not called in parallel, because
+	      calls needs to be serialized, <c>Parallel</c> equals
+	      <c>no</c>.</p></item>
+
+	      <tag><c>{time, OsMonotonicTime}</c></tag>
+	      <item><p><c>OsMonotonicTime</c> equals current OS
+	      monotonic time in <c>native</c>
+	      <seealso marker="#type_time_unit">time unit</seealso>.</p></item>
+	    </taglist>
+          </item>
 	  <tag><marker id="system_info_port_parallelism"><c>port_parallelism</c></marker></tag>
 	  <item><p>Returns the default port parallelism scheduling hint used.
 	  For more information see the
@@ -6288,6 +6587,11 @@ ok
             <p>Returns <c>true</c> if the emulator has been compiled
               with smp support; otherwise, <c>false</c>.</p>
           </item>
+	  <tag><marker id="system_info_start_time"/><c>start_time</c></tag>
+	  <item><p>The <seealso marker="#monotonic_time/0">Erlang monotonic
+	  time</seealso> in <c>native</c>
+	  <seealso marker="#type_time_unit">time unit</seealso> at the
+	  time when current Erlang runtime system instance started.</p></item>
           <tag><c>system_version</c></tag>
           <item>
             <p>Returns a string containing version number and
@@ -6311,12 +6615,64 @@ ok
               (<seealso marker="erts:erl_driver#driver_async">driver_async()</seealso>)
               as an integer.</p>
           </item>
+	  <tag><marker id="system_info_time_correction"/><c>time_correction</c></tag>
+	  <item><p>Returns a boolean value indicating whether
+	  <seealso marker="time_correction#Time_Correction">time correction</seealso>
+	  is enabled or not.
+	  </p></item>
+	  <tag><marker id="system_info_time_offset"/><c>time_offset</c></tag>
+	  <item><p>Returns the state of the time offset:</p>
+	  <taglist>
+	    <tag><c>preliminary</c></tag>
+	    <item><p>The time offset is preliminary, and will be changed
+	    at a later time when being finalized. The preliminary time offset
+	    is used during the preliminary phase of the
+	    <seealso marker="time_correction#Single_Time_Warp_Mode">single
+	    time warp mode</seealso>.</p></item>
+
+	    <tag><c>final</c></tag>
+	    <item><p>The time offset is final. This
+	    either due to the use of the
+	    <seealso marker="time_correction#No_Time_Warp_Mode">no
+	    time warp mode</seealso>, or due to the time offset having
+	    been finalized when using the
+	    <seealso marker="time_correction#Single_Time_Warp_Mode">single
+	    time warp mode</seealso>.</p></item>
+
+	    <tag><c>volatile</c></tag>
+	    <item><p>The time offset is volatile. That is, it may
+	    change at any time. This due to the
+	    <seealso marker="time_correction#Multi_Time_Warp_Mode">multi
+	    time warp mode</seealso> being used.</p></item>
+	  </taglist>
+	  </item>
+	  <tag><marker id="system_info_time_warp_mode"/><c>time_warp_mode</c></tag>
+	  <item><p>Returns a value identifying the
+	  <seealso marker="time_correction#Time_Warp_Modes">time warp
+	  mode</seealso> being used:</p>
+	  <taglist>
+	    <tag><c>no_time_warp</c></tag>
+	    <item><p>The <seealso marker="time_correction#No_Time_Warp_Mode">no
+	    time warp mode</seealso> is being used.</p></item>
+
+	    <tag><c>single_time_warp</c></tag>
+	    <item><p>The <seealso marker="time_correction#Single_Time_Warp_Mode">single
+	    time warp mode</seealso> is being used.</p></item>
+
+	    <tag><c>multi_time_warp</c></tag>
+	    <item><p>The <seealso marker="time_correction#Multi_Time_Warp_Mode">multi
+	    time warp mode</seealso> is being used.</p></item>
+	  </taglist>
+	  </item>
           <tag><marker id="system_info_tolerant_timeofday"><c>tolerant_timeofday</c></marker></tag>
           <item>
-            <p>Returns whether compensation for sudden changes of system
-              time is <c>enabled</c> or <c>disabled</c>.</p>
-            <p>See also <seealso marker="erts:erl#+c">+c</seealso>
-              command line flag.</p>
+            <p>Returns whether a pre erts-7.0 backwards compatible compensation
+	    for sudden changes of system time is <c>enabled</c> or <c>disabled</c>.
+	    Such compensation is <c>enabled</c> when the
+	    <seealso marker="#system_info_time_offset">time offset</seealso> is
+	    <c>final</c>, and
+	    <seealso marker="#system_info_time_correction">time correction</seealso>
+	    is enabled.</p>
           </item>
           <tag><c>trace_control_word</c></tag>
           <item>
@@ -6595,7 +6951,44 @@ ok
         </note>
       </desc>
     </func>
+    <func>
+      <name name="system_time" arity="0"/>
+      <fsummary>Current Erlang system time</fsummary>
+      <desc>
+	<p>Returns current
+	<seealso marker="time_correction#Erlang_System_Time">Erlang system time</seealso>
+	in <c>native</c>
+	<seealso marker="#type_time_unit">time unit</seealso>.</p>
 
+	<p>Calling <c>erlang:system_time()</c> is equivalent to: 
+	<seealso marker="#monotonic_time/0"><c>erlang:monotonic_time()</c></seealso><c>
+	+
+        </c><seealso marker="#time_offset/0"><c>erlang:time_offset()</c></seealso>.</p>
+
+	<note><p>This time is <em>not</em> a monotonically increasing time
+	in the general case. For more information, see the documentation of
+	<seealso marker="time_correction#Time_Warp_Modes">time warp modes</seealso> in the
+	ERTS User's Guide.</p></note>
+      </desc>
+    </func>
+    <func>
+      <name name="system_time" arity="1"/>
+      <fsummary>Current Erlang system time</fsummary>
+      <desc>
+	<p>Returns current
+	<seealso marker="time_correction#Erlang_System_Time">Erlang system time</seealso>
+	converted into the <c><anno>Unit</anno></c> passed as argument.</p>
+
+	<p>Calling <c>erlang:system_time(<anno>Unit</anno>)</c> is equivalent to: 
+	<seealso marker="#convert_time_unit/3"><c>erlang:convert_time_unit</c></seealso><c>(</c><seealso marker="#system_time/0"><c>erlang:system_time()</c></seealso><c>,
+	native, <anno>Unit</anno>)</c>.</p>
+
+	<note><p>This time is <em>not</em> a monotonically increasing time
+	in the general case. For more information, see the documentation of
+	<seealso marker="time_correction#Time_Warp_Modes">time warp modes</seealso> in the
+	ERTS User's Guide.</p></note>
+      </desc>
+    </func>
     <func>
       <name name="term_to_binary" arity="1"/>
       <fsummary>Encode a term to an Erlang external term format binary</fsummary>
@@ -6672,6 +7065,88 @@ ok
       </desc>
     </func>
     <func>
+      <name name="time_offset" arity="0"/>
+      <fsummary>Current time offset</fsummary>
+      <desc>
+	<p>Returns the current time offset between
+	<seealso marker="time_correction#Erlang_Monotonic_Time">Erlang monotonic time</seealso>
+	and
+	<seealso marker="time_correction#Erlang_System_Time">Erlang system time</seealso> in
+	<c>native</c> <seealso marker="#type_time_unit">time unit</seealso>.
+	Current time offset added to an Erlang monotonic time gives
+	corresponding Erlang system time.</p>
+
+	<p>The time offset may or may not change during operation depending
+	on the <seealso marker="time_correction#Time_Warp_Modes">time
+	warp mode</seealso> used.</p>
+
+	<note>
+	  <p>A change in time offset may be observed at slightly
+	  different points in time by different processes.</p>
+
+	  <p>If the runtime system is in
+	  <seealso marker="time_correction#Multi_Time_Warp_Mode">multi
+	  time warp mode</seealso>, the time offset will be changed when
+	  the runtime system detects that the
+	  <seealso marker="time_correction#OS_System_Time">OS system
+	  time</seealso> has changed. The runtime system will, however,
+	  not detect this immediately when it happens. A task checking
+	  the time offset is scheduled to execute at least once a minute,
+	  so under normal operation this should be detected within a
+	  minute, but during heavy load it might take longer time.</p>
+	</note>
+      </desc>
+    </func>
+    <func>
+      <name name="time_offset" arity="1"/>
+      <fsummary>Current time offset</fsummary>
+      <desc>
+	<p>Returns the current time offset between
+	<seealso marker="time_correction#Erlang_Monotonic_Time">Erlang monotonic time</seealso>
+	and
+	<seealso marker="time_correction#Erlang_System_Time">Erlang system time</seealso>
+	converted into the <c><anno>Unit</anno></c> passed as argument.</p>
+
+	<p>Same as calling	
+	<seealso marker="#convert_time_unit/3"><c>erlang:convert_time_unit</c></seealso><c>(</c><seealso marker="#time_offset/0"><c>erlang:time_offset()</c></seealso><c>, native, <anno>Unit</anno>)</c>
+	however optimized for commonly used <c><anno>Unit</anno></c>s.</p>
+      </desc>
+    </func>
+    <func>
+      <name name="timestamp" arity="0"/>
+      <type name="timestamp"/>
+      <fsummary>Current Erlang System time</fsummary>
+      <desc>
+	<p>Returns current
+	<seealso marker="time_correction#Erlang_System_Time">Erlang system time</seealso>
+	on the format <c>{MegaSecs, Secs, MicroSecs}</c>. This format is 
+	the same that <seealso marker="kernel:os#timestamp/0"><c>os:timestamp/0</c></seealso>
+	and the now deprecated <seealso marker="#now/0"><c>erlang:now/0</c></seealso>
+	uses. The reason for the existence of <c>erlang:timestamp()</c> is
+	purely to simplify usage for existing code that assumes this timestamp
+	format. Current Erlang system time can more efficiently be retrieved in
+	the time unit of your choice using
+	<seealso marker="#system_time/1"><c>erlang:system_time/1</c></seealso>.</p>
+
+	<p>The <c>erlang:timestamp()</c> BIF is equivalent to:</p><code type="none">
+timestamp() ->
+    ErlangSystemTime = erlang:system_time(micro_seconds),
+    MegaSecs = ErlangSystemTime div 1000000000000,
+    Secs = ErlangSystemTime div 1000000 - MegaSecs*1000000,
+    MicroSecs = ErlangSystemTime rem 1000000,
+    {MegaSecs, Secs, MicroSecs}.</code>
+        <p>It however use a native implementation which does
+	not build garbage on the heap and with slightly better
+	performance.</p>
+
+	<note><p>This time is <em>not</em> a monotonically increasing time
+	in the general case. For more information, see the documentation of
+	<seealso marker="time_correction#Time_Warp_Modes">time warp modes</seealso> in the
+	ERTS User's Guide.</p></note>
+      </desc>
+
+    </func>
+    <func>
       <name name="tl" arity="1"/>
       <fsummary>Tail of a list</fsummary>
       <desc>
@@ -7436,6 +7911,100 @@ ok
       </desc>
     </func>
     <func>
+      <name name="unique_integer" arity="0"/>
+      <fsummary>Get a unique integer value</fsummary>
+      <desc>
+	<p>Generates and returns an
+	<seealso marker="doc/efficiency_guide:advanced#unique_integers">integer
+	unique on current runtime system instance</seealso>. The same as calling
+	<seealso marker="#unique_integer/1"><c>erlang:unique_integer([])</c></seealso>.</p>
+      </desc>
+    </func>
+    <func>
+      <name name="unique_integer" arity="1"/>
+      <fsummary>Get a unique integer value</fsummary>
+      <desc>
+	<p>Generates and returns an
+	<seealso marker="doc/efficiency_guide:advanced#unique_integers">integer
+	unique on current runtime system
+	instance</seealso>. The integer is unique in the
+	sense that this BIF, using the same set of
+	modifiers, will not return the same integer more
+	than once on the current runtime system instance.
+	Each integer value can of course be constructed
+	by other means.</p>
+
+	<p>By default, i.e. when <c>[]</c> is passed as
+	<c><anno>ModifierList</anno></c>, both negative and
+	positive integers will be returned. This is order
+	to be able to utilize the range of integers that do
+	not need to be heap allocated as much as possible.
+	By default the returned integers are also only
+	guaranteed to be unique, i.e., any integer returned
+	may be either smaller, or larger than previously
+	returned integers.</p>
+
+	<p>Currently valid <c><anno>Modifier</anno></c>s:</p>
+	<taglist>
+
+	  <tag>positive</tag>
+	  <item><p>Return only positive integers.</p>
+	  <p>Note that by passing the <c>positive</c> modifier
+	  you will get heap allocated integers (big-nums)
+	  quicker.</p>
+	  </item>
+
+	  <tag>monotonic</tag>
+	  <item><p>Return
+	  <seealso marker="time_correction#Strictly_Monotonically_Increasing">strictly
+	  monotonically increasing</seealso> integers
+	  corresponding to creation time. That is, the integer
+	  returned will always be larger than previously
+	  returned integers on the current runtime system
+	  instance.</p>
+	  <p>These values can be used when ordering events
+	  on the runtime system instance. That is, if both
+	  <c>X = erlang:unique_integer([monotonic])</c> and
+	  <c>Y = erlang:unique_integer([monotonic])</c> are
+	  executed by different processes (or the same
+	  process) on the same runtime system instance and
+	  <c>X &lt; Y</c> we know that <c>X</c> was created
+	  before <c>Y</c>.</p>
+	  <warning><p>Strictly monotonically increasing values
+	  are inherently quite expensive to generate and scales
+	  poorly. This since the values needs to be
+	  synchronized. That is, do not pass the <c>monotonic</c>
+	  modifier unless you really need strictly monotonically
+	  increasing values.</p></warning>
+	  </item>
+
+	</taglist>
+
+	<p>All currently valid <c><anno>Modifier</anno></c>s
+	can be combined. Repeated (valid)
+	<c><anno>Modifier</anno></c>s in the <c>ModifierList</c>
+	are ignored.</p>
+
+	<note><p>Note that the set of integers returned by
+	<c>unique_integer/1</c> using diffrent sets of
+	<c><anno>Modifier</anno></c>s <em>will overlap</em>.
+	For example, by calling	<c>unique_integer([monotonic])</c>,
+	and <c>unique_integer([positive, monotonic])</c>
+	repeatedly, you will eventually see some integers being
+	returned by both calls.</p></note>
+
+        <p>Failures:</p>
+	<taglist>
+	  <tag><c>badarg</c></tag>
+	  <item>if <c><anno>ModifierList</anno></c> is not a
+	  proper list.</item>
+	  <tag><c>badarg</c></tag>
+	  <item>if <c><anno>Modifier</anno></c> is not a
+	  valid modifier.</item>
+	</taglist>
+      </desc>
+    </func>
+    <func>
       <name name="unlink" arity="1"/>
       <fsummary>Remove a link, if there is one, to another process or port</fsummary>
       <desc>
diff --git a/erts/doc/src/time_correction.xml b/erts/doc/src/time_correction.xml
index 7f7c28fc30..3bc3d04186 100644
--- a/erts/doc/src/time_correction.xml
+++ b/erts/doc/src/time_correction.xml
@@ -21,8 +21,8 @@
 
     </legalnotice>
 
-    <title>Time and time correction in Erlang</title>
-    <prepared>Patrik Nyblom</prepared>
+    <title>Time and Time Correction in Erlang</title>
+    <prepared></prepared>
     <responsible></responsible>
     <docno></docno>
     <approved></approved>
@@ -31,6 +31,176 @@
     <rev>PA1</rev>
     <file>time_correction.xml</file>
   </header>
+
+  <section>
+    <title>New Extended Time Functionality</title>
+    <note><p>As of OTP 18 (ERTS version 7.0) the time functionality of
+    Erlang has been extended. This both includes a
+    <seealso marker="#The_New_Time_API">new API</seealso>
+    for time, as well as
+    <seealso marker="#Time_Warp_Modes">time warp
+    modes</seealso> which alters the behavior of the system when
+    system time changes.</p>
+    <p>The <seealso marker="#No_Time_Warp_Mode">default
+    time warp mode</seealso> has the same behavior as before, and the
+    old API will still work, so you are not required to change
+    anything unless you want to. However, <em>you are strongly
+    encouraged to use the new API</em> instead of the old API based
+    on <seealso marker="erlang#now/0"><c>erlang:now/0</c></seealso>.
+    <c>erlang:now/0</c> has been deprecated since it is and forever
+    will be a scalability bottleneck. By using the new API you will
+    automatically get scalability and performance improvements. This
+    will also enable you to use the
+    <seealso marker="#Multi_Time_Warp_Mode">multi time warp mode</seealso>
+    which improves accuracy, and precision of time measurements.</p></note>
+  </section>
+
+  <section>
+    <title>Some Terminology</title>
+    <p>In order to make it easier to understand this document we first
+    define some terminology. This is a mixture of our own terminology
+    (Erlang/OS system time, Erlang/OS monotonic time, time warp)
+    and globally accepted terminology.</p>
+
+    <marker id="Monotonically_Increasing"/>
+    <section>
+      <title>Monotonically Increasing</title>
+      <p>In a monotonically increasing sequence of values, all values
+      that have a predecessor are either larger than, or equal to its
+      predecessor.</p>
+    </section>
+
+    <marker id="Strictly_Monotonically_Increasing"/>
+    <section>
+      <title>Strictly Monotonically Increasing</title>
+      <p>In a strictly monotonically increasing sequence of values,
+      all values that have a predecessor are larger than its
+      predecessor.</p>
+    </section>
+
+    <marker id="UT1"/>
+    <section>
+      <title>UT1</title>
+      <p>Universal Time. Based on the rotation of the earth. Conceptually
+      mean solar time at 0° longitude.</p>
+    </section>
+
+    <marker id="UTC"/>
+    <section>
+      <title>UTC</title>
+      <p>Coordinated Universal Time. UTC almost align with
+      <seealso marker="#UT1">UT1</seealso>, however, UTC uses the
+      SI definition of a second which is not exactly of the same length
+      as the second used by UT1. This means that UTC slowly drifts from
+      UT1. In order to keep UTC relatively in sync with UT1, leap seconds
+      are inserted, and potentially also deleted. That is, an UTC day may
+      be 86400, 86401, or 86399 seconds long.</p>
+    </section>
+
+    <marker id="POSIX_Time"/>
+    <section>
+      <title>POSIX Time</title>
+      <p>Time since
+      <url href="http://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_xbd_chap03.html#tag_21_03_00_17">Epoch</url>.
+      Epoch is defined to be 00:00:00 <seealso marker="#UTC">UTC</seealso>,
+      January 1, 1970.
+      <url href="http://pubs.opengroup.org/onlinepubs/009604499/basedefs/xbd_chap04.html#tag_04_14">A day in POSIX time</url>
+      is defined to be exactly 86400 seconds long. Strangely enough
+      Epoch is defined to be a time in UTC, and UTC have another
+      definition of how long a day is. Quoting the Open Group
+      <url href="http://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_xbd_chap04.html#tag_21_04_15">"POSIX time is therefore not necessarily UTC, despite its appearance"</url>. The effect of this is that when an UTC leap second is
+      inserted, POSIX time either stops for a second, or repeats the
+      last second. If an UTC leap second would be deleted (has never
+      happened yet), POSIX time would make a one second leap forward.</p>
+    </section>
+
+    <marker id="OS_System_Time"/>
+    <section>
+      <title>OS System Time</title>
+      <p>The operating systems view of
+      <seealso marker="#POSIX_Time">POSIX time</seealso>. It can be
+      retrieved by calling
+      <seealso marker="kernel:os#system_time/0"><c>os:system_time()</c></seealso>.
+      This may or may not be an accurate view of POSIX time. This time
+      may typically be adjusted both backwards and forwards without
+      limitation. That is, huge leaps both backwards and forwards in time
+      may be observed.</p>
+    </section>
+
+    <marker id="OS_Monotonic_Time"/>
+    <section>
+      <title>OS Monotonic Time</title>
+      <p>A monotonically increasing time provided by the operating
+      system. This time does not leap and have a relatively steady
+      frequency although not completely correct. However, it is not
+      uncommon that the OS monotonic time stops if the system is
+      suspended. This time typically increase since some unspecified
+      point in time that is not connected to
+      <seealso marker="#OS_System_Time">OS system time</seealso>. Note that
+      this type of time is not necessarily provided by all operating
+      systems.</p>
+    </section>
+
+    <marker id="Erlang_System_Time"/>
+    <section>
+      <title>Erlang System Time</title>
+      <p>The Erlang runtime systems view of
+      <seealso marker="#POSIX_Time">POSIX time</seealso>. It can be
+      retrieved by calling
+      <seealso marker="erlang#system_time/0"><c>erlang:system_time()</c></seealso>.
+      This time may or may not be an accurate view of POSIX time, and may
+      or may not align with <seealso marker="#OS_System_Time">OS system
+      time</seealso>.  The <seealso marker="#Time_Warp_Modes">time
+      warp mode</seealso> determines how it behaves when OS system
+      time suddenly change.</p>
+    </section>
+
+    <marker id="Erlang_Monotonic_Time"/>
+    <section>
+      <title>Erlang Monotonic Time</title>
+      <p>A monotonically increasing time provided by the
+      Erlang runtime system. The Erlang monotonic time increase since
+      some unspecified point in time. It can be retrieved by calling
+      <seealso marker="erlang#monotonic_time/0"><c>erlang:monotonic_time()</c></seealso>.
+      The accuracy, and precision of Erlang monotonic time heavily
+      depends on the accuracy and precision of
+      <seealso marker="#OS_Monotonic_Time">OS monotonic time</seealso>,
+      the accuracy and precision of
+      <seealso marker="#OS_System_Time">OS system time</seealso> as well
+      as on the
+      <seealso marker="#Time_Warp_Modes">time warp mode</seealso>
+      used. On a system that is lacking OS monotonic time, the Erlang
+      monotonic time can only guarantee monotonicity and can more or less
+      not give any other guarantees. The frequency adjustments made to
+      the Erlang monotonic time depends on the time warp mode
+      used.</p>
+
+      <p>Internally in the runtime system the Erlang monotonic
+      time is the "time engine" that is used for more or less
+      everything that has anything to do with time. All timers
+      regardless of it is a <c>receive ... after</c> timer, BIF timer,
+      or a timer in the <c>timer</c> module are triggered
+      relative Erlang monotonic time. Even
+      <seealso marker="#Erlang_System_Time">Erlang system
+      time</seealso> is based on Erlang monotonic time.
+      By adding current Erlang monotonic time with current time
+      offset you get current Erlang system time. Current time
+      offset can be retrieved by calling
+      <seealso marker="erlang#time_offset/0"><c>erlang:time_offset/0</c></seealso>.
+      </p>
+    </section>
+
+    <marker id="Time_Warp"/>
+    <section>
+      <title>Time Warp</title>
+      <p>A time warp is a leap forwards or backwards in time.</p>
+    </section>
+
+  </section>
+
+  <section>
+    <title>Introduction</title>
+
   <p>Time is vital to an Erlang program and, more importantly, <em>correct</em>
   time is vital to an Erlang program. As Erlang is a language with
   soft real time properties and we have the possibility to express
@@ -83,192 +253,587 @@
   microsecond resolution or much less, but generally it has a drift
   that is not to be ignored.</p>
 
-  <p>So we have this monotonic ticking and we have the wall clock
-  time. Two unreliable times that together can give us an estimate of
-  an actual wall clock time that does not jump around and that
-  monotonically moves forward. If the tick counter has a high
-  resolution, this is fairly easy to do, if the counter has a low
-  resolution, it's more expensive, but still doable down to
-  frequencies of 50-60 Hz (of the tick counter).</p>
-
-  <p>So the corrected time is the nearest approximation of an atomic
-  clock that is available on the computer. We want it to have the
-  following properties:</p>
-  <taglist>
-    <tag>Monotonic</tag>
-    <item>The clock should not move backwards</item>
-    <tag>Intervals should be near the truth</tag>
-    <item>We want the actual time (as measured by an atomic clock or
-    an astronomer) that passes between two time stamps, T1 and T2, to be as
-    near to T2 - T1 as possible.</item>
-    <tag>Tight coupling to the wall clock</tag>
-    <item>We want a timer that is to be fired when the wall clock
-    reaches a time in the future, to fire as near to that point in
-    time as possible</item>
-  </taglist>
-  <p>To meet all the criteria, we have to utilize both times in such a
-  way that Erlangs "corrected time" moves slightly slower or slightly
-  faster than the wall clock to get in sync with it. The word
-  "slightly" means a maximum of 1% difference to the wall clock time,
-  meaning that a sudden change in the wall clock of one minute, takes
-  100 minutes to fix, by letting all "corrected time" move 1% slower
-  or faster.</p>
-
-  <p>Needless to say, correcting for a faulty handling of daylight
-  saving time may be disturbing to a user comparing wall clock
-  time to for example calendar:now_to_local_time(erlang:now()). But
-  calendar:now_to_local_time/1 is not supposed to be used for presenting wall
-  clock time to the user.</p>
-
-  <p>Time correction is not perfect, but it saves you from the havoc
-  of clocks jumping around, which would make timers in your program
-  fire far to late or far to early and could bring your whole system
-  to it's knees (or worse) just because someone detected a small error
-  in the wall clock time of the server where your program runs. So
-  while it might be confusing, it is still a really good feature of
-  Erlang and you should not throw it away using time functions which
-  may give you higher benchmark results, not unless you really know
-  what you're doing.</p>
+  </section>
 
+  <marker id="Time_Correction"/>
   <section>
-    <title>What does time correction mean in my system?</title>
-    <p>Time correction means that Erlang estimates a time from current
-    and previous settings of the wall clock, and it uses a fairly
-    exact tick counter to detect when the wall clock time has jumped
-    for some reason, slowly adjusting to the new value.</p>
-
-    <p>In practice, this means that the difference between two calls
-    to time corrected functions, like erlang:now(), might differ up to
-    one percent from the corresponding calls to non time corrected
-    functions (like os:timestamp()). Furthermore, if comparing
-    calendar:local_time/0 to calendar:now_to_local_time(erlang:now()),
-    you might temporarily see a difference, depending on how well kept your
-    system is.</p>
-
-    <p>It is important to understand that it is (to the program)
-    always unknown if it is the wall clock time that moves in the
-    wrong pace or the Erlang corrected time. The only way to determine
-    that, is to have an external source of universally correct time. If
-    some such source is available, the wall clock time can be kept
-    nearly perfect at all times, and no significant difference will be
-    detected between erlang:now/0's pace and the wall clock's.</p>
-
-    <p>Still, the time correction will mean that your system keeps
-    it's real time characteristics very well, even when the wall clock
-    is unreliable.</p>
+    <title>Time Correction</title>
+    <p>If time correction is enabled, the Erlang runtime system
+    will make use of both
+    <seealso marker="#OS_System_Time">OS system time</seealso>
+    and <seealso marker="#OS_Monotonic_Time">OS monotonic time</seealso>,
+    in order to make adjustments of the frequency of the Erlang
+    monotonic clock. Time correction will ensure that
+    <seealso marker="#Erlang_Monotonic_Time">Erlang monotonic time</seealso>
+    will not warp, and that the frequency is relatively accurate.
+    The type of adjustments made to the frequency depends on the
+    time warp mode used. This will be discussed in more details in
+    the <seealso marker="#Time_Warp_Modes">time warp modes</seealso>
+    section below.</p>
+
+    <p>By default time correction will be enabled if support for
+    it on the specific platform exist. Support for it includes
+    both an OS monotonic time provided by the OS, and an
+    implementation in the Erlang runtime system utilizing the
+    OS monotonic time. You can check if your system has support
+    for OS monotonic time by calling
+    <seealso marker="erlang#system_info_os_monotonic_time_source"><c>erlang:system_info(os_monotonic_time_source)</c></seealso>,
+    and you can check if time correction is enabled on your
+    system by calling
+    <seealso marker="erlang#system_info_time_correction"><c>erlang:system_info(time_correction)</c></seealso>.</p>
+
+    <p>Time correction is enabled or disabled by passing the
+    <seealso marker="erl#+c"><c>+c [true|false]</c></seealso>
+    command line argument to <c>erl</c>.</p>
+
+    <p>If time correction is disabled, Erlang monotonic time
+    may warp forwards, it may stop and even freeze for extended
+    periods of time, and there are no guarantees that the frequency
+    of the Erlang monotonic clock is accurate or stable.</p>
+
+    <p><em>You typically never want to disable time correction</em>.
+    Previously there was a performance penalty associated with time
+    correction, but nowadays it is most often the other way around.
+    By disabling time correction you are likely to get bad scalability,
+    bad performance, and bad time measurements.</p>
   </section>
+
+
+  <marker id="Time_Warp_Safe_Code"/>
   <section>
-    <title>Where does Erlang use corrected time?</title>
-    <p>For all functionality where real time characteristics are
-    desirable, time correction is used. This basically means:</p>
-    <taglist>
-      <tag>erlang:now/0</tag>
-      <item>The infamous erlang:now/0 function uses time correction so
-      that differences between two "now-timestamps" will correspond to
-      other timeouts in the system. erlang:now/0 also holds other
-      properties, discussed later.</item>
-      <tag>receive ... after</tag>
-      <item>Timeouts on receive uses time correction to determine a
-      stable timeout interval.</item>
-      <tag>The timer module</tag>
-      <item>As the timer module uses other built in functions which
-      deliver corrected time, the timer module itself works with
-      corrected time.</item>
-      <tag>erlang:start_timer/3 and erlang:send_after/3</tag>
-      <item>The timer BIF's work with corrected time, so that they
-      will not fire prematurely or too late due to changes in the wall
-      clock time.</item>
-    </taglist>
-
-    <p>All other functionality in the system where erlang:now/0 or any
-    other time corrected functionality is used, will of course
-    automatically benefit from it, as long as it's not "optimized" to
-    use some other time stamp function (like os:timestamp/0).</p>
-
-    <p>Modules like calendar and functions like erlang:localtime/0 use
-    the wall clock time as it is currently set on the system. They
-    will not use corrected time. However, if you use a now-value and
-    convert it to local time, you will get a corrected local time
-    value, which may or may not be what you want. Typically older code
-    tend to use erlang:now/0 as a wall clock time, which is usually
-    correct (at least when testing), but might surprise you when
-    compared to other times in the system.</p>
+    <title>Time Warp Safe Code</title>
+    <p>Time warp safe code is code that is able to handle
+    a time warp of
+    <seealso marker="#Erlang_System_Time">Erlang system time</seealso>.
+    </p>
+
+    <p><seealso marker="erlang#now/0"><c>erlang:now/0</c></seealso>
+    behaves very bad when Erlang system time warps. When Erlang
+    system time do a time warp backwards, the values returned
+    from <c>erlang:now/0</c> will freeze (if you disregard the
+    micro second increments made due to the actual call) until
+    OS system time reach the point of the last value returned by
+    <c>erlang:now/0</c>. This freeze might continue for very
+    long periods of time. It might take years, decades,
+    and even longer than this until the freeze stops.</p>
+
+    <p>All uses of <c>erlang:now/0</c> are not necessarily
+    time warp unsafe. If you do not use it to get time, it
+    will be time warp safe. However <em>all uses of
+    <c>erlang:now/0</c> are suboptimal</em> from a performance
+    and scalability perspective. So you really want to replace
+    the usage of it with other functionality. For examples
+    of how to replace the usage of <c>erlang:now/0</c>,
+    see the <seealso marker="#Dos_and_Donts">Dos and Donts</seealso>
+    section.</p>
   </section>
+
+  <marker id="Time_Warp_Modes"/>
   <section>
-    <title>What is erlang:now/0 really?</title>
-    <p>erlang:now/0 is a function designed to serve multiple purposes
-    (or a multi-headed beast if you're a VM designer). It is expected
-    to hold the following properties:</p>
-    <taglist>
-      <tag>Monotonic</tag>
-      <item>erlang:now() never jumps backwards - it always moves
-      forward</item>
-      <tag>Interval correct</tag>
-      <item>The interval between two erlang:now() calls is expected to
-      correspond to the correct time in real life (as defined by an
-      atomic clock, or better)</item>
-      <tag>Absolute correctness</tag>
-      <item>The erlang:now/0 value should be possible to convert to an
-      absolute and correct date-time, corresponding to the real world
-      date and time (the wall clock)</item>
-      <tag>System correspondence</tag>
-      <item>The erlang:now/0 value converted to a date-time is
-      expected to correspond to times given by other programs on the
-      system (or by functions like os:timestamp/0)</item>
-      <tag>Unique</tag>
-      <item>No two calls to erlang:now on one Erlang node should
-      return the same value</item>
-    </taglist>
-    <p>All these requirements are possible to uphold at the same
-    time if (and only if):</p>
-    <taglist>
-      <tag>The wall clock time of the system is perfect</tag>
-      <item>The system (Operating System) time needs to be perfectly
-      in sync with the actual time as defined by an atomic clock or
-      a better time source. A good installation using NTP, and that is
-      up to date before Erlang starts, will have properties that for
-      most users and programs will be near indistinguishable from the
-      perfect time. Note that any larger corrections to the time done
-      by hand, or after Erlang has started, will partly (or
-      temporarily) invalidate some of the properties, as the time is
-      no longer perfect.</item>
-      <tag>Less than one call per microsecond to erlang:now/0 is
-      done</tag>
-      <item>This means that at <em>any</em> microsecond interval in
-      time, there can be no more than one call to erlang:now/0 in the
-      system. However, for the system not to loose it's properties
-      completely, it's enough that it on average is no more than one
-      call per microsecond (in one Erlang node).</item>
-    </taglist>
-    <p>The uniqueness property of erlang:now/0 is the most limiting
-    property. It means that erlang:now() maintains a global state and
-    that there is a hard-to-check property of the system that needs to
-    be maintained. For most applications this is still not a problem,
-    but a future system might very well manage to violate the
-    frequency limit on the calls globally. The uniqueness property is
-    also quite useless, as there are globally unique references that
-    provide a much better unique value to programs. However the
-    property will need to be maintained unless a really subtle
-    backward compatibility issue is to be introduced.</p>
+    <title>Time Warp Modes</title>
+
+    <p>Current <seealso marker="#Erlang_System_Time">Erlang system
+    time</seealso> is determined by adding current
+    <seealso marker="erlang#monotonic_time/0">Erlang monotonic time</seealso>
+    with current
+    <seealso marker="erlang#time_offset/0">time offset</seealso>. The
+    time offset is managed differently depending on which time
+    warp mode you use. The time warp mode is set by passing the
+    <seealso marker="erl#+C_"><c>+C
+    [no_time_warp|single_time_warp|multi_time_warp]</c></seealso>
+    command line argument to <c>erl</c>.</p>
+
+    <marker id="No_Time_Warp_Mode"/>
+    <section>
+      <title>No Time Warp Mode</title>
+      <p>The time offset is determined at runtime system start
+      and will after this not change. This is the default behavior.
+      Not because it is the best mode (which it isn't). It is
+      default only because this is how the runtime system always
+      has behaved until ERTS version 7.0, and you have to ensure
+      that your Erlang code that may execute during a time warp is
+      <seealso marker="#Time_Warp_Safe_Code">time warp safe</seealso>
+      before you can enable other modes.</p>
+
+      <p>Since the time offset is not allowed to change, time
+      correction needs to adjust the frequency of the Erlang
+      monotonic clock in order to smoothly align Erlang system
+      time with OS system time. A big downside of this approach
+      is that we on purpose will use a faulty frequency on the
+      Erlang monotonic clock if adjustments are needed. This
+      error may be as big as 1%. This error will show up in all
+      time measurements in the runtime system.</p>
+
+      <p>If time correction is not enabled, the Erlang monotonic
+      time will freeze when the OS system time leap backwards.
+      The freeze of the monotonic time will continue until
+      OS system time catch up. The freeze may continue for
+      a very long time. When OS system time leaps forwards,
+      Erlang monotonic time will also leap forward.</p>
+    </section>
+
+    <marker id="Single_Time_Warp_Mode"/>
+    <section>
+      <title>Single Time Warp Mode</title>
+      <p>This mode is more or less a backwards compatibility mode
+      as of its introduction.</p>
+      <p>On an embedded system it is not uncommon that the system
+      has no power supply at all, not even a battery, when it is
+      shut off. The system clock on such a system will typically
+      be way off when the system boots. If the
+      <seealso marker="#No_Time_Warp_Mode">no time warp mode</seealso>
+      is used, and the Erlang runtime system is started before
+      the OS system time has been corrected, the Erlang system
+      time may be wrong for a very long time, even centuries or
+      more.</p>
+      <p>If you for some reason need to use Erlang code that
+      is not
+      <seealso marker="#Time_Warp_Safe_Code">time warp safe</seealso>,
+      and you need to start the Erlang runtime system before the OS
+      system time has been corrected, you may want to use the single
+      time warp mode. Note that there are limitations to when you can
+      execute time warp unsafe code using this mode. If it is possible
+      to only utilize time warp safe code, it is much better to use
+      the <seealso marker="#Multi_Time_Warp_Mode">multi time warp
+      mode</seealso> instead.
+      </p>
+
+      <p>Using the single time warp mode, the time offset is
+      handled in two phases:</p>
+
+      <taglist>
+	<tag>Preliminary Phase</tag>
+	<item>
+	  <p>The preliminary phase starts when the runtime
+	  system starts. A preliminary time offset based on
+	  current OS system time is determined. This offset will
+	  from now on be fixed during the whole preliminary phase.</p>
+
+	  <p>If time correction is enabled, the Erlang
+	  monotonic clock will only use the OS monotonic time as
+	  time source during this phase. That is, during the
+	  preliminary phase changes in OS system time will have
+	  no effect on Erlang system time and/or Erlang
+	  monotonic time what so ever.</p>
+
+	  <p>If time correction is disabled, changes in OS system
+	  time will effect the monotonic clock the same way as
+	  when the <seealso marker="#No_Time_Warp_Mode">no time warp
+	  mode</seealso> is used.</p>
+	</item>
+
+	<tag>Final Phase</tag>
+	<item>
+
+	  <p>The final phase begin when the user finalize the time
+	  offset by calling
+	  <seealso marker="erlang#system_flag_time_offset"><c>erlang:system_flag(time_offset, finalize)</c></seealso>.
+	  The finalization can only be performed once.
+	  </p>
+
+	  <p>During finalization, the time offset is adjusted and
+	  fixated so that current Erlang system time align with
+	  current OS system time. Since the time offset
+	  may be changed, the Erlang system time may do
+	  a time warp at this point. The time offset will from
+	  now on be fixed until the runtime system terminates.
+	  If time correction has been enabled, the time correction
+	  also begins when this phase begins. When the system is
+	  in the final phase it behaves exactly as in the
+	  <seealso marker="#No_Time_Warp_Mode">no time warp
+	  mode</seealso>.</p>
+
+	</item>
+      </taglist>
+
+      <p>In order for this to work properly there are two
+      requirements that the user needs to ensure are
+      satisfied:</p>
+
+      <taglist>
+	<tag>Forward Time Warp</tag>
+	<item><p>The time warp made when finalizing the time offset
+	can only be done forwards without encountering problems.
+	This implies that the user has to ensure that the OS
+	system time is set to a time earlier or equal to actual
+	POSIX time before starting the Erlang runtime system. If
+	you are not completely sure the OS system time is correct,
+	set it to a time that is guaranteed to be earlier than
+	actual POSIX time before starting the Erlang runtime
+	system just to be safe.</p></item>
+
+	<tag>Finalize Correct OS System Time</tag>
+	<item><p>The OS system time needs to be correct when the
+	the user finalizes the time offset.</p></item>
+      </taglist>
+
+      <p>If these requirements are not fulfilled, the system
+      may behave very bad.
+      </p>
+
+      <p>Assuming that the requirements above are fulfilled,
+      time correction is enabled, and that the OS system time
+      is adjusted using some time adjustment protocol like NTP
+      or similar, only small adjustments of the Erlang monotonic
+      time should be needed in order to keep system times
+      aligned after finilization. As long as the system is not
+      suspended, the largest adjustments needed should be for
+      inserted (or deleted) leap seconds.</p>
+
+      <warning><p>In order to be able to use this mode you have
+      to ensure that all Erlang code that will execute in
+      both phases are
+      <seealso marker="#Time_Warp_Safe_Code">time warp
+      safe</seealso>.</p>
+      <p>Code that only execute in the final phase does not have
+      to be able to cope with the time warp.</p></warning>
+
+    </section>
+
+    <marker id="Multi_Time_Warp_Mode"/>
+    <section>
+      <title>Multi Time Warp Mode</title>
+
+      <p><em>Multi time warp mode in combination with time
+      correction is the preferred configuration</em>. This since,
+      on almost all platforms, the Erlang runtime system will have
+      better performance, will scale better, will behave better,
+      and since the accuracy, and precision of time measurements
+      will be better. Only Erlang runtime systems executing on
+      ancient platforms will benefit from another configuration.</p>
+
+      <p>The time offset may change at any time without limitations.
+      That is, Erlang system time may perform time warps both
+      forwards and backwards at <em>any</em> time. Since we align
+      the Erlang system time with the OS system time by changing
+      the time offset, we can enable a time correction that tries
+      to adjust the frequency of the Erlang monotonic clock to be as
+      correct as possible. This will make time measurements using
+      the Erlang monotonic time more accurate and precise.</p>
+
+      <p>If time correction is disabled, Erlang monotonic time
+      will leap forward if OS system time leaps forward. If the
+      OS system time leaps backwards, Erlang monotonic time will
+      stop briefly but it does not freeze for extended periods
+      of time. This since the time offset is changed in order to
+      align Erlang system time with OS system time.</p>
+
+      <warning><p>In order to be able to use this mode you have
+      to ensure that all Erlang code that will execute on the
+      runtime system is
+      <seealso marker="#Time_Warp_Safe_Code">time warp
+      safe</seealso>.</p></warning>
+    </section>
   </section>
+
+  <marker id="The_New_Time_API"/>
   <section>
-    <title>Should I use erlang:now/0 or os:timestamp/0</title>
-    <p>The simple answer is to use erlang:now/0 for everything where
-    you want to keep real time characteristics, but use os:timestamp
-    for things like logs, user communication and debugging (typically
-    timer:ts uses os:timestamp, as it is a test tool, not a real world
-    application API). The benefit of using os:timestamp/0 is that it's
-    faster and does not involve any global state (unless the operating
-    system has one). The downside is that it will be vulnerable to wall
-    clock time changes.</p>
+    <title>The New Time API</title>
+
+    <p>The old time API is based on
+    <seealso marker="erlang#now/0"><c>erlang:now/0</c></seealso>.
+    The major issue with <c>erlang:now/0</c> is that it was
+    intended to be used for so many unrelated things. This
+    tied these unrelated operations together and unnecessarily
+    caused performance, scalability as well as accuracy, and
+    precision issues for operations that do not need to have
+    such issues. The new API spreads different functionality
+    over multiple functions in order to improve on this.</p>
+
+    <p>In order to be backwards compatible <c>erlang:now/0</c> will
+    remain as is, but <em>you are strongly discouraged from using
+    it</em>. A lot of uses of <c>erlang:now/0</c> will also
+    prevent you from using the new
+    <seealso marker="#Multi_Time_Warp_Mode">multi time warp
+    mode</seealso> which is an important part of this
+    new time functionality improvement.</p>
+
+    <p>Some of the new BIFs on some systems, perhaps surprisingly,
+    return negative integer values on a newly started run time
+    system. This is not a bug, but a memory usage optimization.</p>
+
+    <p>The new API consists of a number of new BIFs:</p>
+    <list>
+      <item><p><seealso marker="erlang#convert_time_unit/3"><c>erlang:convert_time_unit/3</c></seealso></p></item>
+      <item><p><seealso marker="erlang#monotonic_time/0"><c>erlang:monotonic_time/0</c></seealso></p></item>
+      <item><p><seealso marker="erlang#monotonic_time/1"><c>erlang:monotonic_time/1</c></seealso></p></item>
+      <item><p><seealso marker="erlang#system_time/0"><c>erlang:system_time/0</c></seealso></p></item>
+      <item><p><seealso marker="erlang#system_time/1"><c>erlang:system_time/1</c></seealso></p></item>
+      <item><p><seealso marker="erlang#time_offset/0"><c>erlang:time_offset/0</c></seealso></p></item>
+      <item><p><seealso marker="erlang#time_offset/1"><c>erlang:time_offset/1</c></seealso></p></item>
+      <item><p><seealso marker="erlang#timestamp/0"><c>erlang:timestamp/0</c></seealso></p></item>
+      <item><p><seealso marker="erlang#unique_integer/0"><c>erlang:unique_integer/0</c></seealso></p></item>
+      <item><p><seealso marker="erlang#unique_integer/1"><c>erlang:unique_integer/1</c></seealso></p></item>
+      <item><p><seealso marker="kernel:os#system_time/0"><c>os:system_time/0</c></seealso></p></item>
+      <item><p><seealso marker="kernel:os#system_time/1"><c>os:system_time/1</c></seealso></p></item>
+    </list>
+    <p>and a number of extensions of existing BIFs:</p>
+    <list>
+      <item><p><seealso marker="erlang#monitor/2"><c>erlang:monitor(time_offset, clock_service)</c></seealso></p></item>
+      <item><p><seealso marker="erlang#system_flag_time_offset"><c>erlang:system_flag(time_offset, finalize)</c></seealso></p></item>
+      <item><p><seealso marker="erlang#system_info_os_monotonic_time_source"><c>erlang:system_info(os_monotonic_time_source)</c></seealso></p></item>
+      <item><p><seealso marker="erlang#system_info_time_offset"><c>erlang:system_info(time_offset)</c></seealso></p></item>
+      <item><p><seealso marker="erlang#system_info_time_warp_mode"><c>erlang:system_info(time_warp_mode)</c></seealso></p></item>
+      <item><p><seealso marker="erlang#system_info_time_correction"><c>erlang:system_info(time_correction)</c></seealso></p></item>
+      <item><p><seealso marker="erlang#system_info_start_time"><c>erlang:system_info(start_time)</c></seealso></p></item>
+    </list>
+
+    <marker id="The_New_Erlang_Monotonic_Time"/>
+    <section>
+      <title>The New Erlang Monotonic Time</title>
+      <p>The Erlang monotonic time as such is new as of ERTS
+      version 7.0. It has been introduced in order to be able
+      to detach time measurements such as elapsed time from
+      calender time. It is very common that one is interested
+      in measuring elapsed time or specifying a time relative
+      to another point in time without having any need to know
+      what the involved times are in UTC or any other
+      globally defined time scale. By introducing a time scale
+      that has a local definition of where it starts, it is
+      possible to manage time that do not concern calender
+      time on that time scale. Erlang monotonic time use
+      such a time scale with a locally defined start.</p>
+
+      <p>The introduction of Erlang monotonic time gives us
+      the possibility to adjust the two Erlang times (Erlang
+      monotonic time and Erlang system time) separately. By
+      doing this, accuracy of elapsed time does not have to
+      suffer just because the system time happened to be
+      wrong at some point in time. Separate adjustments
+      of the two times are only performed in the time warp
+      modes, and only fully separated in the
+      <seealso marker="#Multi_Time_Warp_Mode">multi
+      time warp mode</seealso>. All other modes than the
+      multi time warp mode are there for backwards
+      compatibility reasons, and when using these the
+      accuracy of Erlang monotonic time suffer since
+      the adjustments of Erlang monotonic time in these
+      modes are more or less tied to the Erlang system
+      time.</p>
+
+      <p>The adjustment of system time could have been made
+      smother than using a time warp approach, but we think
+      that would be a bad choice. Since we are able to
+      express and measure time that aren't connected to
+      calender time by the use of Erlang monotonic time, it
+      is better to expose the change in Erlang system time
+      immediately. This since it makes it possible for the
+      Erlang applications executing on the system to react
+      on the change in system time as soon as possible. This
+      is also more or less exactly how most OSes handle this
+      (OS monotonic time and OS system time). By adjusting
+      system time smoothly we would just hide the fact that
+      system time changed and make it harder for the Erlang
+      applications to react to the change in a sensible way.</p>
+
+      <p>In order to be able to react to a change in Erlang
+      system time you have to be able to detect that it
+      happened. The change in Erlang system time occurs when
+      current time offset is changed. We have therefore
+      introduced the possibility to monitor the time offset
+      using
+      <seealso marker="erlang#monitor/2"><c>erlang:monitor(time_offset, clock_service)</c></seealso>. A process monitoring the time
+      offset will be sent a message on the following format
+      when the time offset is changed:</p>
+      <code type="none">{'CHANGE', MonitorReference, time_offset, clock_service, NewTimeOffset}</code>
+    </section>
+
+    <marker id="Unique_Values"/>
+    <section>
+      <title>Unique Values</title>
+      <p>Besides reporting time <c>erlang:now/0</c> also
+      produce unique and strictly monotonically increasing
+      values. In order to detach this functionality from
+      time measurements we have introduced
+      <seealso marker="erlang#unique_integer/1"><c>erlang:unique_integer()</c></seealso>.
+      </p>
+    </section>
+
+    <marker id="Dos_and_Donts"/>
+    <section>
+      <title>Dos and Don'ts</title>
+      <p>Previously <c>erlang:now/0</c> was the only option for doing
+      quite a lot of things. We will look at a few different things
+      <c>erlang:now/0</c> could be used for, and how you want to do
+      this using the new API:</p>
+
+      <marker id="Dos_and_Donts_Retrieve_Erlang_System_Time"/>
+      <section>
+	<title>Retrieve Erlang System Time</title>
+	<dont>
+	  <p>
+	    use <c>erlang:now/0</c> in order to retrieve current Erlang
+	    system time.
+	  </p>
+	</dont>
+	<do>
+	  <p>
+	    use
+	    <seealso marker="erlang#system_time/1"><c>erlang:system_time/1</c></seealso>
+	    in order to retrieve current Erlang system time on the
+	    <seealso marker="erlang#type_time_unit">time unit</seealso>
+	    of your choice.</p>
+	    <p>If you want the same format as returned by <c>erlang:now/0</c>, use
+	    <seealso marker="erlang#timestamp/0"><c>erlang:timestamp/0</c></seealso>.
+	    </p>
+	</do>
+      </section>
+
+      <marker id="Dos_and_Donts_Measure_Elapsed_Time"/>
+      <section>
+	<title>Measure Elapsed Time</title>
+	<dont>
+	  <p>
+	    take timestamps with <c>erlang:now/0</c> and calculate
+	    the difference in time with
+	    <seealso marker="stdlib:timer#now_diff/2"><c>timer:now_diff/2</c></seealso>.
+	  </p>
+	</dont>
+	<do>
+	  <p>
+	    take timestamps with
+	    <seealso marker="erlang#monotonic_time/0"><c>erlang:monotonic_time/0</c></seealso>
+	    and calculate the time difference using ordinary subtraction.
+	    The result will be in <c>native</c>
+	    <seealso marker="erlang#type_time_unit">time unit</seealso>.
+	    If you want to convert the
+	    result to another time unit you can do this using
+	    <seealso marker="erlang#convert_time_unit/3"><c>erlang:convert_time_unit/3</c></seealso>.
+	    </p>
+	    <p>Another easier way of doing this is to use
+	    <seealso marker="erlang#monotonic_time/1"><c>erlang:monotonic_time/1</c></seealso>
+	    with desired time unit. However, you may lose accuracy,
+	    and precision this way.
+	    </p>
+	</do>
+      </section>
+
+      <marker id="Dos_and_Donts_Determine_Order_of_Events"/>
+      <section>
+	<title>Determine Order of Events</title>
+	<dont>
+	  <p>
+	    determine the order of events by saving a timestamp
+	    with <c>erlang:now/0</c> when the event happens.
+	  </p>
+	</dont>
+	<do>
+	  <p>
+	    determine the order of events by saving the integer
+	    returned by
+	    <seealso marker="erlang#unique_integer/1"><c>erlang:unique_integer([monotonic])</c></seealso>
+	    when the event happens. These integers will be strictly
+	    monotonically ordered on current runtime system instance
+	    corresponding to creation time.
+	  </p>
+	</do>
+      </section>
+
+      <marker id="Dos_and_Donts_Determine_Order_of_Events_With_Time_of_the_Event"/>
+      <section>
+	<title>Determine Order of Events With Time of the Event</title>
+	<dont>
+	  <p>
+	    determine the order of events by saving a timestamp
+	    with <c>erlang:now/0</c> when the event happens.
+	  </p>
+	</dont>
+	<do>
+	  <p>
+	    determine the order of events by saving a tuple
+	    containing
+	    <seealso marker="erlang#monotonic_time/0">monotonic time</seealso>
+	    and a <seealso marker="erlang#unique_integer/1">strictly
+	    monotonically increasing integer</seealso> like this:</p>
+	    <code type="none">
+Time = erlang:monotonic_time(),
+UMI = erlang:unique_integer([monotonic]),
+EventTag = {Time, UMI}</code>
+	    <p>These tuples will be strictly monotonically ordered
+	    on the current runtime system instance according to
+	    creation time. Note that it is important that the
+	    monotonic time is in the first element (the most
+	    significant element when comparing 2-tuples). Using
+	    the monotonic time in the tuples, you can calculate time
+	    between events.</p>
+	    <p>If you are interested in the Erlang system time at the
+	    time when the event occurred you can also save the time
+	    offset before or after saving the events using
+	    <seealso marker="erlang#time_offset/0"><c>erlang:time_offset/0</c></seealso>.
+	    Erlang monotonic time added with the time
+	    offset corresponds to Erlang system time.</p>
+	    <p>If you are executing in a mode where time offset
+	    may change and you want to be able to get the actual
+	    Erlang system time when the event occurred you can
+	    save the time offset as a third element in the tuple
+	    (the least significant element when comparing 3-tuples).</p>
+	</do>
+      </section>
+
+      <marker id="Dos_and_Donts_Create_a_Unique_Name"/>
+      <section>
+	<title>Create a Unique Name</title>
+	<dont>
+	  <p>
+	    use the values returned from <c>erlang:now/0</c>
+	    in order to create a name unique on the current
+	    runtime system instance.
+	  </p>
+	</dont>
+	<do>
+	  <p>
+	    use the value returned from
+	    <seealso marker="erlang#unique_integer/0"><c>erlang:unique_integer/0</c></seealso>
+	    in order to create a name unique on the current runtime system
+	    instance. If you only want positive integers, you can use
+	    <seealso marker="erlang#unique_integer/1"><c>erlang:unique_integer([positive])</c></seealso>.
+	  </p>
+	</do>
+      </section>
+
+      <marker id="Dos_and_Donts_Seed_Random_Number_Generation_With_a_Unique_Value"/>
+      <section>
+	<title>Seed Random Number Generation With a Unique Value</title>
+	<dont>
+	  <p>
+	    seed random number generation using <c>erlang:now()</c>.
+	  </p>
+	</dont>
+	<do>
+	  <p>
+	    seed random number generation using a combination of
+	    <seealso marker="erlang#monotonic_time/0"><c>erlang:monotonic_time()</c></seealso>,
+	    <seealso marker="erlang#time_offset/0"><c>erlang:time_offset()</c></seealso>,
+	    <seealso marker="erlang#unique_integer/0"><c>erlang:unique_integer()</c></seealso>, and other functionality.
+	  </p>
+	  </do>
+      </section>
+
+      <p>To sum this section up: <em>Don't use <c>erlang:now/0</c>!</em></p>
+    </section>
   </section>
+
+  <marker id="Supporting_Both_New_and_Old_OTP_Releases"/>
   <section>
-    <title>Turning off time correction</title>
-    <p>If, for some reason, time correction causes trouble and you are
-    absolutely confident that the wall clock on the system is nearly
-    perfect, you can turn off time correction completely by giving the
-    <c>+c</c> option to <c>erl</c>. The probability for this being a
-    good idea, is very low.</p>
+    <title>Supporting Both New and Old OTP Releases</title>
+    <p>Your code may be required to be able to run on a variety 
+    of OTP installations of different OTP releases. If so, you
+    can not just use the new API out of the box, since it will
+    not be available on old pre OTP 18 releases. The solution
+    is <em>not</em> to avoid using the new API, since your
+    code then won't be able to benefit from the scalability
+    and accuracy improvements made. Instead you want to use the
+    new API when available, and fall back on <c>erlang:now/0</c>
+    when it is not available. Fortunately almost all of the new
+    API can easily be implemented using existing primitives
+    (except for
+    <seealso marker="erlang#system_info_start_time"><c>erlang:system_info(start_time)</c></seealso>, and
+    <seealso marker="erlang#system_info_os_monotonic_time_source"><c>erlang:system_info(os_monotonic_time_source)</c></seealso>).
+    By wrapping the API with functions that fall back on
+    <c>erlang:now/0</c> when the new API is not available,
+    and using these wrappers instead of using the API directly
+    the problem is solved. These wrappers can for example
+    be implemented as in
+    <url href="time_compat.erl"><c>$ERL_TOP/erts/example/time_compat.erl</c></url>.</p>
   </section>
 </chapter>
-
diff --git a/erts/emulator/Makefile.in b/erts/emulator/Makefile.in
index 7145824f91..560cab396d 100644
--- a/erts/emulator/Makefile.in
+++ b/erts/emulator/Makefile.in
@@ -764,7 +764,8 @@ RUN_OBJS = \
 	$(OBJDIR)/erl_bif_ddll.o  	$(OBJDIR)/erl_bif_guard.o \
 	$(OBJDIR)/erl_bif_info.o	$(OBJDIR)/erl_bif_op.o \
 	$(OBJDIR)/erl_bif_os.o		$(OBJDIR)/erl_bif_lists.o \
-	$(OBJDIR)/erl_bif_trace.o	$(OBJDIR)/erl_bif_wrap.o \
+	$(OBJDIR)/erl_bif_trace.o	$(OBJDIR)/erl_bif_unique.o \
+	$(OBJDIR)/erl_bif_wrap.o \
 	$(OBJDIR)/erl_trace.o		$(OBJDIR)/copy.o \
 	$(OBJDIR)/utils.o		$(OBJDIR)/bif.o \
 	$(OBJDIR)/io.o 			$(OBJDIR)/erl_printf_term.o\
diff --git a/erts/emulator/beam/atom.names b/erts/emulator/beam/atom.names
index 5d06a32941..ced35be265 100644
--- a/erts/emulator/beam/atom.names
+++ b/erts/emulator/beam/atom.names
@@ -144,9 +144,11 @@ atom catchlevel
 atom cd
 atom cdr
 atom cflags
+atom CHANGE='CHANGE'
 atom characters_to_binary_int
 atom characters_to_list_int
 atom clear
+atom clock_service
 atom close
 atom closed
 atom code
@@ -156,6 +158,7 @@ atom compat_rel
 atom compile
 atom compressed
 atom config_h
+atom convert_time_unit
 atom connect
 atom connected
 atom connection_closed
@@ -236,7 +239,7 @@ atom first
 atom firstline
 atom flags
 atom flush
-atom flush_monitor_message
+atom flush_monitor_messages
 atom force
 atom format_cpu_topology
 atom free
@@ -344,6 +347,8 @@ atom message_queue_len
 atom messages
 atom meta
 atom meta_match_spec
+atom micro_seconds
+atom milli_seconds
 atom min_heap_size
 atom min_bin_vheap_size
 atom minor_version
@@ -354,12 +359,15 @@ atom monitored_by
 atom monitor
 atom monitor_nodes
 atom monitors
+atom monotonic
 atom more
 atom multi_scheduling
 atom multiline
+atom nano_seconds
 atom name
 atom named_table
 atom namelist
+atom native
 atom native_addresses
 atom Neq='=/='
 atom Neqeq='/='
@@ -450,6 +458,7 @@ atom ports
 atom port_count
 atom port_limit
 atom port_op
+atom positive
 atom print
 atom priority
 atom private
@@ -509,6 +518,7 @@ atom schedulers_online
 atom scheme
 atom scientific
 atom scope
+atom seconds
 atom sensitive
 atom sequential_tracer
 atom sequential_trace_token
@@ -554,6 +564,7 @@ atom term_to_binary_trap
 atom this
 atom thread_pool_size
 atom threads
+atom time_offset
 atom timeout
 atom timeout_value
 atom Times='*'
diff --git a/erts/emulator/beam/benchmark.h b/erts/emulator/beam/benchmark.h
index 766edaac42..7f267b7201 100644
--- a/erts/emulator/beam/benchmark.h
+++ b/erts/emulator/beam/benchmark.h
@@ -175,10 +175,10 @@ extern BM_TIMER_T start_time;
 
 #else /* !USE_PERFCTR  (Assuming Solaris) */
 
-#define BM_TIMER_T hrtime_t
-#define BM_START_TIMER(t) system_clock = sys_gethrtime()
+#define BM_TIMER_T ErtsMonotonicTime
+#define BM_START_TIMER(t) system_clock = ERTS_MONOTONIC_TO_NSEC(erts_os_monotonic_time())
 #define BM_STOP_TIMER(t) do {                                        \
-    BM_TIMER_T tmp = (sys_gethrtime() - system_clock) - timer_time;  \
+    BM_TIMER_T tmp = (ERTS_MONOTONIC_TO_NSEC(erts_os_monotonic_time()) - system_clock) - timer_time;  \
     t##_time += (tmp > 0 ? tmp : 0);                                 \
 } while(0)
 
diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
index 42dd160e38..ec5122292e 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -40,16 +40,21 @@
 #define ERTS_PTAB_WANT_BIF_IMPL__
 #include "erl_ptab.h"
 #include "erl_bits.h"
+#include "erl_bif_unique.h"
 
-static Export* flush_monitor_message_trap = NULL;
+static Export* flush_monitor_messages_trap = NULL;
 static Export* set_cpu_topology_trap = NULL;
 static Export* await_proc_exit_trap = NULL;
 static Export* await_port_send_result_trap = NULL;
 Export* erts_format_cpu_topology_trap = NULL;
+Export *erts_convert_time_unit_trap = NULL;
 
 static Export *await_sched_wall_time_mod_trap;
 static erts_smp_atomic32_t sched_wall_time;
 
+static erts_smp_mtx_t ports_snapshot_mtx;
+erts_smp_atomic_t erts_dead_ports_ptr; /* To store dying ports during snapshot */
+
 #define DECL_AM(S) Eterm AM_ ## S = am_atom_put(#S, sizeof(#S) - 1)
 
 /*
@@ -391,7 +396,7 @@ remote_demonitor(Process *c_p, DistEntry *dep, Eterm ref, Eterm to)
     return res;
 }
 
-static int demonitor(Process *c_p, Eterm ref)
+static int demonitor(Process *c_p, Eterm ref, Eterm *multip)
 {
    ErtsMonitor *mon = NULL;  /* The monitor entry to delete */
    Process  *rp;    /* Local target process */
@@ -415,65 +420,73 @@ static int demonitor(Process *c_p, Eterm ref)
        goto done;
    }
 
-   if (mon->type != MON_ORIGIN) {
-       res = ERTS_DEMONITOR_BADARG;
-       goto done;
-   }
-   to = mon->pid;
-
-   if (is_atom(to)) {
-       /* Monitoring a name at node to */
-       ASSERT(is_node_name_atom(to));
-       dep = erts_sysname_to_connected_dist_entry(to);
-       ASSERT(dep != erts_this_dist_entry);
-       if (dep)
-	   deref_de = 1;
-   } else {
-       ASSERT(is_pid(to));
-       dep = pid_dist_entry(to);
-   }
-   if (dep != erts_this_dist_entry) {
-       res = remote_demonitor(c_p, dep, ref, to);
-       /* remote_demonitor() unlocks link lock on c_p */
-       unlock_link = 0;
-   }
-   else { /* Local monitor */
-       if (deref_de) {
-	   deref_de = 0;
-	   erts_deref_dist_entry(dep);
+   switch (mon->type) {
+   case MON_TIME_OFFSET:
+       *multip = am_true;
+       erts_demonitor_time_offset(ref);
+       res = ERTS_DEMONITOR_TRUE;
+       break;
+   case MON_ORIGIN:
+       to = mon->pid;
+       *multip = am_false;
+       if (is_atom(to)) {
+	   /* Monitoring a name at node to */
+	   ASSERT(is_node_name_atom(to));
+	   dep = erts_sysname_to_connected_dist_entry(to);
+	   ASSERT(dep != erts_this_dist_entry);
+	   if (dep)
+	       deref_de = 1;
+       } else {
+	   ASSERT(is_pid(to));
+	   dep = pid_dist_entry(to);
        }
-       dep = NULL;
-       rp = erts_pid2proc_opt(c_p,
-			      ERTS_PROC_LOCK_MAIN|ERTS_PROC_LOCK_LINK,
-			      to,
-			      ERTS_PROC_LOCK_LINK,
-			      ERTS_P2P_FLG_ALLOW_OTHER_X);
-       mon = erts_remove_monitor(&ERTS_P_MONITORS(c_p), ref);
+       if (dep != erts_this_dist_entry) {
+	   res = remote_demonitor(c_p, dep, ref, to);
+	   /* remote_demonitor() unlocks link lock on c_p */
+	   unlock_link = 0;
+       }
+       else { /* Local monitor */
+	   if (deref_de) {
+	       deref_de = 0;
+	       erts_deref_dist_entry(dep);
+	   }
+	   dep = NULL;
+	   rp = erts_pid2proc_opt(c_p,
+				  ERTS_PROC_LOCK_MAIN|ERTS_PROC_LOCK_LINK,
+				  to,
+				  ERTS_PROC_LOCK_LINK,
+				  ERTS_P2P_FLG_ALLOW_OTHER_X);
+	   mon = erts_remove_monitor(&ERTS_P_MONITORS(c_p), ref);
 #ifndef ERTS_SMP
-       ASSERT(mon);
+	   ASSERT(mon);
 #else
-       if (!mon)
-	   res = ERTS_DEMONITOR_FALSE;
-       else
+	   if (!mon)
+	       res = ERTS_DEMONITOR_FALSE;
+	   else
 #endif
-       {
-	   res = ERTS_DEMONITOR_TRUE;
-	   erts_destroy_monitor(mon);
-       }
-       if (rp) {
-	   ErtsMonitor *rmon;
-	   rmon = erts_remove_monitor(&ERTS_P_MONITORS(rp), ref);
-	   if (rp != c_p)
-	       erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);
-	   if (rmon != NULL)
-	       erts_destroy_monitor(rmon);
-       }
-       else {
-	   ERTS_SMP_ASSERT_IS_NOT_EXITING(c_p);
-       }
+	   {
+	       res = ERTS_DEMONITOR_TRUE;
+	       erts_destroy_monitor(mon);
+	   }
+	   if (rp) {
+	       ErtsMonitor *rmon;
+	       rmon = erts_remove_monitor(&ERTS_P_MONITORS(rp), ref);
+	       if (rp != c_p)
+		   erts_smp_proc_unlock(rp, ERTS_PROC_LOCK_LINK);
+	       if (rmon != NULL)
+		   erts_destroy_monitor(rmon);
+	   }
+	   else {
+	       ERTS_SMP_ASSERT_IS_NOT_EXITING(c_p);
+	   }
 
+       }
+       break;
+   default:
+       res = ERTS_DEMONITOR_BADARG;
+       *multip = am_false;
+       break;
    }
-
  done:
 
    if (unlock_link)
@@ -490,7 +503,8 @@ static int demonitor(Process *c_p, Eterm ref)
 
 BIF_RETTYPE demonitor_1(BIF_ALIST_1)
 {
-    switch (demonitor(BIF_P, BIF_ARG_1)) {
+    Eterm multi;
+    switch (demonitor(BIF_P, BIF_ARG_1, &multi)) {
     case ERTS_DEMONITOR_FALSE:
     case ERTS_DEMONITOR_TRUE:
 	BIF_RET(am_true);
@@ -508,6 +522,7 @@ BIF_RETTYPE demonitor_1(BIF_ALIST_1)
 BIF_RETTYPE demonitor_2(BIF_ALIST_2)
 {
     Eterm res = am_true;
+    Eterm multi = am_false;
     int info = 0;
     int flush = 0;
     Eterm list = BIF_ARG_2;
@@ -530,13 +545,18 @@ BIF_RETTYPE demonitor_2(BIF_ALIST_2)
     if (is_not_nil(list))
 	goto badarg;
 
-    switch (demonitor(BIF_P, BIF_ARG_1)) {
+    switch (demonitor(BIF_P, BIF_ARG_1, &multi)) {
     case ERTS_DEMONITOR_FALSE:
 	if (info)
 	    res = am_false;
-	if (flush)
-	    BIF_TRAP2(flush_monitor_message_trap, BIF_P, BIF_ARG_1, res);
+	if (flush) {
+	flush_messages:
+	    BIF_TRAP3(flush_monitor_messages_trap, BIF_P,
+		      BIF_ARG_1, multi, res);
+	}
     case ERTS_DEMONITOR_TRUE:
+	if (multi == am_true && flush)
+	    goto flush_messages;
 	BIF_RET(res);
     case ERTS_DEMONITOR_YIELD_TRUE:
 	ERTS_BIF_YIELD_RETURN(BIF_P, am_true);
@@ -744,7 +764,22 @@ BIF_RETTYPE monitor_2(BIF_ALIST_2)
     int deref_de = 0;
 
     /* Only process monitors are implemented */
-    if (BIF_ARG_1 != am_process) {
+    switch (BIF_ARG_1) {
+    case am_time_offset: {
+	Eterm ref;
+	if (BIF_ARG_2 != am_clock_service)
+	    goto error;
+	ref = erts_make_ref(BIF_P);
+	erts_smp_proc_lock(BIF_P, ERTS_PROC_LOCK_LINK);
+	erts_add_monitor(&ERTS_P_MONITORS(BIF_P), MON_TIME_OFFSET,
+			 ref, am_clock_service, NIL);
+	erts_smp_proc_unlock(BIF_P, ERTS_PROC_LOCK_LINK);
+	erts_monitor_time_offset(BIF_P->common.id, ref);
+	BIF_RET(ref);
+    }
+    case am_process:
+	break;
+    default:
 	goto error;
     }
 
@@ -3446,91 +3481,6 @@ BIF_RETTYPE self_0(BIF_ALIST_0)
 
 /**********************************************************************/
 
-/*
-   New representation of refs in R9, see erl_term.h
-
-   In the first data word, only the usual 18 bits are used. Ordinarily,
-   in "long refs" all words are used (in other words, practically never
-   wrap around), but for compatibility with older nodes, "short refs"
-   exist. Short refs come into being by being converted from the old
-   external format for refs (tag REFERENCE_EXT). Short refs are
-   converted back to the old external format.
-
-   When converting a long ref to the external format in the case of
-   preparing for sending to an older node, the ref is truncated by only
-   using the first word (with 18 significant bits), and using the old tag
-   REFERENCE_EXT.
-
-   When comparing refs or different size, only the parts up to the length
-   of the shorter operand are used. This has the desirable effect that a
-   long ref sent to an old node and back will be treated as equal to
-   the original, although some of the bits have been lost.
-
-   The hash value for a ref always considers only the first word, since
-   in the above scenario, the original and the copy should have the same
-   hash value.
-*/
-
-static Uint32 reference0; /* Initialized in erts_init_bif */
-static Uint32 reference1;
-static Uint32 reference2;
-static erts_smp_spinlock_t make_ref_lock;
-static erts_smp_mtx_t ports_snapshot_mtx;
-erts_smp_atomic_t erts_dead_ports_ptr; /* To store dying ports during snapshot */
-
-void
-erts_make_ref_in_array(Uint32 ref[ERTS_MAX_REF_NUMBERS])
-{
-    erts_smp_spin_lock(&make_ref_lock);
-
-    reference0++;
-    if (reference0 >= MAX_REFERENCE) {
-	reference0 = 0;
-	reference1++;
-	if (reference1 == 0) {
-	    reference2++;
-	}
-    }
-
-    ref[0] = reference0;
-    ref[1] = reference1;
-    ref[2] = reference2;
-
-    erts_smp_spin_unlock(&make_ref_lock);
-}
-
-Eterm erts_make_ref_in_buffer(Eterm buffer[REF_THING_SIZE])
-{
-    Eterm* hp = buffer;
-    Uint32 ref[ERTS_MAX_REF_NUMBERS];
-
-    erts_make_ref_in_array(ref);
-    write_ref_thing(hp, ref[0], ref[1], ref[2]);
-    return make_internal_ref(hp);
-}
-
-Eterm erts_make_ref(Process *p)
-{
-    Eterm* hp;
-    Uint32 ref[ERTS_MAX_REF_NUMBERS];
-
-    ERTS_SMP_LC_ASSERT(ERTS_PROC_LOCK_MAIN & erts_proc_lc_my_proc_locks(p));
-
-    hp = HAlloc(p, REF_THING_SIZE);
-
-    erts_make_ref_in_array(ref);
-    write_ref_thing(hp, ref[0], ref[1], ref[2]);
-
-    return make_internal_ref(hp);
-}
-
-BIF_RETTYPE make_ref_0(BIF_ALIST_0)
-{
-    return erts_make_ref(BIF_P);
-}
-
-/**********************************************************************/
-
 /* return the time of day */
 
 BIF_RETTYPE time_0(BIF_ALIST_0)
@@ -4508,6 +4458,28 @@ BIF_RETTYPE system_flag_2(BIF_ALIST_2)
 	    break;
 	}
 #endif
+    } else if (BIF_ARG_1 == am_time_offset
+	       && ERTS_IS_ATOM_STR("finalize", BIF_ARG_2)) {
+	ErtsTimeOffsetState res;
+	erts_smp_proc_unlock(BIF_P, ERTS_PROC_LOCK_MAIN);
+	res = erts_finalize_time_offset();
+        erts_smp_proc_lock(BIF_P, ERTS_PROC_LOCK_MAIN);
+	switch (res) {
+	case ERTS_TIME_OFFSET_PRELIMINARY: {
+	    DECL_AM(preliminary);
+	    BIF_RET(AM_preliminary);
+	}
+	case ERTS_TIME_OFFSET_FINAL: {
+	    DECL_AM(final);
+	    BIF_RET(AM_final);
+	}
+	case ERTS_TIME_OFFSET_VOLATILE: {
+	    DECL_AM(volatile);
+	    BIF_RET(AM_volatile);
+	}
+	default:
+	    ERTS_INTERNAL_ERROR("Unknown state");
+	}
     } else if (ERTS_IS_ATOM_STR("scheduling_statistics", BIF_ARG_1)) {
 	int what;
 	if (ERTS_IS_ATOM_STR("disable", BIF_ARG_2))
@@ -4795,11 +4767,6 @@ void erts_init_trap_export(Export* ep, Eterm m, Eterm f, Uint a,
 
 void erts_init_bif(void)
 {
-    reference0 = 0;
-    reference1 = 0;
-    reference2 = 0;
-
-    erts_smp_spinlock_init(&make_ref_lock, "make_ref");
     erts_smp_mtx_init(&ports_snapshot_mtx, "ports_snapshot");
     erts_smp_atomic_init_nob(&erts_dead_ports_ptr, (erts_aint_t) NULL);
 
@@ -4816,9 +4783,13 @@ void erts_init_bif(void)
 #endif
 		     , &bif_return_trap);
 
-    flush_monitor_message_trap = erts_export_put(am_erlang,
-						 am_flush_monitor_message,
-						 2);
+    flush_monitor_messages_trap = erts_export_put(am_erts_internal,
+						  am_flush_monitor_messages,
+						  3);
+
+    erts_convert_time_unit_trap = erts_export_put(am_erlang,
+						  am_convert_time_unit,
+						  3);
 
     set_cpu_topology_trap = erts_export_put(am_erlang,
 					    am_set_cpu_topology,
diff --git a/erts/emulator/beam/bif.h b/erts/emulator/beam/bif.h
index 72c55ccb55..bd0f8cda2b 100644
--- a/erts/emulator/beam/bif.h
+++ b/erts/emulator/beam/bif.h
@@ -21,6 +21,7 @@
 #define __BIF_H__
 
 extern Export* erts_format_cpu_topology_trap;
+extern Export *erts_convert_time_unit_trap;
 
 #define BIF_RETTYPE Eterm
 
diff --git a/erts/emulator/beam/bif.tab b/erts/emulator/beam/bif.tab
index e68b8e6274..db8feb681b 100644
--- a/erts/emulator/beam/bif.tab
+++ b/erts/emulator/beam/bif.tab
@@ -92,6 +92,8 @@ bif erlang:loaded/0
 bif erlang:localtime/0
 bif erlang:localtime_to_universaltime/2
 bif erlang:make_ref/0
+bif erlang:unique_integer/0
+bif erlang:unique_integer/1
 bif erlang:md5/1
 bif erlang:md5_init/0
 bif erlang:md5_update/2
@@ -104,6 +106,13 @@ ubif erlang:node/1
 ubif erlang:node/0
 bif erlang:nodes/1
 bif erlang:now/0
+bif erlang:monotonic_time/0
+bif erlang:monotonic_time/1
+bif erlang:system_time/0
+bif erlang:system_time/1
+bif erlang:time_offset/0
+bif erlang:time_offset/1
+bif erlang:timestamp/0
 
 bif erlang:open_port/2
 
@@ -158,6 +167,15 @@ bif erts_internal:check_process_code/2
 
 bif erts_internal:map_to_tuple_keys/1
 
+bif erts_internal:time_unit/0
+
+bif erts_internal:get_bif_timer_servers/0
+bif erts_internal:create_bif_timer/0
+bif erts_internal:access_bif_timer/1
+
+bif erts_internal:monitor_process/2
+bif erts_internal:is_system_process/1
+
 # inet_db support
 bif erlang:port_set_data/2
 bif erlang:port_get_data/1
@@ -347,6 +365,8 @@ bif os:getenv/0
 bif os:getenv/1
 bif os:getpid/0
 bif os:timestamp/0
+bif os:system_time/0
+bif os:system_time/1
 
 #
 # Bifs in the erl_ddll module (the module actually does not exist)
diff --git a/erts/emulator/beam/big.c b/erts/emulator/beam/big.c
index de7d370938..30e6a2c522 100644
--- a/erts/emulator/beam/big.c
+++ b/erts/emulator/beam/big.c
@@ -1577,6 +1577,46 @@ Eterm erts_sint64_to_big(Sint64 x, Eterm **hpp)
     return make_big(hp);
 }
 
+Eterm
+erts_uint64_array_to_big(Uint **hpp, int neg, int len, Uint64 *array)
+{
+    Uint *headerp;
+    int i, pot_digits, digits;
+
+    headerp = *hpp;
+
+    pot_digits = digits = 0;
+    for (i = 0; i < len; i++) {
+#if defined(ARCH_32) || HALFWORD_HEAP
+	Uint low_val = array[i] & ((Uint) 0xffffffff);
+	Uint high_val = (array[i] >> 32) & ((Uint) 0xffffffff);
+	BIG_DIGIT(headerp, pot_digits) = low_val;
+	pot_digits++;
+	if (low_val)
+	    digits = pot_digits;
+	BIG_DIGIT(headerp, pot_digits) = high_val;
+	pot_digits++;
+	if (high_val)
+	    digits = pot_digits;
+#else
+	Uint val = array[i];
+	BIG_DIGIT(headerp, pot_digits) = val;
+	pot_digits++;
+	if (val)
+	    digits = pot_digits;
+#endif
+    }	
+
+    if (neg)
+	*headerp = make_neg_bignum_header(digits);
+    else
+	*headerp = make_pos_bignum_header(digits);
+
+    *hpp = headerp + 1 + digits;
+
+    return make_big(headerp);
+}
+
 /*
 ** Convert a bignum to a double float
 */
diff --git a/erts/emulator/beam/big.h b/erts/emulator/beam/big.h
index da31876d75..4e4611de16 100644
--- a/erts/emulator/beam/big.h
+++ b/erts/emulator/beam/big.h
@@ -104,6 +104,9 @@ typedef Uint  dsize_t;	 /* Vector size type */
    : ERTS_UINT64_BIG_HEAP_SIZE__((X) >= 0 ? (X) : -(Uint64)(X)))
 #define ERTS_UINT64_HEAP_SIZE(X)				\
   (IS_USMALL(0, (X)) ? 0 : ERTS_UINT64_BIG_HEAP_SIZE__((X)))
+#define ERTS_MAX_SINT64_HEAP_SIZE (1 + 2)
+#define ERTS_MAX_UINT64_HEAP_SIZE (1 + 2)
+#define ERTS_UINT64_ARRAY_TO_BIG_MAX_HEAP_SZ(LEN) (2*(LEN)+1)
 
 #else
 
@@ -111,6 +114,9 @@ typedef Uint  dsize_t;	 /* Vector size type */
   (IS_SSMALL((X)) ? 0 : (1 + 1))
 #define ERTS_UINT64_HEAP_SIZE(X)				\
   (IS_USMALL(0, (X)) ? 0 : (1 + 1))
+#define ERTS_MAX_SINT64_HEAP_SIZE (1 + 1)
+#define ERTS_MAX_UINT64_HEAP_SIZE (1 + 1)
+#define ERTS_UINT64_ARRAY_TO_BIG_MAX_HEAP_SZ(LEN) ((LEN)+1)
 
 #endif
 
@@ -156,6 +162,7 @@ int term_to_Uint(Eterm, Uint*);
 int term_to_UWord(Eterm, UWord*);
 int term_to_Sint(Eterm, Sint*);
 #if HAVE_INT64
+Eterm erts_uint64_array_to_big(Uint **, int, int, Uint64 *);
 int term_to_Uint64(Eterm, Uint64*);
 int term_to_Sint64(Eterm, Sint64*);
 #endif
diff --git a/erts/emulator/beam/erl_alloc.types b/erts/emulator/beam/erl_alloc.types
index 21434eb117..4cd4ad100c 100644
--- a/erts/emulator/beam/erl_alloc.types
+++ b/erts/emulator/beam/erl_alloc.types
@@ -269,6 +269,7 @@ type    BUSY_CALLER_TAB	SHORT_LIVED	SYSTEM		busy_caller_table
 type    BUSY_CALLER	SHORT_LIVED	SYSTEM		busy_caller
 type	PROC_SYS_TSK	SHORT_LIVED	PROCESSES	proc_sys_task
 type	PROC_SYS_TSK_QS	SHORT_LIVED	PROCESSES	proc_sys_task_queues
+type    NEW_TIME_OFFSET	SHORT_LIVED	SYSTEM		new_time_offset
 
 +if threads_no_smp
 # Need thread safe allocs, but std_alloc and fix_alloc are not;
diff --git a/erts/emulator/beam/erl_bif_binary.c b/erts/emulator/beam/erl_bif_binary.c
index 3bf78adce7..68004a7725 100644
--- a/erts/emulator/beam/erl_bif_binary.c
+++ b/erts/emulator/beam/erl_bif_binary.c
@@ -36,6 +36,7 @@
 #include "big.h"
 #include "erl_binary.h"
 #include "erl_bits.h"
+#include "erl_bif_unique.h"
 
 
 /*
diff --git a/erts/emulator/beam/erl_bif_ddll.c b/erts/emulator/beam/erl_bif_ddll.c
index 56cd2ba04f..fc4f819f56 100644
--- a/erts/emulator/beam/erl_bif_ddll.c
+++ b/erts/emulator/beam/erl_bif_ddll.c
@@ -45,6 +45,7 @@
 #include "big.h"
 #include "dist.h"
 #include "erl_version.h"
+#include "erl_bif_unique.h"
 #include "dtrace-wrapper.h"
 
 #ifdef ERTS_SMP
diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index b90362d82c..80d49c7ce2 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -42,6 +42,7 @@
 #include "erl_cpu_topology.h"
 #include "erl_async.h"
 #include "erl_thr_progress.h"
+#include "erl_bif_unique.h"
 #define ERTS_PTAB_WANT_DEBUG_FUNCS__
 #include "erl_ptab.h"
 #ifdef HIPE
@@ -2099,6 +2100,46 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
 	BIF_RET(am_opt);
 #endif
 	BIF_RET(res);
+    } else if (BIF_ARG_1 == am_time_offset) {
+	switch (erts_time_offset_state()) {
+	case ERTS_TIME_OFFSET_PRELIMINARY: {
+	    ERTS_DECL_AM(preliminary);
+	    BIF_RET(AM_preliminary);
+	}
+	case ERTS_TIME_OFFSET_FINAL: {
+	    ERTS_DECL_AM(final);
+	    BIF_RET(AM_final);
+	}
+	case ERTS_TIME_OFFSET_VOLATILE: {
+	    ERTS_DECL_AM(volatile);
+	    BIF_RET(AM_volatile);
+	}
+	default:
+	    ERTS_INTERNAL_ERROR("Invalid time offset state");
+	}
+    } else if (ERTS_IS_ATOM_STR("os_monotonic_time_source", BIF_ARG_1)) {
+	BIF_RET(erts_monotonic_time_source(BIF_P));
+    } else if (ERTS_IS_ATOM_STR("time_correction", BIF_ARG_1)) {
+	BIF_RET(erts_has_time_correction() ? am_true : am_false);
+    } else if (ERTS_IS_ATOM_STR("start_time", BIF_ARG_1)) {
+	BIF_RET(erts_get_monotonic_start_time(BIF_P));
+    } else if (ERTS_IS_ATOM_STR("time_warp_mode", BIF_ARG_1)) {
+	switch (erts_time_warp_mode()) {
+	case ERTS_NO_TIME_WARP_MODE: {
+	    ERTS_DECL_AM(no_time_warp);
+	    BIF_RET(AM_no_time_warp);
+	}
+	case ERTS_SINGLE_TIME_WARP_MODE: {
+	    ERTS_DECL_AM(single_time_warp);
+	    BIF_RET(AM_single_time_warp);
+	}
+	case ERTS_MULTI_TIME_WARP_MODE: {
+	    ERTS_DECL_AM(multi_time_warp);
+	    BIF_RET(AM_multi_time_warp);
+	}
+	default:
+	    ERTS_INTERNAL_ERROR("Invalid time warp mode");
+	}
     } else if (BIF_ARG_1 == am_allocated_areas) {
 	res = erts_allocated_areas(NULL, NULL, BIF_P);
 	BIF_RET(res);
@@ -2700,9 +2741,11 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
         BIF_RET(make_small(erts_db_get_max_tabs()));
     }
     else if (ERTS_IS_ATOM_STR("tolerant_timeofday",BIF_ARG_1)) {
-	BIF_RET(erts_disable_tolerant_timeofday
-		? am_disabled
-		: am_enabled);
+	if (erts_has_time_correction()
+	    && erts_time_offset_state() == ERTS_TIME_OFFSET_FINAL) {
+	    BIF_RET(am_enabled);
+	}
+	BIF_RET(am_disabled);
     }
     else if (ERTS_IS_ATOM_STR("eager_check_io",BIF_ARG_1)) {
 	BIF_RET(erts_eager_check_io ? am_true : am_false);
@@ -3400,6 +3443,29 @@ BIF_RETTYPE erts_debug_get_internal_state_1(BIF_ALIST_1)
         else if (ERTS_IS_ATOM_STR("mmap", BIF_ARG_1)) {
             BIF_RET(erts_mmap_debug_info(BIF_P));
         }
+	else if (ERTS_IS_ATOM_STR("unique_monotonic_integer_state", BIF_ARG_1)) {
+	    BIF_RET(erts_debug_get_unique_monotonic_integer_state(BIF_P));
+	}
+	else if (ERTS_IS_ATOM_STR("min_unique_monotonic_integer", BIF_ARG_1)) {
+	    Sint64 value = erts_get_min_unique_monotonic_integer();
+	    if (IS_SSMALL(value))
+		BIF_RET(make_small(value));
+	    else {
+		Uint hsz = ERTS_SINT64_HEAP_SIZE(value);
+		Eterm *hp = HAlloc(BIF_P, hsz);
+		BIF_RET(erts_sint64_to_big(value, &hp));
+	    }
+	}
+	else if (ERTS_IS_ATOM_STR("min_unique_integer", BIF_ARG_1)) {
+	    Sint64 value = erts_get_min_unique_integer();
+	    if (IS_SSMALL(value))
+		BIF_RET(make_small(value));
+	    else {
+		Uint hsz = ERTS_SINT64_HEAP_SIZE(value);
+		Eterm *hp = HAlloc(BIF_P, hsz);
+		BIF_RET(erts_sint64_to_big(value, &hp));
+	    }
+	}
     }
     else if (is_tuple(BIF_ARG_1)) {
 	Eterm* tp = tuple_val(BIF_ARG_1);
@@ -3596,6 +3662,38 @@ BIF_RETTYPE erts_debug_get_internal_state_1(BIF_ALIST_1)
 	    }
 	    break;
 	}
+	case 3: {
+	    if (ERTS_IS_ATOM_STR("check_time_config", tp[1])) {
+		int res, time_correction;
+		ErtsTimeWarpMode time_warp_mode;
+		if (tp[2] == am_true)
+		    time_correction = !0;
+		else if (tp[2] == am_false)
+		    time_correction = 0;
+		else
+		    break;
+		if (ERTS_IS_ATOM_STR("no_time_warp", tp[3]))
+		    time_warp_mode = ERTS_NO_TIME_WARP_MODE;
+		else if (ERTS_IS_ATOM_STR("single_time_warp", tp[3]))
+		    time_warp_mode = ERTS_SINGLE_TIME_WARP_MODE;
+		else if (ERTS_IS_ATOM_STR("multi_time_warp", tp[3]))
+		    time_warp_mode = ERTS_MULTI_TIME_WARP_MODE;
+		else
+		    break;
+		res = erts_check_time_adj_support(time_correction,
+						  time_warp_mode);
+		BIF_RET(res ? am_true : am_false);
+	    }
+	    else if (ERTS_IS_ATOM_STR("make_unique_integer", tp[1])) {
+	      Eterm res = erts_debug_make_unique_integer(BIF_P,
+							 tp[2],
+							 tp[3]);
+	      if (is_non_value(res))
+		  break;
+	      BIF_RET(res);
+	    }
+	    break;
+	}
 	default:
 	    break;
 	}
@@ -3897,6 +3995,10 @@ BIF_RETTYPE erts_debug_set_internal_state_2(BIF_ALIST_2)
 		}
 	    }
 	}
+	else if (ERTS_IS_ATOM_STR("unique_monotonic_integer_state", BIF_ARG_1)) {
+	    int res = erts_debug_set_unique_monotonic_integer_state(BIF_ARG_2);
+	    BIF_RET(res ? am_true : am_false);
+	}
     }
 
     BIF_ERROR(BIF_P, BADARG);
diff --git a/erts/emulator/beam/erl_bif_timer.c b/erts/emulator/beam/erl_bif_timer.c
index 03ac97283c..c9b02b48f5 100644
--- a/erts/emulator/beam/erl_bif_timer.c
+++ b/erts/emulator/beam/erl_bif_timer.c
@@ -27,6 +27,7 @@
 #include "error.h"
 #include "big.h"
 #include "erl_thr_progress.h"
+#include "erl_bif_unique.h"
 
 /****************************************************************************
 ** BIF Timer support
diff --git a/erts/emulator/beam/erl_bif_trace.c b/erts/emulator/beam/erl_bif_trace.c
index 06fbbea123..08796df912 100644
--- a/erts/emulator/beam/erl_bif_trace.c
+++ b/erts/emulator/beam/erl_bif_trace.c
@@ -38,6 +38,7 @@
 #include "beam_bp.h"
 #include "erl_binary.h"
 #include "erl_thr_progress.h"
+#include "erl_bif_unique.h"
 
 #define DECL_AM(S) Eterm AM_ ## S = am_atom_put(#S, sizeof(#S) - 1)
 
diff --git a/erts/emulator/beam/erl_bif_unique.c b/erts/emulator/beam/erl_bif_unique.c
new file mode 100644
index 0000000000..57b0bab72f
--- /dev/null
+++ b/erts/emulator/beam/erl_bif_unique.c
@@ -0,0 +1,556 @@
+/*
+ * %CopyrightBegin%
+ *
+ * Copyright Ericsson AB 2014. All Rights Reserved.
+ *
+ * The contents of this file are subject to the Erlang Public License,
+ * Version 1.1, (the "License"); you may not use this file except in
+ * compliance with the License. You should have received a copy of the
+ * Erlang Public License along with this software. If not, it can be
+ * retrieved online at http://www.erlang.org/.
+ *
+ * Software distributed under the License is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ * the License for the specific language governing rights and limitations
+ * under the License.
+ *
+ * %CopyrightEnd%
+ */
+
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif
+
+#include "sys.h"
+#include "erl_vm.h"
+#include "erl_alloc.h"
+#include "export.h"
+#include "bif.h"
+#include "erl_bif_unique.h"
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
+ * Reference                                                         *
+\*                                                                   */
+
+static union {
+    erts_atomic64_t count;
+    char align__[ERTS_CACHE_LINE_SIZE];
+} global_reference erts_align_attribute(ERTS_CACHE_LINE_SIZE);
+
+
+/*
+ * ref[0] indicate thread creating reference as follows:
+ *
+ * - ref[0] == 0 => Non-scheduler thread;
+ * - else; ref[0] <= erts_no_schedulers =>
+ *      ordinary scheduler with id == ref[0];
+ * - else; ref[0] <= erts_no_schedulers
+ *                   + erts_no_dirty_cpu_schedulers =>
+ *      dirty cpu scheduler with id == 'ref[0] - erts_no_schedulers';
+ * - else =>
+ *      dirty io scheduler with id == 'ref[0]
+ *                                     - erts_no_schedulers
+ *                                     - erts_no_dirty_cpu_schedulers'
+ */
+
+#ifdef DEBUG
+static Uint32 max_thr_id;
+#endif
+
+static void
+init_reference(void)
+{
+#ifdef DEBUG
+    max_thr_id = (Uint32) erts_no_schedulers;
+#ifdef ERTS_DIRTY_SCHEDULERS
+    max_thr_id += (Uint32) erts_no_dirty_cpu_schedulers;
+    max_thr_id += (Uint32) erts_no_dirty_io_schedulers;
+#endif
+#endif
+    erts_atomic64_init_nob(&global_reference.count, 0);
+}
+
+static ERTS_INLINE void
+global_make_ref_in_array(Uint32 thr_id, Uint32 ref[ERTS_MAX_REF_NUMBERS])
+{
+    Uint64 value;
+
+    value = (Uint64) erts_atomic64_inc_read_mb(&global_reference.count);
+    
+    erts_set_ref_numbers(ref, thr_id, value);
+}
+
+static ERTS_INLINE void
+make_ref_in_array(Uint32 ref[ERTS_MAX_REF_NUMBERS])
+{
+    ErtsSchedulerData *esdp = erts_get_scheduler_data();
+    if (esdp)
+	erts_sched_make_ref_in_array(esdp, ref);
+    else
+	global_make_ref_in_array(0, ref);
+}
+
+void
+erts_make_ref_in_array(Uint32 ref[ERTS_MAX_REF_NUMBERS])
+{
+    make_ref_in_array(ref);
+}
+
+Eterm erts_make_ref_in_buffer(Eterm buffer[REF_THING_SIZE])
+{
+    Eterm* hp = buffer;
+    Uint32 ref[ERTS_MAX_REF_NUMBERS];
+
+    make_ref_in_array(ref);
+    write_ref_thing(hp, ref[0], ref[1], ref[2]);
+    return make_internal_ref(hp);
+}
+
+Eterm erts_make_ref(Process *c_p)
+{
+    Eterm* hp;
+    Uint32 ref[ERTS_MAX_REF_NUMBERS];
+
+    ERTS_SMP_LC_ASSERT(ERTS_PROC_LOCK_MAIN & erts_proc_lc_my_proc_locks(c_p));
+
+    hp = HAlloc(c_p, REF_THING_SIZE);
+
+    make_ref_in_array(ref);
+    write_ref_thing(hp, ref[0], ref[1], ref[2]);
+
+    return make_internal_ref(hp);
+}
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
+ * Unique Integer                                                    *
+\*                                                                   */
+
+static struct {
+    union {
+	struct {
+	    int left_shift;
+	    int right_shift;
+	    Uint64 mask;
+	    Uint64 val0_max;
+	} o;
+	char align__[ERTS_CACHE_LINE_SIZE];
+    } r;
+    union {
+	erts_atomic64_t val1;
+	char align__[ERTS_CACHE_LINE_SIZE];
+    } w;
+} unique_data erts_align_attribute(ERTS_CACHE_LINE_SIZE);
+
+static void
+init_unique_integer(void)
+{
+    int bits;
+    unique_data.r.o.val0_max = (Uint64) erts_no_schedulers;
+#ifdef ERTS_DIRTY_SCHEDULERS
+    unique_data.r.o.val0_max += (Uint64) erts_no_dirty_cpu_schedulers;
+    unique_data.r.o.val0_max += (Uint64) erts_no_dirty_io_schedulers;
+#endif
+    bits = erts_fit_in_bits_int64(unique_data.r.o.val0_max);
+    unique_data.r.o.left_shift = bits;
+    unique_data.r.o.right_shift = 64 - bits;
+    unique_data.r.o.mask = (((Uint64) 1) << bits) - 1;
+    erts_atomic64_init_nob(&unique_data.w.val1, -1);
+}
+
+#define ERTS_MAX_UNIQUE_INT_HEAP_SIZE ERTS_UINT64_ARRAY_TO_BIG_MAX_HEAP_SZ(2)
+
+static ERTS_INLINE Eterm
+bld_unique_integer_term(Eterm **hpp, Uint *szp,
+			Uint64 val0, Uint64 val1,
+			int positive)
+{
+    Uint hsz;
+    Uint64 unique_val[2];
+
+    unique_val[0] = ((Uint64) val0);
+    unique_val[0] |= ((Uint64) val1) << unique_data.r.o.left_shift;
+    unique_val[1] = ((Uint64) val1) >> unique_data.r.o.right_shift;
+    unique_val[1] &= unique_data.r.o.mask;
+
+    if (positive) {
+	unique_val[0]++;
+	if (unique_val[0] == 0)
+	    unique_val[1]++;
+    }
+    else {
+	ASSERT(MIN_SMALL < 0);
+	if (unique_val[1] == 0
+	    && unique_val[0] < ((Uint64) -1*((Sint64) MIN_SMALL))) {
+	    Sint64 s_unique_val = (Sint64) unique_val[0];
+	    s_unique_val += MIN_SMALL;
+	    ASSERT(MIN_SMALL <= s_unique_val && s_unique_val < 0);
+	    if (szp)
+		*szp = 0;
+	    if (!hpp)
+		return THE_NON_VALUE;
+	    return make_small((Sint) s_unique_val);
+	}
+	if (unique_val[0] < ((Uint64) -1*((Sint64) MIN_SMALL))) {
+	    ASSERT(unique_val[1] != 0);
+	    unique_val[1] -= 1;
+	}
+	unique_val[0] += MIN_SMALL;
+    }
+
+    if (!unique_val[1]) {
+	if (unique_val[0] <= MAX_SMALL) {
+	    if (szp)
+		*szp = 0;
+	    if (!hpp)
+		return THE_NON_VALUE;
+	    return make_small((Uint) unique_val[0]);
+	}
+
+	if (szp)
+	    *szp = ERTS_UINT64_HEAP_SIZE(unique_val[0]);
+	if (!hpp)
+	    return THE_NON_VALUE;
+	return erts_uint64_to_big(unique_val[0], hpp);
+    }
+    else {
+	Eterm tmp, *tmp_hp, res;
+	DeclareTmpHeapNoproc(local_heap, 2*ERTS_MAX_UNIQUE_INT_HEAP_SIZE);
+
+	UseTmpHeapNoproc(2*ERTS_MAX_UNIQUE_INT_HEAP_SIZE);
+
+	tmp_hp = local_heap;
+
+	tmp = erts_uint64_array_to_big(&tmp_hp, 0, 2, unique_val);
+	ASSERT(is_big(tmp));
+
+	hsz = big_arity(tmp) + 1;
+
+	ASSERT(hsz <= ERTS_MAX_UNIQUE_INT_HEAP_SIZE);
+
+	if (szp)
+	    *szp = hsz;
+
+	if (!hpp)
+	    res = THE_NON_VALUE;
+	else {
+	    int hix;
+	    Eterm *hp = *hpp;
+	    tmp_hp = big_val(tmp);
+	    for (hix = 0; hix < hsz; hix++)
+		hp[hix] = tmp_hp[hix];
+
+	    *hpp = hp + hsz;
+	    res = make_big(hp);
+	}
+
+	UnUseTmpHeapNoproc(2*ERTS_MAX_UNIQUE_INT_HEAP_SIZE);
+
+	return res;
+    }
+}
+
+static ERTS_INLINE Eterm unique_integer_bif(Process *c_p, int positive)
+{
+    ErtsSchedulerData *esdp;
+    Uint64 thr_id, unique;
+    Uint hsz;
+    Eterm *hp;
+
+    esdp = ERTS_PROC_GET_SCHDATA(c_p);
+    thr_id = (Uint64) esdp->thr_id;
+    unique = esdp->unique++;
+    bld_unique_integer_term(NULL, &hsz, thr_id, unique, positive);
+    hp = hsz ? HAlloc(c_p, hsz) : NULL;
+    return bld_unique_integer_term(&hp, NULL, thr_id, unique, positive);
+}
+
+Uint
+erts_raw_unique_integer_heap_size(Uint64 val[ERTS_UNIQUE_INT_RAW_VALUES])
+{
+    Uint sz;
+    bld_unique_integer_term(NULL, &sz, val[0], val[1], 0);
+    return sz;
+}
+
+Eterm
+erts_raw_make_unique_integer(Eterm **hpp, Uint64 val[ERTS_UNIQUE_INT_RAW_VALUES])
+{
+    return bld_unique_integer_term(hpp, NULL, val[0], val[1], 0);
+}
+
+void
+erts_raw_get_unique_integer(Uint64 val[ERTS_UNIQUE_INT_RAW_VALUES])
+{
+    ErtsSchedulerData *esdp = erts_get_scheduler_data();
+    if (esdp) {
+	val[0] = (Uint64) esdp->thr_id;
+	val[1] = esdp->unique++;
+    }
+    else {
+	val[0] = (Uint64) 0;
+	val[1] = (Uint64) erts_atomic64_inc_read_nob(&unique_data.w.val1);
+    }
+}
+
+
+Sint64
+erts_get_min_unique_integer(void)
+{
+    return (Sint64) MIN_SMALL;
+}
+
+/* --- Debug --- */
+
+Eterm
+erts_debug_make_unique_integer(Process *c_p, Eterm etval0, Eterm etval1)
+{
+    Uint64 val0, val1;
+    Uint hsz;
+    Eterm res, *hp, *end_hp;
+
+    if (!term_to_Uint64(etval0, &val0))
+	return THE_NON_VALUE;
+
+    if (!term_to_Uint64(etval1, &val1))
+	return THE_NON_VALUE;
+
+    bld_unique_integer_term(NULL, &hsz, val0, val1, 0);
+
+    hp = HAlloc(c_p, hsz);
+    end_hp = hp + hsz;
+
+    res = bld_unique_integer_term(&hp, NULL, val0, val1, 0);
+    if (hp != end_hp)
+	ERTS_INTERNAL_ERROR("Heap allocation error");
+
+    return res;
+}
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
+ * Strict Monotonic Counter                                          *
+\*                                                                   */
+
+static struct {
+    union {
+	erts_atomic64_t value;
+	char align__[ERTS_CACHE_LINE_SIZE];
+    } w;
+} raw_unique_monotonic_integer erts_align_attribute(ERTS_CACHE_LINE_SIZE);
+
+#if defined(ARCH_32) || HALFWORD_HEAP
+#  define ERTS_UNIQUE_MONOTONIC_OFFSET ERTS_SINT64_MIN
+#else
+#  define ERTS_UNIQUE_MONOTONIC_OFFSET MIN_SMALL
+#endif
+
+static void
+init_unique_monotonic_integer(void)
+{
+    erts_atomic64_init_nob(&raw_unique_monotonic_integer.w.value,
+			   (erts_aint64_t) -1);
+}
+
+static ERTS_INLINE Uint64
+get_raw_unique_monotonic_integer(void)
+{
+    return (Uint64) erts_atomic64_inc_read_mb(&raw_unique_monotonic_integer.w.value);
+}
+
+static ERTS_INLINE Uint
+get_unique_monotonic_integer_heap_size(Uint64 raw, int positive)
+{
+    if (positive) {
+	Uint64 value = raw+1;
+	return ERTS_UINT64_HEAP_SIZE(value);
+    }
+    else {
+	Sint64 value = ((Sint64) raw) + ERTS_UNIQUE_MONOTONIC_OFFSET;
+	if (IS_SSMALL(value))
+	    return 0;
+#if defined(ARCH_32) || HALFWORD_HEAP
+	return ERTS_SINT64_HEAP_SIZE(value);
+#else
+	return ERTS_UINT64_HEAP_SIZE((Uint64) value);
+#endif
+    }
+}
+
+static ERTS_INLINE Eterm
+make_unique_monotonic_integer_value(Eterm *hp, Uint hsz, Uint64 raw, int positive)
+{
+    Eterm res;
+#ifdef DEBUG
+    Eterm *end_hp = hp + hsz;
+#endif
+
+    if (positive) {
+	Uint64 value = raw+1;
+	res = hsz ? erts_uint64_to_big(value, &hp) : make_small(value);
+    }
+    else {
+	Sint64 value = ((Sint64) raw) + ERTS_UNIQUE_MONOTONIC_OFFSET;
+	if (hsz == 0)
+	    res = make_small(value);
+	else {
+#if defined(ARCH_32) || HALFWORD_HEAP
+	    res = erts_sint64_to_big(value, &hp);
+#else 
+	    res = erts_uint64_to_big((Uint64) value, &hp);
+#endif
+	}
+    }
+
+    ASSERT(end_hp == hp);
+
+    return res;
+}
+
+static ERTS_INLINE Eterm
+unique_monotonic_integer_bif(Process *c_p, int positive)
+{
+    Uint64 raw;
+    Uint hsz;
+    Eterm *hp;
+
+    raw = get_raw_unique_monotonic_integer();
+    hsz = get_unique_monotonic_integer_heap_size(raw, positive);
+    hp = hsz ? HAlloc(c_p, hsz) : NULL;
+    return make_unique_monotonic_integer_value(hp, hsz, raw, positive);
+}
+
+Sint64
+erts_raw_get_unique_monotonic_integer(void)
+{
+    return get_raw_unique_monotonic_integer();
+}
+
+Uint
+erts_raw_unique_monotonic_integer_heap_size(Sint64 raw)
+{
+    return get_unique_monotonic_integer_heap_size(raw, 0);
+}
+
+Eterm
+erts_raw_make_unique_monotonic_integer_value(Eterm **hpp, Sint64 raw)
+{
+    Uint hsz = get_unique_monotonic_integer_heap_size(raw, 0);
+    Eterm res = make_unique_monotonic_integer_value(*hpp, hsz, raw, 0);
+    *hpp += hsz;
+    return res;
+}
+
+Sint64
+erts_get_min_unique_monotonic_integer(void)
+{
+    return ERTS_UNIQUE_MONOTONIC_OFFSET;
+}
+
+/* --- Debug --- */
+
+int
+erts_debug_set_unique_monotonic_integer_state(Eterm et_value)
+{
+    Sint64 value;
+
+    if (!term_to_Sint64(et_value, &value)) {
+	Uint64 uvalue;
+	if (!term_to_Uint64(et_value, &uvalue))
+	    return 0;
+	value = (Sint64) uvalue;
+    }
+
+    erts_atomic64_set_mb(&raw_unique_monotonic_integer.w.value,
+			 (erts_aint64_t) value);
+    return 1;
+}
+
+Eterm
+erts_debug_get_unique_monotonic_integer_state(Process *c_p)
+{
+    Uint64 value;
+    Eterm hsz, *hp;
+
+    value = (Uint64) erts_atomic64_read_mb(&raw_unique_monotonic_integer.w.value);
+
+    if (IS_USMALL(0, value))
+	return make_small(value);
+    hsz = ERTS_UINT64_HEAP_SIZE(value);
+    hp = HAlloc(c_p, hsz);
+    return erts_uint64_to_big(value, &hp);
+}
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
+ * Initilazation                                                     *
+\*                                                                   */
+
+void
+erts_bif_unique_init(void)
+{
+    init_reference();
+    init_unique_monotonic_integer();
+    init_unique_integer();
+}
+
+void
+erts_sched_bif_unique_init(ErtsSchedulerData *esdp)
+{
+    esdp->unique = (Uint64) 0;
+    esdp->ref = (Uint64) 0;
+}
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
+ * The BIFs                                                          *
+\*                                                                   */
+
+
+BIF_RETTYPE make_ref_0(BIF_ALIST_0)
+{
+    BIF_RETTYPE res;
+    Eterm* hp;
+
+    ERTS_SMP_LC_ASSERT(ERTS_PROC_LOCK_MAIN & erts_proc_lc_my_proc_locks(BIF_P));
+
+    hp = HAlloc(BIF_P, REF_THING_SIZE);
+
+    res = erts_sched_make_ref_in_buffer(ERTS_PROC_GET_SCHDATA(BIF_P), hp);
+
+    BIF_RET(res);
+}
+
+BIF_RETTYPE unique_integer_0(BIF_ALIST_0)
+{
+    BIF_RET(unique_integer_bif(BIF_P, 0));
+}
+
+BIF_RETTYPE unique_integer_1(BIF_ALIST_1)
+{
+    Eterm modlist = BIF_ARG_1;
+    int monotonic = 0;
+    int positive = 0;
+    BIF_RETTYPE res;
+
+    while (is_list(modlist)) {
+	Eterm *consp = list_val(modlist);
+	switch (CAR(consp)) {
+	case am_monotonic:
+	    monotonic = 1;
+	    break;
+	case am_positive:
+	    positive = 1;
+	    break;
+	default:
+	    BIF_ERROR(BIF_P, BADARG);
+	}
+	modlist = CDR(consp);
+    }
+
+    if (is_not_nil(modlist))
+	BIF_ERROR(BIF_P, BADARG);
+
+    if (monotonic)
+	res = unique_monotonic_integer_bif(BIF_P, positive);
+    else
+	res = unique_integer_bif(BIF_P, positive);
+
+    BIF_RET(res);
+}
diff --git a/erts/emulator/beam/erl_bif_unique.h b/erts/emulator/beam/erl_bif_unique.h
new file mode 100644
index 0000000000..cd001172a1
--- /dev/null
+++ b/erts/emulator/beam/erl_bif_unique.h
@@ -0,0 +1,131 @@
+/*
+ * %CopyrightBegin%
+ *
+ * Copyright Ericsson AB 2014. All Rights Reserved.
+ *
+ * The contents of this file are subject to the Erlang Public License,
+ * Version 1.1, (the "License"); you may not use this file except in
+ * compliance with the License. You should have received a copy of the
+ * Erlang Public License along with this software. If not, it can be
+ * retrieved online at http://www.erlang.org/.
+ *
+ * Software distributed under the License is distributed on an "AS IS"
+ * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+ * the License for the specific language governing rights and limitations
+ * under the License.
+ *
+ * %CopyrightEnd%
+ */
+
+#ifndef ERTS_BIF_UNIQUE_H__
+#define ERTS_BIF_UNIQUE_H__
+
+#include "erl_process.h"
+#include "big.h"
+
+void erts_bif_unique_init(void);
+void erts_sched_bif_unique_init(ErtsSchedulerData *esdp);
+
+/* reference */
+Eterm erts_make_ref(Process *);
+Eterm erts_make_ref_in_buffer(Eterm buffer[REF_THING_SIZE]);
+void erts_make_ref_in_array(Uint32 ref[ERTS_MAX_REF_NUMBERS]);
+
+/* strict monotonic counter */
+
+#define ERTS_MAX_UNIQUE_MONOTONIC_INTEGER_HEAP_SIZE ERTS_MAX_UINT64_HEAP_SIZE
+
+/*
+ * Note that a raw value is an intermediate value that 
+ * not necessarily correspond to the end result.
+ */
+Sint64 erts_raw_get_unique_monotonic_integer(void);
+Uint erts_raw_unique_monotonic_integer_heap_size(Sint64 raw);
+Eterm erts_raw_make_unique_monotonic_integer_value(Eterm **hpp, Sint64 raw);
+
+Sint64 erts_get_min_unique_monotonic_integer(void);
+
+int erts_debug_set_unique_monotonic_integer_state(Eterm et_value);
+Eterm erts_debug_get_unique_monotonic_integer_state(Process *c_p);
+
+/* unique integer */
+#define ERTS_UNIQUE_INT_RAW_VALUES 2
+#define ERTS_MAX_UNIQUE_INT_HEAP_SIZE ERTS_UINT64_ARRAY_TO_BIG_MAX_HEAP_SZ(2)
+
+Uint erts_raw_unique_integer_heap_size(Uint64 val[ERTS_UNIQUE_INT_RAW_VALUES]);
+Eterm erts_raw_make_unique_integer(Eterm **hpp, Uint64 val[ERTS_UNIQUE_INT_RAW_VALUES]);
+void erts_raw_get_unique_integer(Uint64 val[ERTS_UNIQUE_INT_RAW_VALUES]);
+Sint64 erts_get_min_unique_integer(void);
+
+Eterm erts_debug_make_unique_integer(Process *c_p,
+				     Eterm etval0,
+				     Eterm etval1);
+
+
+ERTS_GLB_INLINE void erts_set_ref_numbers(Uint32 ref[ERTS_MAX_REF_NUMBERS],
+					  Uint32 thr_id, Uint64 value);
+ERTS_GLB_INLINE Uint32 erts_get_ref_numbers_thr_id(Uint32 ref[ERTS_MAX_REF_NUMBERS]);
+ERTS_GLB_INLINE Uint64 erts_get_ref_numbers_value(Uint32 ref[ERTS_MAX_REF_NUMBERS]);
+ERTS_GLB_INLINE void erts_sched_make_ref_in_array(ErtsSchedulerData *esdp,
+						  Uint32 ref[ERTS_MAX_REF_NUMBERS]);
+ERTS_GLB_INLINE Eterm erts_sched_make_ref_in_buffer(ErtsSchedulerData *esdp,
+						    Eterm buffer[REF_THING_SIZE]);
+
+#if ERTS_GLB_INLINE_INCL_FUNC_DEF
+
+ERTS_GLB_INLINE void
+erts_set_ref_numbers(Uint32 ref[ERTS_MAX_REF_NUMBERS], Uint32 thr_id, Uint64 value)
+{
+    /*
+     * We cannot use thread id in the first 18-bit word since
+     * the hash/phash/phash2 BIFs only hash on this word. If
+     * we did, we would get really poor hash values. Instead
+     * we have to shuffle the bits a bit.
+     */
+    ASSERT(thr_id == (thr_id & ((Uint32) 0x3ffff)));
+    ref[0] = (Uint32) (value & ((Uint64) 0x3ffff));
+    ref[1] = (((Uint32) (value & ((Uint64) 0xfffc0000)))
+	      | (thr_id & ((Uint32) 0x3ffff)));
+    ref[2] = (Uint32) ((value >> 32) & ((Uint64) 0xffffffff));
+}
+
+ERTS_GLB_INLINE Uint32
+erts_get_ref_numbers_thr_id(Uint32 ref[ERTS_MAX_REF_NUMBERS])
+{
+    return ref[1] & ((Uint32) 0x3ffff);
+}
+
+ERTS_GLB_INLINE Uint64
+erts_get_ref_numbers_value(Uint32 ref[ERTS_MAX_REF_NUMBERS])
+{
+    return (((((Uint64) ref[2]) & ((Uint64) 0xffffffff)) << 32)
+	    | (((Uint64) ref[1]) & ((Uint64) 0xfffc0000))
+	    | (((Uint64) ref[0]) & ((Uint64) 0x3ffff)));
+}
+
+ERTS_GLB_INLINE void
+erts_sched_make_ref_in_array(ErtsSchedulerData *esdp,
+			     Uint32 ref[ERTS_MAX_REF_NUMBERS])
+{
+    Uint64 value;
+
+    ASSERT(esdp);
+    value = esdp->ref++;
+    erts_set_ref_numbers(ref, (Uint32) esdp->thr_id, value);
+}
+
+ERTS_GLB_INLINE Eterm
+erts_sched_make_ref_in_buffer(ErtsSchedulerData *esdp,
+			      Eterm buffer[REF_THING_SIZE])
+{
+    Eterm* hp = buffer;
+    Uint32 ref[ERTS_MAX_REF_NUMBERS];
+
+    erts_sched_make_ref_in_array(esdp, ref);
+    write_ref_thing(hp, ref[0], ref[1], ref[2]);
+    return make_internal_ref(hp);
+}
+
+#endif /* ERTS_GLB_INLINE_INCL_FUNC_DEF */
+
+#endif /*  ERTS_BIF_UNIQUE_H__ */
diff --git a/erts/emulator/beam/erl_gc.c b/erts/emulator/beam/erl_gc.c
index 0db42d4325..fea9b16e90 100644
--- a/erts/emulator/beam/erl_gc.c
+++ b/erts/emulator/beam/erl_gc.c
@@ -37,6 +37,7 @@
 #include "hipe_mode_switch.h"
 #endif
 #include "dtrace-wrapper.h"
+#include "erl_bif_unique.h"
 
 #define ERTS_INACT_WR_PB_LEAVE_MUCH_LIMIT 1
 #define ERTS_INACT_WR_PB_LEAVE_MUCH_PERCENTAGE 20
diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index 61f8385efc..0e128c9b99 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -45,6 +45,7 @@
 #include "erl_thr_queue.h"
 #include "erl_async.h"
 #include "erl_ptab.h"
+#include "erl_bif_unique.h"
 
 #ifdef HIPE
 #include "hipe_mode_switch.h"	/* for hipe_mode_switch_init() */
@@ -134,7 +135,9 @@ static void erl_init(int ncpu,
 		     int legacy_proc_tab,
 		     int port_tab_sz,
 		     int port_tab_sz_ignore_files,
-		     int legacy_port_tab);
+		     int legacy_port_tab,
+		     int time_correction,
+		     ErtsTimeWarpMode time_warp_mode);
 
 static erts_atomic_t exiting;
 
@@ -188,10 +191,6 @@ static int no_dirty_io_schedulers;
 Uint32 verbose;             /* See erl_debug.h for information about verbose */
 #endif
 
-int erts_disable_tolerant_timeofday; /* Time correction can be disabled it is
-				      * not and/or it is too slow.
-				      */
-
 int erts_atom_table_size = ATOM_LIMIT;	/* Maximum number of atoms */
 
 int erts_modified_timing_level;
@@ -269,6 +268,19 @@ this_rel_num(void)
     return this_rel;
 }
 
+static ERTS_INLINE void
+set_default_time_adj(int *time_correction_p, ErtsTimeWarpMode *time_warp_mode_p)
+{
+    *time_correction_p = 1;
+    *time_warp_mode_p = ERTS_NO_TIME_WARP_MODE;
+    if (!erts_check_time_adj_support(*time_correction_p,
+				     *time_warp_mode_p)) {
+	*time_correction_p = 0;
+	ASSERT(erts_check_time_adj_support(*time_correction_p,
+					   *time_warp_mode_p));
+    }
+}
+
 /*
  * Common error printout function, all error messages
  * that don't go to the error logger go through here.
@@ -284,13 +296,22 @@ static int early_init(int *argc, char **argv);
 void
 erts_short_init(void)
 {
-    int ncpu = early_init(NULL, NULL);
+    
+    int ncpu;
+    int time_correction;
+    ErtsTimeWarpMode time_warp_mode;
+
+    set_default_time_adj(&time_correction,
+			 &time_warp_mode);
+    ncpu = early_init(NULL, NULL);
     erl_init(ncpu,
 	     ERTS_DEFAULT_MAX_PROCESSES,
 	     0,
 	     ERTS_DEFAULT_MAX_PORTS,
 	     0,
-	     0);
+	     0,
+	     time_correction,
+	     time_warp_mode);
     erts_initialized = 1;
 }
 
@@ -300,12 +321,15 @@ erl_init(int ncpu,
 	 int legacy_proc_tab,
 	 int port_tab_sz,
 	 int port_tab_sz_ignore_files,
-	 int legacy_port_tab)
+	 int legacy_port_tab,
+	 int time_correction,
+	 ErtsTimeWarpMode time_warp_mode)
 {
     init_benchmarking();
 
+    erts_bif_unique_init();
     erts_init_monitors();
-    erts_init_time();
+    erts_init_time(time_correction, time_warp_mode);
     erts_init_sys_common_misc();
     erts_init_process(ncpu, proc_tab_sz, legacy_proc_tab);
     erts_init_scheduling(no_schedulers,
@@ -509,9 +533,9 @@ void erts_usage(void)
 
     /*    erts_fprintf(stderr, "-b func    set the boot function (default boot)\n"); */
 
-    erts_fprintf(stderr, "-c             disable continuous date/time correction with\n");
-    erts_fprintf(stderr, "               respect to uptime\n");
-
+    erts_fprintf(stderr, "-c bool        enable or disable time correction\n");
+    erts_fprintf(stderr, "-C mode        set time warp mode; valid modes are:\n");
+    erts_fprintf(stderr, "               no_time_warp|single_time_warp|multi_time_warp\n");
     erts_fprintf(stderr, "-d             don't write a crash dump for internally detected errors\n");
     erts_fprintf(stderr, "               (halt(String) will still produce a crash dump)\n");
     erts_fprintf(stderr, "-fn[u|a|l]     Control how filenames are interpreted\n");
@@ -681,7 +705,6 @@ early_init(int *argc, char **argv) /*
 
     erts_sched_compact_load = 1;
     erts_printf_eterm_func = erts_printf_term;
-    erts_disable_tolerant_timeofday = 0;
     display_items = 200;
     erts_backtrace_depth = DEFAULT_BACKTRACE_SIZE;
     erts_async_max_threads = ERTS_DEFAULT_NO_ASYNC_THREADS;
@@ -1144,6 +1167,7 @@ early_init(int *argc, char **argv) /*
 
     /* Creates threads on Windows that depend on the arguments, so has to be after erl_sys_args */
     erl_sys_init();
+    erts_early_init_time_sup();
 
     erts_ets_realloc_always_moves = 0;
     erts_ets_always_compress = 0;
@@ -1187,7 +1211,11 @@ erl_start(int argc, char **argv)
     int port_tab_sz_ignore_files = 0;
     int legacy_proc_tab = 0;
     int legacy_port_tab = 0;
+    int time_correction;
+    ErtsTimeWarpMode time_warp_mode;
 
+    set_default_time_adj(&time_correction,
+			 &time_warp_mode);
 
     envbufsz = sizeof(envbuf);
     if (erts_sys_getenv_raw(ERL_MAX_ETS_TABLES_ENV, envbuf, &envbufsz) == 0)
@@ -1896,15 +1924,56 @@ erl_start(int argc, char **argv)
 	    }
 	    break;
 	}
-	case 'c':
-	    if (argv[i][2] == 0) { /* -c: documented option */
-		erts_disable_tolerant_timeofday = 1;
+	case 'C':
+	    arg = get_arg(argv[i]+2, argv[i+1], &i);
+	    if (sys_strcmp(arg, "no_time_warp") == 0)
+		time_warp_mode = ERTS_NO_TIME_WARP_MODE;
+	    else if (sys_strcmp(arg, "single_time_warp") == 0)
+		time_warp_mode = ERTS_SINGLE_TIME_WARP_MODE;
+	    else if (sys_strcmp(arg, "multi_time_warp") == 0)
+		time_warp_mode = ERTS_MULTI_TIME_WARP_MODE;
+	    else {
+		erts_fprintf(stderr,
+			     "Invalid time warp mode: %s\n", arg);
+		erts_usage();
 	    }
+	    break;
+	case 'c':
+	    if (sys_strcmp(argv[i]+2, "false") == 0)
+		goto time_correction_false;
+	    else if (sys_strcmp(argv[i]+2, "true") == 0)
+		goto time_correction_true;
 #ifdef ERTS_OPCODE_COUNTER_SUPPORT
 	    else if (argv[i][2] == 'i') { /* -ci: undcoumented option*/
 		count_instructions = 1;
 	    }
 #endif
+	    else if (argv[i][2] == '\0') {
+		if (i + 1 >= argc)
+		    goto time_correction_false;
+		else {
+		    if (sys_strcmp(argv[i+1], "false") == 0) {
+			(void) get_arg(argv[i]+2, argv[i+1], &i);
+			goto time_correction_false;
+		    }
+		    else if (sys_strcmp(argv[i+1], "true") == 0) {
+			(void) get_arg(argv[i]+2, argv[i+1], &i);
+		    time_correction_true:
+			time_correction = 1;
+			break;
+		    }
+		    else {
+		    time_correction_false:
+			time_correction = 0;
+			break;
+		    }
+		}
+	    }
+	    else {
+		arg = get_arg(argv[i]+2, argv[i+1], &i);
+		erts_fprintf(stderr, "Invalid time correnction value: %s\n", arg);
+		erts_usage();
+	    }
 	    break;
 	case 'W':
 	    arg = get_arg(argv[i]+2, argv[i+1], &i);
@@ -1950,6 +2019,30 @@ erl_start(int argc, char **argv)
 	i++;
     }
 
+    if (!erts_check_time_adj_support(time_correction, time_warp_mode)) {
+	char *time_correction_str = time_correction ? "Enabled" : "Disabled";
+	char *time_warp_str = "undefined";
+	switch (time_warp_mode) {
+	case ERTS_NO_TIME_WARP_MODE:
+	    time_warp_str = "no";
+	    break;
+	case ERTS_SINGLE_TIME_WARP_MODE:
+	    time_warp_str = "single";
+	    break;
+	case ERTS_MULTI_TIME_WARP_MODE:
+	    time_warp_str = "multi";
+	    break;
+	default:
+	    time_warp_str = "undefined";
+	    break;
+	}
+	erts_fprintf(stderr, "%s time correction with %s time warp mode "
+		     "is not supported on this platform\n",
+		     time_correction_str,
+		     time_warp_str);
+	erts_usage();
+    }
+
 /* Output format on windows for sprintf defaults to three exponents.
  * We use two-exponent to mimic normal sprintf behaviour.
  */
@@ -1983,7 +2076,9 @@ erl_start(int argc, char **argv)
 	     legacy_proc_tab,
 	     port_tab_sz,
 	     port_tab_sz_ignore_files,
-	     legacy_port_tab);
+	     legacy_port_tab,
+	     time_correction,
+	     time_warp_mode);
 
     load_preloaded();
     erts_end_staging_code_ix();
diff --git a/erts/emulator/beam/erl_lock_check.c b/erts/emulator/beam/erl_lock_check.c
index b105ece6f1..261460d054 100644
--- a/erts/emulator/beam/erl_lock_check.c
+++ b/erts/emulator/beam/erl_lock_check.c
@@ -140,7 +140,6 @@ static erts_lc_lock_order_t erts_lock_order[] = {
     {	"async_enq_mtx",			NULL			},
 #ifdef ERTS_SMP
     {	"atom_tab",				NULL			},
-    {	"make_ref",				NULL			},
     {	"misc_op_list_pre_alloc_lock",		"address"		},
     {	"message_pre_alloc_lock",		"address"		},
     {	"ptimer_pre_alloc_lock",		"address",		},
@@ -168,6 +167,8 @@ static erts_lc_lock_order_t erts_lock_order[] = {
     {	"timer_wheel",				NULL			},
     {	"system_block",				NULL			},
     {	"timeofday",				NULL			},
+    {	"get_time",				NULL			},
+    {	"get_corrected_time",			NULL			},
     {	"breakpoints",				NULL			},
     {	"pollsets_lock",			NULL			},
     {	"pix_lock",				"address"		},
@@ -184,10 +185,8 @@ static erts_lc_lock_order_t erts_lock_order[] = {
     {   "efile_drv dtrace mutex",               NULL                    },
 #endif
     {	"mtrace_buf",				NULL			},
-#ifdef __WIN32__
 #ifdef ERTS_SMP
-    {   "sys_gethrtime",                        NULL                    },
-#endif
+    {	"os_monotonic_time",			NULL			},
 #endif
     {	"erts_alloc_hard_debug",		NULL			},
     {	"hard_dbg_mseg",		        NULL	                },
diff --git a/erts/emulator/beam/erl_lock_count.c b/erts/emulator/beam/erl_lock_count.c
index cf6996ea06..ddeb56a6be 100644
--- a/erts/emulator/beam/erl_lock_count.c
+++ b/erts/emulator/beam/erl_lock_count.c
@@ -104,11 +104,10 @@ static void lcnt_clear_stats(erts_lcnt_lock_stats_t *stats) {
 }
 
 static void lcnt_time(erts_lcnt_time_t *time) {
-#if 0 || defined(HAVE_GETHRTIME)
-    SysHrTime hr_time;
-    hr_time  = sys_gethrtime();
-    time->s  = (unsigned long)(hr_time / 1000000000LL);
-    time->ns = (unsigned long)(hr_time - 1000000000LL*time->s);
+#if 0 || defined(ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT)
+    ErtsMonotonicTime mtime = ERTS_MONOTONIC_TO_NSEC(erts_os_monotonic_time());
+    time->s  = (unsigned long) (mtime / 1000000000LL);
+    time->ns = (unsigned long) (mtime - 1000000000LL*time->s);
 #else
   SysTimeval tv;
   sys_gettimeofday(&tv);
diff --git a/erts/emulator/beam/erl_lock_count.h b/erts/emulator/beam/erl_lock_count.h
index ffbb93da1b..09fadd7e9e 100644
--- a/erts/emulator/beam/erl_lock_count.h
+++ b/erts/emulator/beam/erl_lock_count.h
@@ -76,7 +76,7 @@
 
 /* histogram */
 #define ERTS_LCNT_HISTOGRAM_MAX_NS    (((unsigned long)1LL << 28) - 1)
-#if 0 || defined(HAVE_GETHRTIME)
+#if 0 || defined(ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT)
 #define ERTS_LCNT_HISTOGRAM_SLOT_SIZE (30)
 #define ERTS_LCNT_HISTOGRAM_RSHIFT    (0)
 #else
diff --git a/erts/emulator/beam/erl_monitors.h b/erts/emulator/beam/erl_monitors.h
index fb11dbbd22..9972890db7 100644
--- a/erts/emulator/beam/erl_monitors.h
+++ b/erts/emulator/beam/erl_monitors.h
@@ -82,6 +82,7 @@
 /* Type tags for monitors */
 #define MON_ORIGIN 1
 #define MON_TARGET 3
+#define MON_TIME_OFFSET 7
 
 /* Type tags for links */
 #define LINK_PID 1   /* ...Or port */
@@ -103,7 +104,7 @@ typedef struct erts_monitor_or_link {
 typedef struct erts_monitor {
     struct erts_monitor *left, *right; 
     Sint16 balance;
-    Uint16 type;  /* MON_ORIGIN | MON_TARGET */
+    Uint16 type;  /* MON_ORIGIN | MON_TARGET | MON_TIME_OFFSET */
     Eterm ref;
     Eterm pid;    /* In case of distributed named monitor, this is the
 		     nodename atom in MON_ORIGIN process, otherwise a pid or
diff --git a/erts/emulator/beam/erl_nif.c b/erts/emulator/beam/erl_nif.c
index adc3520ebb..47d0af16bc 100644
--- a/erts/emulator/beam/erl_nif.c
+++ b/erts/emulator/beam/erl_nif.c
@@ -36,6 +36,7 @@
 #include "erl_thr_progress.h"
 #include "dtrace-wrapper.h"
 #include "erl_process.h"
+#include "erl_bif_unique.h"
 #if defined(USE_DYNAMIC_TRACE) && (defined(USE_DTRACE) || defined(USE_SYSTEMTAP))
 #define HAVE_USE_DTRACE 1
 #endif
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index ea63d20dfa..81bc3d2429 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -43,6 +43,7 @@
 #include "erl_async.h"
 #include "dtrace-wrapper.h"
 #include "erl_ptab.h"
+#include "erl_bif_unique.h"
 
 
 #define ERTS_DELAYED_WAKEUP_INFINITY (~(Uint64) 0)
@@ -702,8 +703,8 @@ init_sched_wall_time(ErtsSchedWallTime *swtp)
 static ERTS_INLINE Uint64
 sched_wall_time_ts(void)
 {
-#ifdef HAVE_GETHRTIME
-    return (Uint64) sys_gethrtime();
+#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+    return (Uint64) erts_os_monotonic_time();
 #else
     Uint64 res;
     SysTimeval tv;
@@ -2843,7 +2844,6 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
     else
 #endif
     {
-	erts_aint_t dt;
 
 	erts_smp_atomic32_set_relb(&function_calls, 0);
 	*fcalls = 0;
@@ -2868,6 +2868,7 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 	    goto sys_aux_work;
 
 	while (spincount-- > 0) {
+	    ErtsMonotonicTime current_time;
 
 	sys_poll_aux_work:
 
@@ -2877,8 +2878,9 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 	    ASSERT(!erts_port_task_have_outstanding_io_tasks());
 	    erl_sys_schedule(1); /* Might give us something to do */
 
-	    dt = erts_do_time_read_and_reset();
-	    if (dt) erts_bump_timer(dt);
+	    current_time = erts_get_monotonic_time();
+	    if (current_time >= erts_next_timeout_time())
+		erts_bump_timers(current_time);
 
 	sys_aux_work:
 #ifndef ERTS_SMP
@@ -2993,8 +2995,11 @@ scheduler_wait(int *fcalls, ErtsSchedulerData *esdp, ErtsRunQueue *rq)
 
 	erl_sys_schedule(0);
 
-	dt = erts_do_time_read_and_reset();
-	if (dt) erts_bump_timer(dt);
+	{
+	    ErtsMonotonicTime current_time = erts_get_monotonic_time();
+	    if (current_time >= erts_next_timeout_time())
+		erts_bump_timers(current_time);
+	}
 
 #ifndef ERTS_SMP
 	if (rq->len == 0 && !rq->misc.start)
@@ -5276,6 +5281,9 @@ init_scheduler_data(ErtsSchedulerData* esdp, int num,
     esdp->run_queue = runq;
     esdp->run_queue->scheduler = esdp;
 
+    esdp->thr_id = (Uint32) num;
+    erts_sched_bif_unique_init(esdp);
+
     if (daww_ptr) {
 	init_aux_work_data(&esdp->aux_work_data, esdp, *daww_ptr);
 #ifdef ERTS_SMP
@@ -7717,6 +7725,8 @@ sched_dirty_cpu_thread_func(void *vesdp)
     callbacks.wait = NULL;
     callbacks.finalize_wait = NULL;
 
+    esdp->thr_id += erts_no_schedulers;
+
     erts_thr_progress_register_unmanaged_thread(&callbacks);
 #ifdef ERTS_ENABLE_LOCK_CHECK
     {
@@ -7778,6 +7788,8 @@ sched_dirty_io_thread_func(void *vesdp)
     callbacks.wait = NULL;
     callbacks.finalize_wait = NULL;
 
+    esdp->thr_id += erts_no_schedulers + erts_no_dirty_cpu_schedulers;
+
     erts_thr_progress_register_unmanaged_thread(&callbacks);
 #ifdef ERTS_ENABLE_LOCK_CHECK
     {
@@ -8897,7 +8909,6 @@ Process *schedule(Process *p, int calls)
 {
     Process *proxy_p = NULL;
     ErtsRunQueue *rq;
-    erts_aint_t dt;
     ErtsSchedulerData *esdp;
     int context_reds;
     int fcalls;
@@ -9027,11 +9038,13 @@ Process *schedule(Process *p, int calls)
 
 	ERTS_SMP_CHK_NO_PROC_LOCKS;
 
-	dt = erts_do_time_read_and_reset();
-	if (dt) {
-	    erts_smp_runq_unlock(rq);
-	    erts_bump_timer(dt);
-	    erts_smp_runq_lock(rq);
+	{
+	    ErtsMonotonicTime current_time = erts_get_monotonic_time();
+	    if (current_time >= erts_next_timeout_time()) {
+		erts_smp_runq_unlock(rq);
+		erts_bump_timers(current_time);
+		erts_smp_runq_lock(rq);
+	    }
 	}
 	BM_STOP_TIMER(system);
 
@@ -9177,6 +9190,7 @@ Process *schedule(Process *p, int calls)
 	else if (!ERTS_SCHEDULER_IS_DIRTY(esdp) &&
 		 (fcalls > input_reductions &&
 		  prepare_for_sys_schedule(esdp, !0))) {
+	    ErtsMonotonicTime current_time;
 	    /*
 	     * Schedule system-level activities.
 	     */
@@ -9189,8 +9203,10 @@ Process *schedule(Process *p, int calls)
 #endif
 	    erts_smp_runq_unlock(rq);
 	    erl_sys_schedule(1);
-	    dt = erts_do_time_read_and_reset();
-	    if (dt) erts_bump_timer(dt);
+
+	    current_time = erts_get_monotonic_time();
+	    if (current_time >= erts_next_timeout_time())
+		erts_bump_timers(current_time);
 
 #ifdef ERTS_SMP
 	    erts_smp_runq_lock(rq);
@@ -11501,7 +11517,8 @@ static void doit_exit_monitor(ErtsMonitor *mon, void *vpcontext)
     ErtsMonitor *rmon;
     Process *rp;
 
-    if (mon->type == MON_ORIGIN) {
+    switch (mon->type) {
+    case MON_ORIGIN:
 	/* We are monitoring someone else, we need to demonitor that one.. */
 	if (is_atom(mon->pid)) { /* remote by name */
 	    ASSERT(is_node_name_atom(mon->pid));
@@ -11564,7 +11581,8 @@ static void doit_exit_monitor(ErtsMonitor *mon, void *vpcontext)
 		}
 	    }
 	}
-    } else { /* type == MON_TARGET */
+	break;
+    case MON_TARGET:
 	ASSERT(mon->type == MON_TARGET);
 	ASSERT(is_pid(mon->pid) || is_internal_port(mon->pid));
 	if (is_internal_port(mon->pid)) {
@@ -11623,6 +11641,12 @@ static void doit_exit_monitor(ErtsMonitor *mon, void *vpcontext)
 		}
 	    }
 	}
+	break;
+    case MON_TIME_OFFSET:
+	erts_demonitor_time_offset(mon->ref);
+	break;
+    default:
+	ERTS_INTERNAL_ERROR("Invalid monitor type");
     }
  done:
     /* As the monitors are previously removed from the process, 
diff --git a/erts/emulator/beam/erl_process.h b/erts/emulator/beam/erl_process.h
index f50b217d4a..6ef56b1974 100644
--- a/erts/emulator/beam/erl_process.h
+++ b/erts/emulator/beam/erl_process.h
@@ -341,7 +341,7 @@ typedef struct {
 } ErtsRunQueueInfo;
 
 
-#ifdef HAVE_GETHRTIME
+#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
 #  undef ERTS_HAVE_SCHED_UTIL_BALANCING_SUPPORT_OPT
 #  define ERTS_HAVE_SCHED_UTIL_BALANCING_SUPPORT_OPT 1
 #endif
@@ -588,6 +588,10 @@ struct ErtsSchedulerData_ {
     ErtsAuxWorkData aux_work_data;
     ErtsAtomCacheMap atom_cache_map;
 
+    Uint32 thr_id;
+    Uint64 unique;
+    Uint64 ref;
+
     ErtsSchedAllocData alloc_data;
 
     Uint64 reductions;
diff --git a/erts/emulator/beam/erl_thr_progress.c b/erts/emulator/beam/erl_thr_progress.c
index 664c479eb6..f111846041 100644
--- a/erts/emulator/beam/erl_thr_progress.c
+++ b/erts/emulator/beam/erl_thr_progress.c
@@ -1342,18 +1342,16 @@ erts_thr_progress_fatal_error_block(SWord timeout,
     ErtsThrPrgrData *tpd = perhaps_thr_prgr_data(NULL);
     erts_aint32_t bc;
     SWord time_left = timeout;
-    SysTimeval to;
+    ErtsMonotonicTime timeout_time;
 
     /*
      * Counting poll intervals may give us a too long timeout
-     * if cpu is busy. If we got tolerant time of day we use it
-     * to prevent this.
+     * if cpu is busy. We use timeout time to try to prevent
+     * this. In case we havn't got time correction this may
+     * however fail too...
      */
-    if (!erts_disable_tolerant_timeofday) {
-	erts_get_timeval(&to);
-	to.tv_sec += timeout / 1000;
-	to.tv_sec += timeout % 1000;
-    }
+    timeout_time = erts_get_monotonic_time();
+    timeout_time += ERTS_MSEC_TO_MONOTONIC((ErtsMonotonicTime) timeout);
 
     if (!tpd) {
 	/*
@@ -1378,14 +1376,8 @@ erts_thr_progress_fatal_error_block(SWord timeout,
 	    break; /* Succefully blocked all managed threads */
 	if (time_left <= 0)
 	    break; /* Timeout */
-	if (!erts_disable_tolerant_timeofday) {
-	    SysTimeval now;
-	    erts_get_timeval(&now);
-	    if (now.tv_sec > to.tv_sec)
-		break; /* Timeout */
-	    if (now.tv_sec == to.tv_sec && now.tv_usec >= to.tv_usec)
-		break; /* Timeout */
-	}
+	if (timeout_time <= erts_get_monotonic_time())
+	    break; /* Timeout */
     }
 }
 
diff --git a/erts/emulator/beam/erl_time.h b/erts/emulator/beam/erl_time.h
index 4bbdcaa3e3..e461594e9c 100644
--- a/erts/emulator/beam/erl_time.h
+++ b/erts/emulator/beam/erl_time.h
@@ -20,11 +20,12 @@
 #ifndef ERL_TIME_H__
 #define ERL_TIME_H__
 
-#define ERTS_SHORT_TIME_T_MAX ERTS_AINT32_T_MAX
-#define ERTS_SHORT_TIME_T_MIN ERTS_AINT32_T_MIN
-typedef erts_aint32_t erts_short_time_t;
+#if defined(DEBUG) || 0
+#define ERTS_TIME_ASSERT(B) ERTS_ASSERT(B)
+#else
+#define ERTS_TIME_ASSERT(B) ((void) 1)
+#endif
 
-extern erts_smp_atomic32_t do_time;	/* set at clock interrupt */
 extern SysTimeval erts_first_emu_time;
 
 /*
@@ -34,7 +35,7 @@ typedef struct erl_timer {
     struct erl_timer* next;	/* next entry tiw slot or chain */
     struct erl_timer* prev;	/* prev entry tiw slot or chain */
     Uint slot;			/* slot in timer wheel */
-    Uint count;			/* number of loops remaining */
+    ErtsMonotonicTime timeout_pos; /* Timeout in absolute clock ticks */
     int    active;		/* 1=activated, 0=deactivated */
     /* called when timeout */
     void (*timeout)(void*);
@@ -70,36 +71,36 @@ void erts_create_smp_ptimer(ErtsSmpPTimer **timer_ref,
 void erts_cancel_smp_ptimer(ErtsSmpPTimer *ptimer);
 #endif
 
+void erts_monitor_time_offset(Eterm id, Eterm ref);
+int erts_demonitor_time_offset(Eterm ref);
+
+void erts_early_init_time_sup(void);
+void erts_late_init_time_sup(void);
+
 /* timer-wheel api */
 
-void erts_init_time(void);
+void erts_init_time(int time_correction, ErtsTimeWarpMode time_warp_mode);
 void erts_set_timer(ErlTimer*, ErlTimeoutProc, ErlCancelProc, void*, Uint);
 void erts_cancel_timer(ErlTimer*);
-void erts_bump_timer(erts_short_time_t);
+void erts_bump_timers(ErtsMonotonicTime);
 Uint erts_timer_wheel_memory_size(void);
 Uint erts_time_left(ErlTimer *);
-erts_short_time_t erts_next_time(void);
 
 #ifdef DEBUG
 void erts_p_slpq(void);
 #endif
 
-ERTS_GLB_INLINE erts_short_time_t erts_do_time_read_and_reset(void);
-ERTS_GLB_INLINE void erts_do_time_add(erts_short_time_t);
+ErtsMonotonicTime erts_check_next_timeout_time(ErtsMonotonicTime);
 
-#if ERTS_GLB_INLINE_INCL_FUNC_DEF
+extern erts_atomic64_t erts_next_timeout__;
 
-ERTS_GLB_INLINE erts_short_time_t erts_do_time_read_and_reset(void)
-{
-    erts_short_time_t time = erts_smp_atomic32_xchg_acqb(&do_time, 0);
-    if (time < 0)
-	erl_exit(ERTS_ABORT_EXIT, "Internal time management error\n");
-    return time;
-}
+ERTS_GLB_INLINE ErtsMonotonicTime erts_next_timeout_time(void);
+
+#if ERTS_GLB_INLINE_INCL_FUNC_DEF
 
-ERTS_GLB_INLINE void erts_do_time_add(erts_short_time_t elapsed)
+ERTS_GLB_INLINE ErtsMonotonicTime erts_next_timeout_time(void)
 {
-    erts_smp_atomic32_add_relb(&do_time, elapsed);
+    return (ErtsMonotonicTime) erts_atomic64_read_acqb(&erts_next_timeout__);
 }
 
 #endif /* #if ERTS_GLB_INLINE_INCL_FUNC_DEF */
@@ -121,25 +122,228 @@ void erts_get_now_cpu(Uint* megasec, Uint* sec, Uint* microsec);
 typedef UWord erts_approx_time_t;
 erts_approx_time_t erts_get_approx_time(void);
 
-void erts_get_timeval(SysTimeval *tv);
-erts_time_t erts_get_time(void);
+int erts_has_time_correction(void);
+int erts_check_time_adj_support(int time_correction,
+				ErtsTimeWarpMode time_warp_mode);
+
+ErtsTimeWarpMode erts_time_warp_mode(void);
+
+typedef enum {
+    ERTS_TIME_OFFSET_PRELIMINARY,
+    ERTS_TIME_OFFSET_FINAL,
+    ERTS_TIME_OFFSET_VOLATILE
+} ErtsTimeOffsetState;
+
+ErtsTimeOffsetState erts_time_offset_state(void); 
+ErtsTimeOffsetState erts_finalize_time_offset(void); 
+struct process;
+Eterm erts_get_monotonic_start_time(struct process *c_p);
+Eterm erts_monotonic_time_source(struct process*c_p);
+
+#ifdef SYS_CLOCK_RESOLUTION
+#define ERTS_CLKTCK_RESOLUTION ((ErtsMonotonicTime) (SYS_CLOCK_RESOLUTION*1000))
+#else
+#define ERTS_CLKTCK_RESOLUTION (erts_time_sup__.r.o.clktck_resolution)
+#endif
+
+struct erts_time_sup_read_only__ {
+    ErtsMonotonicTime monotonic_time_unit;
+#ifndef SYS_CLOCK_RESOLUTION
+    ErtsMonotonicTime clktck_resolution;
+#endif
+};
+
+typedef struct {
+    union {
+	struct erts_time_sup_read_only__ o;
+	char align__[(((sizeof(struct erts_time_sup_read_only__) - 1)
+		       / ASSUMED_CACHE_LINE_SIZE) + 1)
+		     * ASSUMED_CACHE_LINE_SIZE];
+    } r;
+} ErtsTimeSupData;
+
+extern ErtsTimeSupData erts_time_sup__;
 
-ERTS_GLB_INLINE int erts_cmp_timeval(SysTimeval *t1p, SysTimeval *t2p);
+ERTS_GLB_INLINE Uint64
+erts_time_unit_conversion(Uint64 value,
+			  Uint32 from_time_unit,
+			  Uint32 to_time_unit);
 
 #if ERTS_GLB_INLINE_INCL_FUNC_DEF
 
-ERTS_GLB_INLINE int
-erts_cmp_timeval(SysTimeval *t1p, SysTimeval *t2p)
+ERTS_GLB_INLINE Uint64
+erts_time_unit_conversion(Uint64 value,
+			  Uint32 from_time_unit,
+			  Uint32 to_time_unit)
 {
-    if (t1p->tv_sec == t2p->tv_sec) {
-	if (t1p->tv_usec < t2p->tv_usec)
-	    return -1;
-	else if (t1p->tv_usec > t2p->tv_usec)
-	    return 1;
-	return 0;
-    }
-    return t1p->tv_sec < t2p->tv_sec ? -1 : 1;
+    Uint64 high, low, result;
+    if (value <= ~((Uint64) 0)/to_time_unit)
+	return (value*to_time_unit)/from_time_unit;
+
+    low = value & ((Uint64) 0xffffffff);
+    high = (value >> 32) & ((Uint64) 0xffffffff);
+
+    low *= to_time_unit;
+    high *= to_time_unit;
+
+    high += (low >> 32) & ((Uint64) 0xffffffff);
+    low &= ((Uint64) 0xffffffff);
+
+    result = high % from_time_unit;
+    high /= from_time_unit;
+    high <<= 32;
+
+    result <<= 32;
+    result += low;
+    result /= from_time_unit;
+    result += high;
+
+    return result;
 }
 
-#endif /* #if ERTS_GLB_INLINE_INCL_FUNC_DEF */
+#endif /* ERTS_GLB_INLINE_INCL_FUNC_DEF */
+
+#if ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT
+
+/*
+ * If the monotonic time unit is a compile time constant,
+ * it is assumed (and need) to be a power of 10.
+ */
+
+#define ERTS_MONOTONIC_TIME_UNIT \
+    ((ErtsMonotonicTime) ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT)
+
+#if ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT == 1000*1000*1000
+/* Nano-second time unit */
+
+#define ERTS_MONOTONIC_TO_SEC__(NSEC) ((NSEC) / (1000*1000*1000))
+#define ERTS_MONOTONIC_TO_MSEC__(NSEC) ((NSEC) / (1000*1000))
+#define ERTS_MONOTONIC_TO_USEC__(NSEC) ((NSEC) / 1000)
+#define ERTS_MONOTONIC_TO_NSEC__(NSEC) (NSEC)
+
+#define ERTS_SEC_TO_MONOTONIC__(SEC) (((ErtsMonotonicTime) (SEC))*(1000*1000*1000))
+#define ERTS_MSEC_TO_MONOTONIC__(MSEC) (((ErtsMonotonicTime) (MSEC))*(1000*1000))
+#define ERTS_USEC_TO_MONOTONIC__(USEC) (((ErtsMonotonicTime) (USEC))*1000)
+#define ERTS_NSEC_TO_MONOTONIC__(NSEC) ((ErtsMonotonicTime) (NSEC))
+
+#elif ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT == 1000*1000
+/* Micro-second time unit */
+
+#define ERTS_MONOTONIC_TO_SEC__(USEC) ((USEC) / (1000*1000))
+#define ERTS_MONOTONIC_TO_MSEC__(USEC) ((USEC) / 1000)
+#define ERTS_MONOTONIC_TO_USEC__(USEC) (USEC)
+#define ERTS_MONOTONIC_TO_NSEC__(USEC) ((USEC)*1000)
+
+#define ERTS_SEC_TO_MONOTONIC__(SEC) (((ErtsMonotonicTime) (SEC))*(1000*1000))
+#define ERTS_MSEC_TO_MONOTONIC__(MSEC) (((ErtsMonotonicTime) (MSEC))*1000)
+#define ERTS_USEC_TO_MONOTONIC__(USEC) ((ErtsMonotonicTime) (USEC))
+#define ERTS_NSEC_TO_MONOTONIC__(NSEC) (((ErtsMonotonicTime) (NSEC))/1000)
+
+#elif ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT == 1000
+/* Milli-second time unit */
+
+#define ERTS_MONOTONIC_TO_SEC__(MSEC) ((USEC)/(1000))
+#define ERTS_MONOTONIC_TO_MSEC__(MSEC) (MSEC)
+#define ERTS_MONOTONIC_TO_USEC__(MSEC) ((MSEC)*1000)
+#define ERTS_MONOTONIC_TO_NSEC__(MSEC) ((MSEC)*(1000*1000))
+
+#define ERTS_SEC_TO_MONOTONIC__(SEC) (((ErtsMonotonicTime) (SEC))*1000)
+#define ERTS_MSEC_TO_MONOTONIC__(MSEC) ((ErtsMonotonicTime) (MSEC))
+#define ERTS_USEC_TO_MONOTONIC__(USEC) (((ErtsMonotonicTime) (USEC))/1000)
+#define ERTS_NSEC_TO_MONOTONIC__(NSEC) (((ErtsMonotonicTime) (NSEC))/(1000*1000))
+
+#else
+#error Missing implementation for monotonic time unit
+#endif
+
+#define ERTS_MONOTONIC_TO_CLKTCKS__(MON) \
+    ((MON) / (ERTS_MONOTONIC_TIME_UNIT/ERTS_CLKTCK_RESOLUTION))
+#define ERTS_CLKTCKS_TO_MONOTONIC__(TCKS) \
+    ((TCKS) * (ERTS_MONOTONIC_TIME_UNIT/ERTS_CLKTCK_RESOLUTION))
+
+#else /* !ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT */
+
+#define ERTS_MONOTONIC_TIME_UNIT (erts_time_sup__.r.o.monotonic_time_unit)
+
+#define ERTS_CONV_FROM_MON_UNIT___(M, TO)				\
+    ((ErtsMonotonicTime)						\
+     erts_time_unit_conversion((Uint64) (M),				\
+			       (Uint32) ERTS_MONOTONIC_TIME_UNIT,	\
+			       (Uint32) (TO)))
+
+#define ERTS_CONV_TO_MON_UNIT___(M, FROM)				\
+    ((ErtsMonotonicTime)						\
+     erts_time_unit_conversion((Uint64) (M),				\
+			       (Uint32) (FROM),				\
+			       (Uint32) ERTS_MONOTONIC_TIME_UNIT))	\
+
+#define ERTS_MONOTONIC_TO_SEC__(M) \
+    ERTS_CONV_FROM_MON_UNIT___((M), 1)
+#define ERTS_MONOTONIC_TO_MSEC__(M) \
+    ERTS_CONV_FROM_MON_UNIT___((M), 1000)
+#define ERTS_MONOTONIC_TO_USEC__(M) \
+    ERTS_CONV_FROM_MON_UNIT___((M), 1000*1000)
+#define ERTS_MONOTONIC_TO_NSEC__(M) \
+    ERTS_CONV_FROM_MON_UNIT___((M), 1000*1000*1000)
+
+#define ERTS_SEC_TO_MONOTONIC__(SEC) \
+    ERTS_CONV_TO_MON_UNIT___((SEC), 1)
+#define ERTS_MSEC_TO_MONOTONIC__(MSEC) \
+    ERTS_CONV_TO_MON_UNIT___((MSEC), 1000)
+#define ERTS_USEC_TO_MONOTONIC__(USEC) \
+    ERTS_CONV_TO_MON_UNIT___((USEC), 1000*1000)
+#define ERTS_NSEC_TO_MONOTONIC__(NSEC) \
+    ERTS_CONV_TO_MON_UNIT___((NSEC), 1000*1000*1000)
+
+#define ERTS_MONOTONIC_TO_CLKTCKS__(MON) \
+    ERTS_CONV_FROM_MON_UNIT___((MON), ERTS_CLKTCK_RESOLUTION)
+#define ERTS_CLKTCKS_TO_MONOTONIC__(TCKS) \
+    ERTS_CONV_TO_MON_UNIT___((TCKS), ERTS_CLKTCK_RESOLUTION)
+
+#endif /* !ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT */
+
+#define ERTS_MSEC_TO_CLKTCKS__(MON) \
+    ((MON) * (ERTS_CLKTCK_RESOLUTION/1000))
+#define ERTS_CLKTCKS_TO_MSEC__(TCKS) \
+    ((TCKS) / (ERTS_CLKTCK_RESOLUTION/1000))
+
+#define ERTS_MONOTONIC_TO_SEC(X)	\
+    (ERTS_TIME_ASSERT((X) >= 0),	\
+     ERTS_MONOTONIC_TO_SEC__((X)))
+#define ERTS_MONOTONIC_TO_MSEC(X)	\
+    (ERTS_TIME_ASSERT((X) >= 0),	\
+     ERTS_MONOTONIC_TO_MSEC__((X)))
+#define ERTS_MONOTONIC_TO_USEC(X)	\
+    (ERTS_TIME_ASSERT((X) >= 0),	\
+     ERTS_MONOTONIC_TO_USEC__((X)))
+#define ERTS_MONOTONIC_TO_NSEC(X)	\
+    (ERTS_TIME_ASSERT((X) >= 0),	\
+     ERTS_MONOTONIC_TO_NSEC__((X)))
+#define ERTS_SEC_TO_MONOTONIC(X)	\
+    (ERTS_TIME_ASSERT((X) >= 0),	\
+     ERTS_SEC_TO_MONOTONIC__((X)))
+#define ERTS_MSEC_TO_MONOTONIC(X)	\
+    (ERTS_TIME_ASSERT((X) >= 0),	\
+     ERTS_MSEC_TO_MONOTONIC__((X)))
+#define ERTS_USEC_TO_MONOTONIC(X)	\
+    (ERTS_TIME_ASSERT((X) >= 0),	\
+     ERTS_USEC_TO_MONOTONIC__((X)))
+#define ERTS_NSEC_TO_MONOTONIC(X)	\
+    (ERTS_TIME_ASSERT((X) >= 0),	\
+     ERTS_NSEC_TO_MONOTONIC__((X)))
+
+#define ERTS_MONOTONIC_TO_CLKTCKS(X) \
+    (ERTS_TIME_ASSERT((X) >= 0),		\
+     ERTS_MONOTONIC_TO_CLKTCKS__((X)))
+#define ERTS_CLKTCKS_TO_MONOTONIC(X) \
+    (ERTS_TIME_ASSERT((X) >= 0),		\
+     ERTS_CLKTCKS_TO_MONOTONIC__((X)))
+
+#define ERTS_MSEC_TO_CLKTCKS(X) \
+    (ERTS_TIME_ASSERT((X) >= 0),		\
+     ERTS_MSEC_TO_CLKTCKS__((X)))
+#define ERTS_CLKTCKS_TO_MSEC(X) \
+    (ERTS_TIME_ASSERT((X) >= 0),		\
+     ERTS_CLKTCKS_TO_MSEC__((X)))
+
 #endif /* ERL_TIME_H__ */
diff --git a/erts/emulator/beam/erl_time_sup.c b/erts/emulator/beam/erl_time_sup.c
index 3272a5326d..1534fb8058 100644
--- a/erts/emulator/beam/erl_time_sup.c
+++ b/erts/emulator/beam/erl_time_sup.c
@@ -18,60 +18,8 @@
  */
 
 /*
-** Support routines for the timer wheel
-**
-** This code contains two strategies for dealing with 
-** date/time changes in the system. 
-** If the system has some kind of high resolution timer (HAVE_GETHRTIME),
-** the high resolution timer is used to correct the time-of-day and the
-** timeouts, the base source is the hrtimer, but at certain intervals the 
-** OS time-of-day is checked and if it is not within certain bounds, the 
-** delivered time gets slowly adjusted for each call until
-** it corresponds to the system time (built-in adjtime...). 
-** The call gethrtime() is detected by autoconf on Unix, but other 
-** platforms may define it in erl_*_sys.h and implement 
-** their own high resolution timer. The high resolution timer
-** strategy is (probably) best on all systems where the timer have 
-** a resolution higher or equal to gettimeofday (or what's implemented
-** is sys_gettimeofday()). The actual resolution is the interesting thing,
-** not the unit's thats used (i.e. on VxWorks, nanoseconds can be
-** retrieved in terms of units, but the actual resolution is the same as 
-** for the clock ticks).
-** If the systems best timer routine is kernel ticks returned from 
-** sys_times(), and the actual resolution of sys_gettimeofday() is
-** better (like most unixes that does not have any realtime extensions), 
-** another strategy is used. The tolerant gettimeofday() corrects 
-** the value with respect to uptime (sys_times() return value) and checks 
-** for correction both when delivering timeticks and delivering nowtime.
-** this strategy is slower, but accurate on systems without better timer 
-** routines. The kernel tick resolution is not enough to implement
-** a gethrtime routine. On Linux and other non solaris unix-boxes the second 
-** strategy is used, on all other platforms we use the first.
-** 
-** The following is expected (from sys.[ch] and erl_*_sys.h):
-**
-** 64 bit integers. So it is, and so it will be.
-**
-** sys_init_time(), will return the clock resolution in MS and
-** that's about it. More could be added of course
-** If the clock-rate is constant (i.e. 1 ms) one can define 
-** SYS_CLOCK_RESOLUTION (to 1),
-** which makes erts_deliver_time/erts_time_remaining a bit faster.
-**
-** if HAVE_GETHRTIME is defined:
-**    sys_gethrtime() will return a SysHrTime (long long) representing 
-**    nanoseconds, sys_init_hrtime() will do any initialization.
-** else
-**    a long (64bit) integer type called Sint64 should be defined.
-**
-** sys_times() will return clock_ticks since start and 
-**    fill in a SysTimes structure (struct tms). Instead of CLK_TCK, 
-**    SYS_CLK_TCK is used to determine the resolution of kernel ticks.
-**
-** sys_gettimeofday() will take a SysTimeval (a struct timeval) as parameter
-**    and fill it in as gettimeofday(X,NULL).
-**
-*/
+ * Support routines for the time
+ */
 
 #ifdef HAVE_CONFIG_H
 #  include "config.h"
@@ -80,384 +28,1028 @@
 #include "sys.h"
 #include "erl_vm.h"
 #include "global.h"
-
+ 
 static erts_smp_mtx_t erts_timeofday_mtx;
-
-static SysTimeval inittv; /* Used everywhere, the initial time-of-day */
+static erts_smp_mtx_t erts_get_time_mtx;
 
 static SysTimes t_start; /* Used in elapsed_time_both */
-static SysTimeval gtv; /* Used in wall_clock_elapsed_time_both */
-static SysTimeval then; /* Used in get_now */
-static SysTimeval last_emu_time; /* Used in erts_get_emu_time() */
-SysTimeval erts_first_emu_time; /* Used in erts_get_emu_time() */
+static ErtsMonotonicTime prev_wall_clock_elapsed; /* Used in wall_clock_elapsed_time_both */
+static ErtsMonotonicTime previous_now; /* Used in get_now */
+
+static ErtsMonitor *time_offset_monitors = NULL;
+static Uint no_time_offset_monitors = 0;
 
-union {
-    erts_smp_atomic_t time;
-    char align[ERTS_CACHE_LINE_SIZE];
-} approx erts_align_attribute(ERTS_CACHE_LINE_SIZE);
+#ifdef DEBUG
+static int time_sup_initialized = 0;
+#endif
+
+#define ERTS_MONOTONIC_TIME_KILO \
+    ((ErtsMonotonicTime) 1000)
+#define ERTS_MONOTONIC_TIME_MEGA \
+    (ERTS_MONOTONIC_TIME_KILO*ERTS_MONOTONIC_TIME_KILO)
+#define ERTS_MONOTONIC_TIME_GIGA \
+    (ERTS_MONOTONIC_TIME_MEGA*ERTS_MONOTONIC_TIME_KILO)
+#define ERTS_MONOTONIC_TIME_TERA \
+    (ERTS_MONOTONIC_TIME_GIGA*ERTS_MONOTONIC_TIME_KILO)
 
 static void
-init_approx_time(void)
+schedule_send_time_offset_changed_notifications(ErtsMonotonicTime new_offset);
+
+/*
+ * NOTE! ERTS_MONOTONIC_TIME_START *need* to be a multiple
+ *       of ERTS_MONOTONIC_TIME_UNIT.
+ */
+
+#if ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT
+
+#ifdef ARCH_32
+/*
+ * Want to use a big-num of arity 2 as long as possible (584 years
+ * in the nano-second time unit case).
+ */
+#define ERTS_MONOTONIC_TIME_START		\
+    (((((((ErtsMonotonicTime) 1) << 32)-1)	\
+       / ERTS_MONOTONIC_TIME_UNIT)		\
+      * ERTS_MONOTONIC_TIME_UNIT)		\
+     + ERTS_MONOTONIC_TIME_UNIT)
+
+#else /* ARCH_64 */
+
+#if ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT <= 1000*1000
+
+/*
+ * Using micro second time unit or lower. Start at zero since
+ * time will remain an immediate for a very long time anyway
+ * (18279 years in the micro second case)...
+ */
+#define ERTS_MONOTONIC_TIME_START ((ErtsMonotonicTime) 0)
+
+#else /* ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT > 1000*1000 */
+
+/*
+ * Want to use an immediate as long as possible (36 years in the
+ * nano-second time unit case).
+*/
+#define ERTS_MONOTONIC_TIME_START 		\
+    ((((ErtsMonotonicTime) MIN_SMALL)		\
+      / ERTS_MONOTONIC_TIME_UNIT)		\
+     * ERTS_MONOTONIC_TIME_UNIT)
+
+#endif /* ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT > 1000*1000 */
+
+#endif /* ARCH_64 */
+
+#define ERTS_MONOTONIC_OFFSET_NATIVE ERTS_MONOTONIC_TIME_START
+#define ERTS_MONOTONIC_OFFSET_NSEC ERTS_MONOTONIC_TO_NSEC__(ERTS_MONOTONIC_TIME_START)
+#define ERTS_MONOTONIC_OFFSET_USEC ERTS_MONOTONIC_TO_USEC__(ERTS_MONOTONIC_TIME_START)
+#define ERTS_MONOTONIC_OFFSET_MSEC ERTS_MONOTONIC_TO_MSEC__(ERTS_MONOTONIC_TIME_START)
+#define ERTS_MONOTONIC_OFFSET_SEC ERTS_MONOTONIC_TO_SEC__(ERTS_MONOTONIC_TIME_START)
+
+#else /* ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT */
+
+/*
+ * Initialized in erts_init_time_sup()...
+ */
+
+#define ERTS_MONOTONIC_TIME_START (time_sup.r.o.start)
+#define ERTS_MONOTONIC_OFFSET_NATIVE (time_sup.r.o.start_offset.native)
+#define ERTS_MONOTONIC_OFFSET_NSEC (time_sup.r.o.start_offset.nsec)
+#define ERTS_MONOTONIC_OFFSET_USEC (time_sup.r.o.start_offset.usec)
+#define ERTS_MONOTONIC_OFFSET_MSEC (time_sup.r.o.start_offset.msec)
+#define ERTS_MONOTONIC_OFFSET_SEC (time_sup.r.o.start_offset.sec)
+
+#endif /* ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT */
+
+#define ERTS_MONOTONIC_TO_SYS_TIME_VAL(TVP, MT)				\
+    do {								\
+	ErtsMonotonicTime sec__, usec__;				\
+	sec__ = ERTS_MONOTONIC_TO_SEC((MT));				\
+	usec__ = ERTS_MONOTONIC_TO_USEC((MT)) - sec__*1000000;		\
+	ASSERT(usec__ < 1000000);					\
+	(TVP)->tv_sec = sec__;						\
+	(TVP)->tv_usec = usec__;					\
+    } while (0)
+
+#define ERTS_MAX_SYSTEM_TIME_DIFF ERTS_MSEC_TO_MONOTONIC(10)
+#define ERTS_SYSTEM_TIME_DIFF_EXCEED_LIMIT(ESYSTIME, OSSYSTIME)		\
+    (((Uint64) (ESYSTIME)) - (((Uint64) (OSSYSTIME))			\
+			      - ERTS_MAX_SYSTEM_TIME_DIFF)		\
+     > 2*ERTS_MAX_SYSTEM_TIME_DIFF)
+
+#define ERTS_TIME_CORRECTION_LARGE_ADJ_DIFF (ERTS_MAX_SYSTEM_TIME_DIFF/2)
+#define ERTS_TIME_CORRECTION_SMALL_ADJ_DIFF ERTS_USEC_TO_MONOTONIC(500)
+
+struct time_sup_read_only__ {
+    ErtsMonotonicTime (*get_time)(void);
+    int correction;
+    ErtsTimeWarpMode warp_mode;
+#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+    ErtsMonotonicTime moffset;
+    int os_monotonic_disable;
+    char *os_monotonic_func;
+    char *os_monotonic_clock_id;
+    int os_monotonic_locked;
+    Uint64 os_monotonic_resolution;
+#endif
+#if !ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT
+    ErtsMonotonicTime start;
+    struct {
+	ErtsMonotonicTime native;
+	ErtsMonotonicTime nsec;
+	ErtsMonotonicTime usec;
+	ErtsMonotonicTime msec;
+	ErtsMonotonicTime sec;
+    } start_offset;
+#endif
+};
+
+typedef struct {
+#ifndef ERTS_HAVE_CORRECTED_OS_MONOTONIC
+    ErtsMonotonicTime drift; /* Correction for os monotonic drift */
+#endif
+    ErtsMonotonicTime error; /* Correction for error between system times */
+} ErtsMonotonicCorrection;
+
+typedef struct {
+    ErtsMonotonicTime erl_mtime;
+    ErtsMonotonicTime os_mtime;
+    ErtsMonotonicCorrection correction;
+} ErtsMonotonicCorrectionInstance;
+
+#define ERTS_DRIFT_INTERVALS 5
+typedef struct {
+    struct {
+	struct {
+	    ErtsMonotonicTime sys;
+	    ErtsMonotonicTime mon;
+	} diff;
+	struct {
+	    ErtsMonotonicTime sys;
+	    ErtsMonotonicTime mon;
+	} time;
+    } intervals[ERTS_DRIFT_INTERVALS];
+    struct {
+	ErtsMonotonicTime sys;
+	ErtsMonotonicTime mon;
+    } acc;
+    int ix;
+    int dirty_counter;
+} ErtsMonotonicDriftData;
+
+typedef struct {
+    ErtsMonotonicCorrectionInstance prev;
+    ErtsMonotonicCorrectionInstance curr;    
+#ifndef ERTS_HAVE_CORRECTED_OS_MONOTONIC
+    ErtsMonotonicDriftData drift;
+#endif
+    ErtsMonotonicTime last_check;
+    int short_check_interval;
+} ErtsMonotonicCorrectionData;
+
+struct time_sup_infrequently_changed__ {
+#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+    struct {
+	erts_smp_rwmtx_t rwmtx;
+	ErlTimer timer;
+	ErtsMonotonicCorrectionData cdata;
+    } parmon;
+    ErtsMonotonicTime minit;
+#endif
+    int finalized_offset;
+    SysTimeval inittv; /* Used everywhere, the initial time-of-day */
+    ErtsMonotonicTime not_corrected_moffset;
+    erts_atomic64_t offset;
+};
+
+struct time_sup_frequently_changed__ {
+    ErtsMonotonicTime last_not_corrected_time;
+};
+
+static struct {
+    union {
+	struct time_sup_read_only__ o;
+	char align__[ERTS_ALC_CACHE_LINE_ALIGN_SIZE(sizeof(struct time_sup_read_only__))];
+    } r;
+    union {
+	struct time_sup_infrequently_changed__ c;
+	char align__[ERTS_ALC_CACHE_LINE_ALIGN_SIZE(sizeof(struct time_sup_infrequently_changed__))];
+    } inf;
+    union {
+	struct time_sup_frequently_changed__ c;
+	char align__[ERTS_ALC_CACHE_LINE_ALIGN_SIZE(sizeof(struct time_sup_frequently_changed__))];
+    } f;
+} time_sup erts_align_attribute(ERTS_CACHE_LINE_SIZE);
+
+ErtsTimeSupData erts_time_sup__ erts_align_attribute(ERTS_CACHE_LINE_SIZE);
+
+/*
+ * erts_get_approx_time() returns an *approximate* time
+ * in seconds. NOTE that this time may jump backwards!!!
+ */
+erts_approx_time_t
+erts_get_approx_time(void)
 {
-    erts_smp_atomic_init_nob(&approx.time, 0);
+    SysTimeval tv;
+    sys_gettimeofday(&tv);
+
+    return (erts_approx_time_t) tv.tv_sec;
 }
 
-static ERTS_INLINE erts_approx_time_t
-get_approx_time(void)
+static ERTS_INLINE void
+init_time_offset(ErtsMonotonicTime offset)
 {
-    return (erts_approx_time_t) erts_smp_atomic_read_nob(&approx.time);
+    erts_atomic64_init_nob(&time_sup.inf.c.offset, (erts_aint64_t) offset);
 }
 
 static ERTS_INLINE void
-update_approx_time(SysTimeval *tv)
+set_time_offset(ErtsMonotonicTime offset)
 {
-    erts_approx_time_t new_secs = (erts_approx_time_t) tv->tv_sec;
-    erts_approx_time_t old_secs = get_approx_time();
-    if (old_secs != new_secs)
-	erts_smp_atomic_set_nob(&approx.time, new_secs);
+    erts_atomic64_set_relb(&time_sup.inf.c.offset, (erts_aint64_t) offset);
 }
 
-/*
- * erts_get_approx_time() returns an *approximate* time
- * in seconds. NOTE that this time may jump backwards!!!
- */
-erts_approx_time_t
-erts_get_approx_time(void)
+static ERTS_INLINE ErtsMonotonicTime
+get_time_offset(void)
 {
-    return get_approx_time();
+    return (ErtsMonotonicTime) erts_atomic64_read_acqb(&time_sup.inf.c.offset);
 }
 
-#ifdef HAVE_GETHRTIME
 
-int erts_disable_tolerant_timeofday;
+#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+
+/*
+ * Time correction adjustments made due to
+ * error between Erlang system time and OS
+ * system time:
+ * - Large adjustment ~1%
+ * - Small adjustment ~0.05%
+ */
+#define ERTS_TCORR_ERR_UNIT 2048
+#define ERTS_TCORR_ERR_LARGE_ADJ 20
+#define ERTS_TCORR_ERR_SMALL_ADJ 1
 
-static SysHrTime hr_init_time, hr_last_correction_check, 
-    hr_correction, hr_last_time;
+#define ERTS_INIT_SHORT_INTERVAL_COUNTER 10
+#define ERTS_LONG_TIME_CORRECTION_CHECK ERTS_SEC_TO_MONOTONIC(60)
+#define ERTS_SHORT_TIME_CORRECTION_CHECK ERTS_SEC_TO_MONOTONIC(15)
 
-static void init_tolerant_timeofday(void)
+#define ERTS_TIME_DRIFT_MAX_ADJ_DIFF ERTS_USEC_TO_MONOTONIC(100)
+#define ERTS_TIME_DRIFT_MIN_ADJ_DIFF ERTS_USEC_TO_MONOTONIC(5)
+
+static ERTS_INLINE ErtsMonotonicTime
+calc_corrected_erl_mtime(ErtsMonotonicTime os_mtime,
+			 ErtsMonotonicCorrectionInstance *cip,
+			 ErtsMonotonicTime *os_mdiff_p)
 {
-    /* Should be in sys.c */
-#if defined(HAVE_SYSCONF) && defined(_SC_NPROCESSORS_CONF)
-    if (sysconf(_SC_NPROCESSORS_CONF) > 1) {
-	char b[1024];
-	int maj,min,build;
-	os_flavor(b,1024);
-	os_version(&maj,&min,&build);
-	if (!strcmp(b,"sunos") && maj <= 5 && min <= 7) {
-	    erts_disable_tolerant_timeofday = 1;
-	}
-    }
+    ErtsMonotonicTime erl_mtime, diff = os_mtime - cip->os_mtime;
+    ERTS_TIME_ASSERT(diff >= 0);
+#ifndef ERTS_HAVE_CORRECTED_OS_MONOTONIC
+    diff += (cip->correction.drift*diff)/ERTS_MONOTONIC_TIME_UNIT;
 #endif
-    hr_init_time = sys_gethrtime();
-    hr_last_correction_check = hr_last_time = hr_init_time;
-    hr_correction = 0;
+    erl_mtime = cip->erl_mtime;
+    erl_mtime += diff;
+    erl_mtime += cip->correction.error*(diff/ERTS_TCORR_ERR_UNIT);
+    if (os_mdiff_p)
+	*os_mdiff_p = diff;
+    return erl_mtime;
 }
 
-static void get_tolerant_timeofday(SysTimeval *tv)
+static ErtsMonotonicTime get_corrected_time(void)
 {
-    SysHrTime diff_time, curr;
+    ErtsMonotonicTime os_mtime;
+    ErtsMonotonicCorrectionData cdata;
+    ErtsMonotonicCorrectionInstance *cip;
+
+    erts_smp_rwmtx_rlock(&time_sup.inf.c.parmon.rwmtx);
+
+    os_mtime = erts_os_monotonic_time();
+
+    cdata = time_sup.inf.c.parmon.cdata;
 
-    if (erts_disable_tolerant_timeofday) {
-	sys_gettimeofday(tv);
-	return;
+    erts_smp_rwmtx_runlock(&time_sup.inf.c.parmon.rwmtx);
+
+    if (os_mtime >= cdata.curr.os_mtime)
+	cip = &cdata.curr;
+    else {
+	if (os_mtime < cdata.prev.os_mtime)
+	    erl_exit(ERTS_ABORT_EXIT,
+		     "OS monotonic time stepped backwards\n");
+	cip = &cdata.prev;
     }
-    *tv = inittv;
-    diff_time = ((curr = sys_gethrtime()) + hr_correction - hr_init_time) / 1000; 
 
-    if (curr < hr_init_time) {
-	erl_exit(1,"Unexpected behaviour from operating system high "
-		 "resolution timer");
+    return calc_corrected_erl_mtime(os_mtime, cip, NULL);
+}
+
+static void
+check_time_correction(void *unused)
+{
+    ErtsMonotonicCorrectionData cdata;
+    ErtsMonotonicCorrection new_correction;
+    ErtsMonotonicCorrectionInstance *cip;
+    ErtsMonotonicTime mdiff, sdiff, os_mtime, erl_mtime, os_stime, erl_stime, time_offset;
+    Uint timeout;
+    SysTimeval tod;
+    int set_new_correction, begin_short_intervals = 0;
+
+    erts_smp_rwmtx_rlock(&time_sup.inf.c.parmon.rwmtx);
+
+    ASSERT(time_sup.inf.c.finalized_offset);
+
+    os_mtime = erts_os_monotonic_time();
+    sys_gettimeofday(&tod);
+
+    cdata = time_sup.inf.c.parmon.cdata;
+
+    erts_smp_rwmtx_runlock(&time_sup.inf.c.parmon.rwmtx);
+
+    if (os_mtime < cdata.curr.os_mtime)
+	erl_exit(ERTS_ABORT_EXIT,
+		 "OS monotonic time stepped backwards\n");
+    cip = &cdata.curr;
+
+    erl_mtime = calc_corrected_erl_mtime(os_mtime, cip, &mdiff);
+    time_offset = get_time_offset();
+    erl_stime = erl_mtime + time_offset;
+
+    os_stime = ERTS_SEC_TO_MONOTONIC(tod.tv_sec);
+    os_stime += ERTS_USEC_TO_MONOTONIC(tod.tv_usec);
+
+    sdiff = erl_stime - os_stime;
+
+    new_correction = cip->correction;
+    
+    if (time_sup.r.o.warp_mode == ERTS_MULTI_TIME_WARP_MODE
+	&& (sdiff < -2*ERTS_TIME_CORRECTION_SMALL_ADJ_DIFF
+	    || 2*ERTS_TIME_CORRECTION_SMALL_ADJ_DIFF < sdiff)) {
+	/* System time diff exeeded limits; change time offset... */
+	time_offset -= sdiff;
+	sdiff = 0;
+	set_time_offset(time_offset);
+	schedule_send_time_offset_changed_notifications(time_offset);
+	begin_short_intervals = 1;
+	if (cdata.curr.correction.error == 0)
+	    set_new_correction = 0;
+	else {
+	    set_new_correction = 1;
+	    new_correction.error = 0;
+	}
+    }
+    else if (cdata.curr.correction.error == 0) {
+	if (sdiff < -ERTS_TIME_CORRECTION_SMALL_ADJ_DIFF) {
+	    set_new_correction = 1;
+	    if (sdiff < -ERTS_TIME_CORRECTION_LARGE_ADJ_DIFF)
+		new_correction.error = ERTS_TCORR_ERR_LARGE_ADJ;
+	    else
+		new_correction.error = ERTS_TCORR_ERR_SMALL_ADJ;
+	}
+	else if (sdiff > ERTS_TIME_CORRECTION_SMALL_ADJ_DIFF) {
+	    set_new_correction = 1;
+	    if (sdiff > ERTS_TIME_CORRECTION_LARGE_ADJ_DIFF)
+		new_correction.error = -ERTS_TCORR_ERR_LARGE_ADJ;
+	    else
+		new_correction.error = -ERTS_TCORR_ERR_SMALL_ADJ;
+	}
+	else {
+	    set_new_correction = 0;
+	}
+    }
+    else if (cdata.curr.correction.error > 0) {
+	if (sdiff < 0) {
+	    if (cdata.curr.correction.error == ERTS_TCORR_ERR_LARGE_ADJ
+		|| -ERTS_TIME_CORRECTION_LARGE_ADJ_DIFF <= sdiff)
+		set_new_correction = 0;
+	    else {
+		new_correction.error = ERTS_TCORR_ERR_LARGE_ADJ;
+		set_new_correction = 1;
+	    }
+	}
+	else if (sdiff > ERTS_TIME_CORRECTION_SMALL_ADJ_DIFF) {
+	    set_new_correction = 1;
+	    if (sdiff > ERTS_TIME_CORRECTION_LARGE_ADJ_DIFF)
+		new_correction.error = -ERTS_TCORR_ERR_LARGE_ADJ;
+	    else
+		new_correction.error = -ERTS_TCORR_ERR_SMALL_ADJ;
+	}
+	else {
+	    set_new_correction = 1;
+	    new_correction.error = 0;
+	}
+    }
+    else /* if (cdata.curr.correction.error < 0) */ { 
+	if (0 < sdiff) {
+	    if (cdata.curr.correction.error == -ERTS_TCORR_ERR_LARGE_ADJ
+		|| sdiff <= ERTS_TIME_CORRECTION_LARGE_ADJ_DIFF)
+		set_new_correction = 0;
+	    else {
+		new_correction.error = -ERTS_TCORR_ERR_LARGE_ADJ;
+		set_new_correction = 1;
+	    }
+	    set_new_correction = 0;
+	}
+	else if (sdiff < -ERTS_TIME_CORRECTION_SMALL_ADJ_DIFF) {
+	    set_new_correction = 1;
+	    if (sdiff < -ERTS_TIME_CORRECTION_LARGE_ADJ_DIFF)
+		new_correction.error = ERTS_TCORR_ERR_LARGE_ADJ;
+	    else
+		new_correction.error = ERTS_TCORR_ERR_SMALL_ADJ;
+	}
+	else {
+	    set_new_correction = 1;
+	    new_correction.error = 0;
+	}
     }
 
-    if ((curr - hr_last_correction_check) / 1000 > 1000000) {
-	/* Check the correction need */
-	SysHrTime tv_diff, diffdiff;
-	SysTimeval tmp;
-	int done = 0;
-
-	sys_gettimeofday(&tmp);
-	tv_diff = ((SysHrTime) tmp.tv_sec) * 1000000 + tmp.tv_usec;
-	tv_diff -= ((SysHrTime) inittv.tv_sec) * 1000000 + inittv.tv_usec;
-	diffdiff = diff_time - tv_diff;
-	if (diffdiff > 10000) {
-	    SysHrTime corr = (curr - hr_last_time) / 100;
-	    if (corr / 1000 >= diffdiff) {
-		++done;
-		hr_correction -= ((SysHrTime)diffdiff) * 1000;
-	    } else {
-		hr_correction -= corr;
+#ifndef ERTS_HAVE_CORRECTED_OS_MONOTONIC
+    {
+	ErtsMonotonicDriftData *ddp = &time_sup.inf.c.parmon.cdata.drift;
+	int ix = ddp->ix;
+	ErtsMonotonicTime mtime_diff, old_os_mtime;
+
+	old_os_mtime = ddp->intervals[ix].time.mon;
+	mtime_diff = os_mtime - old_os_mtime;
+
+	if (mtime_diff >= ERTS_SEC_TO_MONOTONIC(10)) {
+	    ErtsMonotonicTime drift_adj, drift_adj_diff, old_os_stime,
+		stime_diff, mtime_acc, stime_acc, avg_drift_adj;
+
+	    old_os_stime = ddp->intervals[ix].time.sys;
+
+	    mtime_acc = ddp->acc.mon;
+	    stime_acc = ddp->acc.sys;
+
+	    avg_drift_adj = ((stime_acc - mtime_acc)*ERTS_MONOTONIC_TIME_UNIT) / mtime_acc;
+
+	    mtime_diff = os_mtime - old_os_mtime;
+	    stime_diff = os_stime - old_os_stime;
+	    drift_adj = ((stime_diff - mtime_diff)*ERTS_MONOTONIC_TIME_UNIT) / mtime_diff;
+	    
+	    ix++;
+	    if (ix >= ERTS_DRIFT_INTERVALS)
+		ix = 0;
+	    mtime_acc -= ddp->intervals[ix].diff.mon;
+	    mtime_acc += mtime_diff;
+	    stime_acc -= ddp->intervals[ix].diff.sys;
+	    stime_acc += stime_diff;
+
+	    ddp->intervals[ix].diff.mon = mtime_diff;
+	    ddp->intervals[ix].diff.sys = stime_diff;
+	    ddp->intervals[ix].time.mon = os_mtime;
+	    ddp->intervals[ix].time.sys = os_stime;
+
+	    ddp->ix = ix;
+	    ddp->acc.mon = mtime_acc;
+	    ddp->acc.sys = stime_acc;
+
+	    /*
+	     * If calculated drift adjustment is if off by more than 20% from the
+	     * average drift we interpret this as a discontinous leap in system
+	     * time and ignore it. If it actually is a change in drift we will
+	     * later detect this when the average drift change.
+	     */
+	    drift_adj_diff = avg_drift_adj - drift_adj;
+	    if (drift_adj_diff < -ERTS_TIME_DRIFT_MAX_ADJ_DIFF
+		|| ERTS_TIME_DRIFT_MAX_ADJ_DIFF < drift_adj_diff) {
+		ddp->dirty_counter = ERTS_DRIFT_INTERVALS;
+		begin_short_intervals = 1;
 	    }
-	    diff_time = (curr + hr_correction - hr_init_time) / 1000; 
-	} else if (diffdiff < -10000) {
-	    SysHrTime corr = (curr - hr_last_time) / 100;
-	    if (corr / 1000 >= -diffdiff) {
-		++done;
-		hr_correction -= ((SysHrTime)diffdiff) * 1000;
-	    } else {
-		hr_correction += corr;
+	    else {
+		if (ddp->dirty_counter <= 0) {
+		    drift_adj = ((stime_acc - mtime_acc)*ERTS_MONOTONIC_TIME_UNIT) / mtime_acc;
+		}
+		if (ddp->dirty_counter >= 0) {
+		    if (ddp->dirty_counter == 0) {
+			/* Force set new drift correction... */
+			set_new_correction = 1;
+		    }
+		    ddp->dirty_counter--;
+		}
+		drift_adj_diff = drift_adj - new_correction.drift;
+		if (drift_adj_diff) {
+		    if (drift_adj_diff > ERTS_TIME_DRIFT_MAX_ADJ_DIFF)
+			drift_adj_diff = ERTS_TIME_DRIFT_MAX_ADJ_DIFF;
+		    else if (drift_adj_diff < -ERTS_TIME_DRIFT_MAX_ADJ_DIFF)
+			drift_adj_diff = -ERTS_TIME_DRIFT_MAX_ADJ_DIFF;
+		    new_correction.drift += drift_adj_diff;
+
+		    if (drift_adj_diff < -ERTS_TIME_DRIFT_MIN_ADJ_DIFF
+			|| ERTS_TIME_DRIFT_MIN_ADJ_DIFF < drift_adj_diff) {
+			set_new_correction = 1;
+		    }
+		}
 	    }
-	    diff_time = (curr + hr_correction - hr_init_time) / 1000; 
-	} else {
-	    ++done;
 	}
-	if (done) {
-	    hr_last_correction_check = curr;
+    }
+#endif
+
+    begin_short_intervals |= set_new_correction;
+    
+    if (begin_short_intervals) {
+	time_sup.inf.c.parmon.cdata.short_check_interval
+	    = ERTS_INIT_SHORT_INTERVAL_COUNTER;
+    }
+    else if ((os_mtime - time_sup.inf.c.parmon.cdata.last_check
+	      >= ERTS_SHORT_TIME_CORRECTION_CHECK - ERTS_MONOTONIC_TIME_UNIT)
+	     && time_sup.inf.c.parmon.cdata.short_check_interval > 0) {
+	time_sup.inf.c.parmon.cdata.short_check_interval--;
+    }
+    time_sup.inf.c.parmon.cdata.last_check = os_mtime;
+
+    if (new_correction.error == 0)
+	timeout = ERTS_MONOTONIC_TO_MSEC(ERTS_LONG_TIME_CORRECTION_CHECK);
+    else {
+	ErtsMonotonicTime ecorr = new_correction.error;
+	if (sdiff < 0)
+	    sdiff = -1*sdiff;
+	if (ecorr < 0)
+	    ecorr = -1*ecorr;
+	if (sdiff > ecorr*(ERTS_LONG_TIME_CORRECTION_CHECK/ERTS_TCORR_ERR_UNIT))
+	    timeout = ERTS_MONOTONIC_TO_MSEC(ERTS_LONG_TIME_CORRECTION_CHECK);
+	else {
+	    timeout = ERTS_MONOTONIC_TO_MSEC((ERTS_TCORR_ERR_UNIT*sdiff)/ecorr);
+	    if (timeout < 10)
+		timeout = 10;
 	}
     }
-    tv->tv_sec += (int) (diff_time / ((SysHrTime) 1000000));
-    tv->tv_usec += (int) (diff_time % ((SysHrTime) 1000000));
-    if (tv->tv_usec >= 1000000) {
-	tv->tv_usec -= 1000000;
-	tv->tv_sec += 1;
+
+    if (timeout > ERTS_MONOTONIC_TO_MSEC(ERTS_SHORT_TIME_CORRECTION_CHECK)
+	&& time_sup.inf.c.parmon.cdata.short_check_interval) {
+	timeout = ERTS_MONOTONIC_TO_MSEC(ERTS_SHORT_TIME_CORRECTION_CHECK);
     }
-    hr_last_time = curr;
-}
+    
+    if (set_new_correction) {
+	erts_smp_rwmtx_rwlock(&time_sup.inf.c.parmon.rwmtx);
 
-#define correction (hr_correction/1000000)
+	os_mtime = erts_os_monotonic_time();
 
-#else /* !HAVE_GETHRTIME */
-#if !defined(CORRECT_USING_TIMES) 
-#define init_tolerant_timeofday() 
-#define get_tolerant_timeofday(tvp) sys_gettimeofday(tvp)
-#else
+	/* Save previous correction instance */
+	time_sup.inf.c.parmon.cdata.prev = *cip;
 
-typedef Sint64 Milli;
-
-static clock_t init_ct;
-static Sint64 ct_wrap;
-static Milli init_tv_m;
-static Milli correction_supress; 
-static Milli last_ct_diff;
-static Milli last_cc; 
-static clock_t last_ct;
-
-/* sys_times() might need to be wrapped and the values shifted (right)
-   a bit to cope with newer linux (2.5.*) kernels, this has to be taken care 
-   of dynamically to start with, a special version that uses
-   the times() return value as a high resolution timer can be made
-   to fully utilize the faster ticks, like on windows, but for now, we'll
-   settle with this silly workaround */
-#ifdef ERTS_WRAP_SYS_TIMES 
-#define KERNEL_TICKS() (sys_times_wrap() &  \
-			((1UL << ((sizeof(clock_t) * 8) - 1)) - 1)) 
-#else
-SysTimes dummy_tms;
+	/*
+	 * Current correction instance begin when
+	 * OS monotonic time has increased one unit.
+	 */
+	os_mtime++;
 
-#define KERNEL_TICKS() (sys_times(&dummy_tms) &  \
-			((1UL << ((sizeof(clock_t) * 8) - 1)) - 1)) 
+	/*
+	 * Erlang monotonic time corresponding to
+	 * next OS monotonic time using previous
+	 * correction.
+	 */
+	erl_mtime = calc_corrected_erl_mtime(os_mtime, cip, NULL);
 
-#endif
+	/*
+	 * Save new current correction instance.
+	 */
+	time_sup.inf.c.parmon.cdata.curr.erl_mtime = erl_mtime;
+	time_sup.inf.c.parmon.cdata.curr.os_mtime = os_mtime;
+	time_sup.inf.c.parmon.cdata.curr.correction = new_correction;
 
-static void init_tolerant_timeofday(void)
-{
-    last_ct = init_ct = KERNEL_TICKS();
-    last_cc = 0;
-    init_tv_m = (((Milli) inittv.tv_sec) * 1000) + 
-	(inittv.tv_usec / 1000);
-    ct_wrap = 0;
-    correction_supress = 0;
+	erts_smp_rwmtx_rwunlock(&time_sup.inf.c.parmon.rwmtx);
+    }
+
+    erts_set_timer(&time_sup.inf.c.parmon.timer,
+		   check_time_correction,
+		   NULL,
+		   NULL,
+		   timeout);
 }
 
+#ifndef ERTS_HAVE_CORRECTED_OS_MONOTONIC
 
-static void get_tolerant_timeofday(SysTimeval *tvp)
+static void
+init_check_time_correction(void *unused)
 {
-    clock_t current_ct;
-    SysTimeval current_tv;
-    Milli ct_diff;
-    Milli tv_diff;
-    Milli current_correction;
-    Milli act_correction;	/* long shown to be too small */
-    Milli max_adjust;
-
-    if (erts_disable_tolerant_timeofday) {
-	sys_gettimeofday(tvp);
-	return;
+    ErtsMonotonicDriftData *ddp;
+    ErtsMonotonicTime old_mtime, old_stime, mtime, stime, mtime_diff, stime_diff;
+    int ix;
+    SysTimeval tod;
+
+    ddp = &time_sup.inf.c.parmon.cdata.drift;
+    ix = ddp->ix;
+    old_mtime = ddp->intervals[0].time.mon;
+    old_stime = ddp->intervals[0].time.sys;
+
+    mtime = erts_os_monotonic_time();
+    sys_gettimeofday(&tod);
+
+    stime = ERTS_SEC_TO_MONOTONIC(tod.tv_sec);
+    stime += ERTS_USEC_TO_MONOTONIC(tod.tv_usec);
+
+    mtime_diff = mtime - old_mtime;
+    stime_diff = stime - old_stime;
+    if (100*stime_diff  < 80*mtime_diff || 120*mtime_diff < 100*stime_diff ) {
+	/* Had a system time leap... pretend no drift... */
+	stime_diff = mtime_diff;
+    }
+    
+    /*
+     * We use old time values in order to trigger
+     * a drift adjustment, and repeat this interval
+     * in all slots...
+     */
+    for (ix = 0; ix < ERTS_DRIFT_INTERVALS; ix++) {
+	ddp->intervals[ix].diff.mon = mtime_diff;
+	ddp->intervals[ix].diff.sys = stime_diff;
+	ddp->intervals[ix].time.mon = old_mtime;
+	ddp->intervals[ix].time.sys = old_stime;
     }
 
-#ifdef ERTS_WRAP_SYS_TIMES 
-#define TICK_MS (1000 / SYS_CLK_TCK_WRAP)
+    ddp->acc.sys = stime_diff*ERTS_DRIFT_INTERVALS;
+    ddp->acc.mon = mtime_diff*ERTS_DRIFT_INTERVALS;
+    ddp->ix = 0;
+    ddp->dirty_counter = ERTS_DRIFT_INTERVALS;
+
+    check_time_correction(NULL);
+}
+
+#endif
+
+static ErtsMonotonicTime
+finalize_corrected_time_offset(SysTimeval *todp)
+{
+    ErtsMonotonicTime os_mtime;
+    ErtsMonotonicCorrectionData cdata;
+    ErtsMonotonicCorrectionInstance *cip;
+
+    erts_smp_rwmtx_rlock(&time_sup.inf.c.parmon.rwmtx);
+
+    os_mtime = erts_os_monotonic_time();
+    sys_gettimeofday(todp);
+
+    cdata = time_sup.inf.c.parmon.cdata;
+
+    erts_smp_rwmtx_runlock(&time_sup.inf.c.parmon.rwmtx);
+
+    if (os_mtime < cdata.curr.os_mtime)
+	erl_exit(ERTS_ABORT_EXIT,
+		 "OS monotonic time stepped backwards\n");
+    cip = &cdata.curr;
+
+    return calc_corrected_erl_mtime(os_mtime, cip, NULL);
+}
+
+static void
+late_init_time_correction(void)
+{
+    if (time_sup.inf.c.finalized_offset) {
+	erts_set_timer(&time_sup.inf.c.parmon.timer,
+#ifndef ERTS_HAVE_CORRECTED_OS_MONOTONIC
+		       init_check_time_correction,
 #else
-#define TICK_MS (1000 / SYS_CLK_TCK)
+		       check_time_correction,
 #endif
-    current_ct = KERNEL_TICKS();
-    sys_gettimeofday(&current_tv);
-
-    /* I dont know if uptime can move some units backwards
-       on some systems, but I allow for small backward 
-       jumps to avoid such problems if they exist...*/
-    if (last_ct > 100 && current_ct < (last_ct - 100)) {
-	ct_wrap += ((Sint64) 1) << ((sizeof(clock_t) * 8) - 1);
+		       NULL,
+		       NULL,
+		       ERTS_MONOTONIC_TO_MSEC(ERTS_SHORT_TIME_CORRECTION_CHECK));
     }
-    last_ct = current_ct;
-    ct_diff = ((ct_wrap + current_ct) - init_ct) * TICK_MS;
+}
 
-    /*
-     * We will adjust the time in milliseconds and we allow for 1% 
-     * adjustments, but if this function is called more often then every 100 
-     * millisecond (which is obviously possible), we will never adjust, so 
-     * we accumulate small times by setting last_ct_diff iff max_adjust > 0
-     */
-    if ((max_adjust = (ct_diff - last_ct_diff)/100) > 0)
-	last_ct_diff = ct_diff;
+#endif /* ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT */
 
-    tv_diff = ((((Milli) current_tv.tv_sec) * 1000) + 
-	       (current_tv.tv_usec / 1000)) - init_tv_m;
+static ErtsMonotonicTime get_not_corrected_time(void)
+{
+    SysTimeval tmp_tv;
+    ErtsMonotonicTime stime, mtime;
 
-    current_correction = ((ct_diff - tv_diff) / TICK_MS) * TICK_MS; /* trunc */
+    erts_smp_mtx_lock(&erts_get_time_mtx);
 
-    /* 
-     * We allow the current_correction value to wobble a little, as it
-     * suffers from the low resolution of the kernel ticks. 
-     * if it hasn't changed more than one tick in either direction, 
-     * we will keep the old value.
-     */
-    if ((last_cc > current_correction + TICK_MS) ||
-	(last_cc < current_correction - TICK_MS)) {
-	last_cc = current_correction;
-    } else {
-	current_correction = last_cc;
-    }
-    
-    /*
-     * As time goes, we try to get the actual correction to 0, 
-     * that is, make erlangs time correspond to the systems dito.
-     * The act correction is what we seem to need (current_correction)
-     * minus the correction suppression. The correction supression
-     * will change slowly (max 1% of elapsed time) but in millisecond steps.
-     */
-    act_correction = current_correction - correction_supress;
-    if (max_adjust > 0) {
-	/*
-	 * Here we slowly adjust erlangs time to correspond with the 
-	 * system time by changing the correction_supress variable.
-	 * It can change max_adjust milliseconds which is 1% of elapsed time
-	 */
-	if (act_correction > 0) {
-	    if (current_correction - correction_supress > max_adjust) {
-		correction_supress += max_adjust;
-	    } else {
-		correction_supress = current_correction;
-	    }
-	    act_correction = current_correction - correction_supress;
-	} else if (act_correction < 0) {
-	    if (correction_supress - current_correction > max_adjust) {
-		correction_supress -= max_adjust;
-	    } else {
-		correction_supress = current_correction;
+    sys_gettimeofday(&tmp_tv);
+
+    stime = ERTS_SEC_TO_MONOTONIC(tmp_tv.tv_sec);
+    stime += ERTS_USEC_TO_MONOTONIC(tmp_tv.tv_usec);
+
+    mtime = stime - time_sup.inf.c.not_corrected_moffset;
+
+    if (mtime >= time_sup.f.c.last_not_corrected_time)
+	time_sup.f.c.last_not_corrected_time = mtime;
+    else {
+	mtime = time_sup.f.c.last_not_corrected_time;
+
+	if (time_sup.r.o.warp_mode == ERTS_MULTI_TIME_WARP_MODE) {
+	    ErtsMonotonicTime new_offset = stime - mtime;
+	    new_offset = ERTS_MONOTONIC_TO_USEC(new_offset);
+	    new_offset = ERTS_USEC_TO_MONOTONIC(new_offset);
+	    if (time_sup.inf.c.not_corrected_moffset != new_offset) {
+		time_sup.inf.c.not_corrected_moffset = new_offset;
+		set_time_offset(new_offset);
+		schedule_send_time_offset_changed_notifications(new_offset);
 	    }
-	    act_correction = current_correction - correction_supress;
 	}
+
     }
-    /*
-     * The actual correction will correct the timeval so that system 
-     * time warps gets smothed down.
-     */
-    current_tv.tv_sec += act_correction / 1000;
-    current_tv.tv_usec += (act_correction % 1000) * 1000;
-
-    if (current_tv.tv_usec >= 1000000) {
-	++current_tv.tv_sec ;
-	current_tv.tv_usec -= 1000000;
-    } else if (current_tv.tv_usec < 0) {
-	--current_tv.tv_sec;
-	current_tv.tv_usec += 1000000;
-    }
-    *tvp = current_tv;
-#undef TICK_MS
+
+    ASSERT(stime == mtime + time_sup.inf.c.not_corrected_moffset);
+
+    erts_smp_mtx_unlock(&erts_get_time_mtx);
+
+    return mtime;
 }
 
-#endif /* CORRECT_USING_TIMES */
-#endif /* !HAVE_GETHRTIME */
+int erts_check_time_adj_support(int time_correction,
+				ErtsTimeWarpMode time_warp_mode)
+{
+    if (!time_correction)
+	return 1;
 
-/*
-** Why this? Well, most platforms have a constant clock resolution of 1,
-** we dont want the deliver_time/time_remaining routines to waste 
-** time dividing and multiplying by/with a variable that's always one.
-** so the return value of sys_init_time is ignored on those platforms.
-*/
- 
-#ifndef SYS_CLOCK_RESOLUTION
-static int clock_resolution;
-#define CLOCK_RESOLUTION clock_resolution
+    /* User wants time correction */
+
+#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+    return !time_sup.r.o.os_monotonic_disable;
 #else
-#define CLOCK_RESOLUTION SYS_CLOCK_RESOLUTION
+    return 0;
 #endif
+}
 
-/*
-** The clock resolution should really be the resolution of the 
-** time function in use, which on most platforms 
-** is 1. On VxWorks the resolution should be
-** the number of ticks per second (or 1, which would work nicely to).
-**
-** Setting lower resolutions is mostly interesting when timers are used
-** instead of something like select.
-*/
-
-static SysTimeval last_delivered; 
-
-static void init_erts_deliver_time(const SysTimeval *inittv)
+int
+erts_has_time_correction(void)
 {
-    /* We set the initial values for deliver_time here */
-    last_delivered = *inittv;
-    last_delivered.tv_usec = 1000 * (last_delivered.tv_usec / 1000); 
-                                                   /* ms resolution */
+    return time_sup.r.o.correction;
 }
 
-static void do_erts_deliver_time(const SysTimeval *current)
+void
+erts_early_init_time_sup(void)
 {
-    SysTimeval cur_time;
-    erts_time_t elapsed;
-    
-    /* calculate and deliver appropriate number of ticks */
-    cur_time = *current;
-    cur_time.tv_usec = 1000 * (cur_time.tv_usec / 1000); /* ms resolution */
-    elapsed = (1000 * (cur_time.tv_sec - last_delivered.tv_sec) +
-	       (cur_time.tv_usec - last_delivered.tv_usec) / 1000) / 
-	CLOCK_RESOLUTION;
+    ErtsSysInitTimeResult sys_init_time_res
+	= ERTS_SYS_INIT_TIME_RESULT_INITER;
 
-    /* Sometimes the time jump backwards,
-       resulting in a negative elapsed time. We compensate for
-       this by simply pretend as if the time stood still. :) */
+    sys_init_time(&sys_init_time_res);
 
-    if (elapsed > 0) {
+    erts_time_sup__.r.o.monotonic_time_unit
+	= sys_init_time_res.os_monotonic_time_unit;
 
-	ASSERT(elapsed < ((erts_time_t) ERTS_SHORT_TIME_T_MAX));
+#ifndef SYS_CLOCK_RESOLUTION
+    erts_time_sup__.r.o.clktck_resolution
+	= sys_init_time_res.sys_clock_resolution;
+    erts_time_sup__.r.o.clktck_resolution *= 1000;
+#endif
 
-	erts_do_time_add((erts_short_time_t) elapsed);
-	last_delivered = cur_time;
-    }
+#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+    time_sup.r.o.os_monotonic_disable
+	= !sys_init_time_res.have_os_monotonic;
+    time_sup.r.o.os_monotonic_func
+	= sys_init_time_res.os_monotonic_info.func;
+    time_sup.r.o.os_monotonic_clock_id
+	= sys_init_time_res.os_monotonic_info.clock_id;
+    time_sup.r.o.os_monotonic_locked
+	= sys_init_time_res.os_monotonic_info.locked_use;
+    time_sup.r.o.os_monotonic_resolution
+	= sys_init_time_res.os_monotonic_info.resolution;
+#endif
 }
 
 int 
-erts_init_time_sup(void)
+erts_init_time_sup(int time_correction, ErtsTimeWarpMode time_warp_mode)
 {
+#if !ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT
+    ErtsMonotonicTime abs_start;
+#endif
+
+    ASSERT(ERTS_MONOTONIC_TIME_MIN < ERTS_MONOTONIC_TIME_MAX);
+
     erts_smp_mtx_init(&erts_timeofday_mtx, "timeofday");
+    erts_smp_mtx_init(&erts_get_time_mtx, "get_time");
+
+    time_sup.r.o.correction = time_correction;
+    time_sup.r.o.warp_mode = time_warp_mode;
+ 
+    if (time_warp_mode == ERTS_SINGLE_TIME_WARP_MODE)
+	time_sup.inf.c.finalized_offset = 0;
+    else
+	time_sup.inf.c.finalized_offset = ~0;
+
+#if !ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT
+
+#ifdef ARCH_32
+    time_sup.r.o.start = ((((ErtsMonotonicTime) 1) << 32)-1);
+    time_sup.r.o.start /= ERTS_MONOTONIC_TIME_UNIT;
+    time_sup.r.o.start *= ERTS_MONOTONIC_TIME_UNIT;
+    time_sup.r.o.start += ERTS_MONOTONIC_TIME_UNIT;
+    abs_start = time_sup.r.o.start;
+#else /* ARCH_64 */
+    if (ERTS_MONOTONIC_TIME_UNIT <= 1000*1000)
+	abs_start = time_sup.r.o.start = 0;
+    else {
+	time_sup.r.o.start = ((ErtsMonotonicTime) MIN_SMALL);
+	time_sup.r.o.start /= ERTS_MONOTONIC_TIME_UNIT;
+	time_sup.r.o.start *= ERTS_MONOTONIC_TIME_UNIT;
+	abs_start = -1*time_sup.r.o.start;
+    }
+#endif
 
-    init_approx_time();
+    time_sup.r.o.start_offset.native = time_sup.r.o.start;
+    time_sup.r.o.start_offset.nsec = (ErtsMonotonicTime)
+	erts_time_unit_conversion((Uint64) abs_start,
+				  (Uint32) ERTS_MONOTONIC_TIME_UNIT,
+				  (Uint32) 1000*1000*1000);
+    time_sup.r.o.start_offset.usec = (ErtsMonotonicTime)
+	erts_time_unit_conversion((Uint64) abs_start,
+				  (Uint32) ERTS_MONOTONIC_TIME_UNIT,
+				  (Uint32) 1000*1000);
+    time_sup.r.o.start_offset.msec = (ErtsMonotonicTime)
+	erts_time_unit_conversion((Uint64) abs_start,
+				  (Uint32) ERTS_MONOTONIC_TIME_UNIT,
+				  (Uint32) 1000);
+    time_sup.r.o.start_offset.sec = (ErtsMonotonicTime)
+	erts_time_unit_conversion((Uint64) abs_start,
+				  (Uint32) ERTS_MONOTONIC_TIME_UNIT,
+				  (Uint32) 1);
+    if (time_sup.r.o.start < 0) {
+	time_sup.r.o.start_offset.nsec *= -1;
+	time_sup.r.o.start_offset.usec *= -1;
+	time_sup.r.o.start_offset.msec *= -1;
+	time_sup.r.o.start_offset.sec *= -1;
+    }
 
-    last_emu_time.tv_sec = 0;
-    last_emu_time.tv_usec = 0;
+#endif
 
-#ifndef SYS_CLOCK_RESOLUTION
-    clock_resolution = sys_init_time();
+    if (ERTS_MONOTONIC_TIME_UNIT < ERTS_CLKTCK_RESOLUTION)
+	ERTS_INTERNAL_ERROR("Too small monotonic time time unit");
+
+#ifndef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+    time_sup.r.o.correction = 0;
 #else
-    (void) sys_init_time();
-#endif
-    sys_gettimeofday(&inittv);
+    if (time_sup.r.o.os_monotonic_disable)
+	time_sup.r.o.correction = 0;
+
+    if (time_sup.r.o.correction) {
+	ErtsMonotonicCorrectionData *cdatap;
+	erts_smp_rwmtx_opt_t rwmtx_opts = ERTS_SMP_RWMTX_OPT_DEFAULT_INITER;
+	ErtsMonotonicTime offset;
+	time_sup.inf.c.minit = erts_os_monotonic_time();
+	sys_gettimeofday(&time_sup.inf.c.inittv);
+	time_sup.r.o.moffset = -1*time_sup.inf.c.minit;
+	offset = ERTS_SEC_TO_MONOTONIC(time_sup.inf.c.inittv.tv_sec);
+	offset += ERTS_USEC_TO_MONOTONIC(time_sup.inf.c.inittv.tv_usec);
+	init_time_offset(offset);
+
+	rwmtx_opts.type = ERTS_SMP_RWMTX_TYPE_EXTREMELY_FREQUENT_READ;
+	rwmtx_opts.lived = ERTS_SMP_RWMTX_LONG_LIVED;
+
+	erts_smp_rwmtx_init_opt(&time_sup.inf.c.parmon.rwmtx,
+				&rwmtx_opts, "get_corrected_time");
+
+	cdatap = &time_sup.inf.c.parmon.cdata;
     
-#ifdef HAVE_GETHRTIME
-    sys_init_hrtime();
+#ifndef ERTS_HAVE_CORRECTED_OS_MONOTONIC
+	cdatap->drift.intervals[0].time.sys
+	    = ERTS_SEC_TO_MONOTONIC(time_sup.inf.c.inittv.tv_sec);
+	cdatap->drift.intervals[0].time.sys
+	    += ERTS_USEC_TO_MONOTONIC(time_sup.inf.c.inittv.tv_usec);
+	cdatap->drift.intervals[0].time.mon = time_sup.inf.c.minit;
+	cdatap->curr.correction.drift = 0;
+#endif
+	cdatap->curr.correction.error = 0;
+	cdatap->curr.erl_mtime = 0;
+	cdatap->curr.os_mtime = time_sup.inf.c.minit;
+	cdatap->last_check = time_sup.inf.c.minit;
+	cdatap->short_check_interval = ERTS_INIT_SHORT_INTERVAL_COUNTER;
+	cdatap->prev = cdatap->curr;
+
+	time_sup.r.o.get_time = get_corrected_time;
+    }
+    else
 #endif
-    init_tolerant_timeofday();
+    {
+	ErtsMonotonicTime stime, offset;
+	time_sup.r.o.get_time = get_not_corrected_time;
+	stime = ERTS_SEC_TO_MONOTONIC(time_sup.inf.c.inittv.tv_sec);
+	stime += ERTS_USEC_TO_MONOTONIC(time_sup.inf.c.inittv.tv_usec);
+	offset = stime;
+	time_sup.inf.c.not_corrected_moffset = offset;
+	init_time_offset(offset);
+	time_sup.f.c.last_not_corrected_time = 0;
+    }
+
+    prev_wall_clock_elapsed = 0;
 
-    init_erts_deliver_time(&inittv);
-    gtv = inittv;
-    then.tv_sec = then.tv_usec = 0;
+    previous_now = ERTS_MONOTONIC_TO_USEC(get_time_offset());
 
-    erts_deliver_time();
+#ifdef DEBUG
+    time_sup_initialized = 1;
+#endif
 
-    return CLOCK_RESOLUTION;
+    return ERTS_CLKTCK_RESOLUTION/1000;
 }    
+
+void
+erts_late_init_time_sup(void)
+{
+#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+    /* Timer wheel must be initialized */
+    if (time_sup.r.o.get_time == get_corrected_time)
+	late_init_time_correction();
+#endif
+}
+
+ErtsTimeWarpMode erts_time_warp_mode(void)
+{
+    return time_sup.r.o.warp_mode;
+}
+
+ErtsTimeOffsetState erts_time_offset_state(void)
+{
+    switch (time_sup.r.o.warp_mode) {
+    case ERTS_NO_TIME_WARP_MODE:
+	return ERTS_TIME_OFFSET_FINAL;
+    case ERTS_SINGLE_TIME_WARP_MODE:
+	if (time_sup.inf.c.finalized_offset)
+	    return ERTS_TIME_OFFSET_FINAL;
+	return ERTS_TIME_OFFSET_PRELIMINARY;
+    case ERTS_MULTI_TIME_WARP_MODE:
+	return ERTS_TIME_OFFSET_VOLATILE;
+    default:
+	ERTS_INTERNAL_ERROR("Invalid time warp mode");
+	return ERTS_TIME_OFFSET_VOLATILE;
+    }
+}
+
+/*
+ * erts_finalize_time_offset() will only change time offset
+ * the first time it is called when the emulator has been
+ * started in "single time warp" mode. Returns previous
+ * state:
+ * * ERTS_TIME_OFFSET_PRELIMINARY - Finalization performed
+ * * ERTS_TIME_OFFSET_FINAL - Already finialized; nothing changed
+ * * ERTS_TIME_OFFSET_VOLATILE - Not supported, either in
+ * * no correction mode (or multi time warp mode; not yet implemented).
+ */
+
+ErtsTimeOffsetState
+erts_finalize_time_offset(void)
+{
+    switch (time_sup.r.o.warp_mode) {
+    case ERTS_NO_TIME_WARP_MODE:
+	return ERTS_TIME_OFFSET_FINAL;
+    case ERTS_MULTI_TIME_WARP_MODE:
+	return ERTS_TIME_OFFSET_VOLATILE;
+    case ERTS_SINGLE_TIME_WARP_MODE: {
+	ErtsTimeOffsetState res = ERTS_TIME_OFFSET_FINAL;
+
+	erts_smp_mtx_lock(&erts_get_time_mtx);
+
+	if (!time_sup.inf.c.finalized_offset) {
+	    ErtsMonotonicTime mtime, new_offset;
+	    SysTimeval tv;
+
+#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+	    if (!time_sup.r.o.correction)
+#endif
+	    {
+		ErtsMonotonicTime stime;
+		sys_gettimeofday(&tv);
+
+		stime = ERTS_SEC_TO_MONOTONIC(tv.tv_sec);
+		stime += ERTS_USEC_TO_MONOTONIC(tv.tv_usec);
+
+		mtime = stime - time_sup.inf.c.not_corrected_moffset;
+
+		if (mtime >= time_sup.f.c.last_not_corrected_time) {
+		    time_sup.f.c.last_not_corrected_time = mtime;
+		    new_offset = time_sup.inf.c.not_corrected_moffset;
+		}
+		else {
+		    mtime = time_sup.f.c.last_not_corrected_time;
+
+		    ASSERT(time_sup.inf.c.not_corrected_moffset != stime - mtime);
+		    new_offset = stime - mtime;
+		    time_sup.inf.c.not_corrected_moffset = new_offset;
+		}
+
+	    }
+#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+	    else {
+		mtime = finalize_corrected_time_offset(&tv);
+		new_offset = ERTS_SEC_TO_MONOTONIC(tv.tv_sec);
+		new_offset += ERTS_USEC_TO_MONOTONIC(tv.tv_usec);
+		new_offset -= mtime;
+
+	    }
+#endif
+	    new_offset = ERTS_MONOTONIC_TO_USEC(new_offset);
+	    new_offset = ERTS_USEC_TO_MONOTONIC(new_offset);
+
+	    set_time_offset(new_offset);
+	    schedule_send_time_offset_changed_notifications(new_offset);
+
+	    time_sup.inf.c.finalized_offset = ~0;
+	    res = ERTS_TIME_OFFSET_PRELIMINARY;
+	}
+
+	erts_smp_mtx_unlock(&erts_get_time_mtx);
+
+#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+	if (res == ERTS_TIME_OFFSET_PRELIMINARY
+	    && time_sup.r.o.get_time == get_corrected_time) {
+	    late_init_time_correction();
+	}
+#endif
+
+	return res;
+    }
+    default:
+	ERTS_INTERNAL_ERROR("Invalid time warp mode");
+	return ERTS_TIME_OFFSET_VOLATILE;
+    }
+}
+
 /* info functions */
 
 void 
@@ -498,23 +1090,16 @@ elapsed_time_both(UWord *ms_user, UWord *ms_sys,
 void 
 wall_clock_elapsed_time_both(UWord *ms_total, UWord *ms_diff)
 {
-    UWord prev_total;
-    SysTimeval tv;
+    ErtsMonotonicTime now, elapsed;
 
     erts_smp_mtx_lock(&erts_timeofday_mtx);
 
-    get_tolerant_timeofday(&tv);
+    now = time_sup.r.o.get_time();
 
-    *ms_total = 1000 * (tv.tv_sec - inittv.tv_sec) +
-	(tv.tv_usec - inittv.tv_usec) / 1000;
-
-    prev_total = 1000 * (gtv.tv_sec - inittv.tv_sec) +
-	(gtv.tv_usec - inittv.tv_usec) / 1000;
-    *ms_diff = *ms_total - prev_total;
-    gtv = tv;
-
-    /* must sync the machine's idea of time here */
-    do_erts_deliver_time(&tv);
+    elapsed = ERTS_MONOTONIC_TO_MSEC(now);
+    *ms_total = (UWord) elapsed;
+    *ms_diff = (UWord) (elapsed - prev_wall_clock_elapsed);
+    prev_wall_clock_elapsed = elapsed;
 
     erts_smp_mtx_unlock(&erts_timeofday_mtx);
 }
@@ -890,38 +1475,41 @@ univ_to_local(Sint *year, Sint *month, Sint *day,
     return 0;
 }
 
-
 /* get a timestamp */
 void
 get_now(Uint* megasec, Uint* sec, Uint* microsec)
 {
-    SysTimeval now;
+    ErtsMonotonicTime now_megasec, now_sec, now, mtime, time_offset;
     
+    mtime = time_sup.r.o.get_time();
+    time_offset = get_time_offset();
+    now = ERTS_MONOTONIC_TO_USEC(mtime + time_offset);
+
     erts_smp_mtx_lock(&erts_timeofday_mtx);
-    
-    get_tolerant_timeofday(&now);
-    do_erts_deliver_time(&now);
-
-    /* Make sure time is later than last */
-    if (then.tv_sec > now.tv_sec ||
-	(then.tv_sec == now.tv_sec && then.tv_usec >= now.tv_usec)) {
-	now = then;
-	now.tv_usec++;
-    }
-    /* Check for carry from above + general reasonability */
-    if (now.tv_usec >= 1000000) {
-	now.tv_usec = 0;
-	now.tv_sec++;
-    }
-    then = now;
+
+    /* Make sure now time is later than last time */
+    if (now <= previous_now)
+	now = previous_now + 1;
+
+    previous_now = now;
     
     erts_smp_mtx_unlock(&erts_timeofday_mtx);
-    
-    *megasec = (Uint) (now.tv_sec / 1000000);
-    *sec = (Uint) (now.tv_sec % 1000000);
-    *microsec = (Uint) (now.tv_usec);
 
-    update_approx_time(&now);
+    now_megasec = now / ERTS_MONOTONIC_TIME_TERA;
+    now_sec = now / ERTS_MONOTONIC_TIME_MEGA;
+    *megasec = (Uint) now_megasec;
+    *sec = (Uint) (now_sec - now_megasec*ERTS_MONOTONIC_TIME_MEGA);
+    *microsec = (Uint) (now - now_sec*ERTS_MONOTONIC_TIME_MEGA);
+
+    ASSERT(((ErtsMonotonicTime) *megasec)*ERTS_MONOTONIC_TIME_TERA
+	   + ((ErtsMonotonicTime) *sec)*ERTS_MONOTONIC_TIME_MEGA
+	   + ((ErtsMonotonicTime) *microsec) == now);
+}
+
+ErtsMonotonicTime
+erts_get_monotonic_time(void)
+{
+    return time_sup.r.o.get_time();
 }
 
 void
@@ -934,102 +1522,465 @@ get_sys_now(Uint* megasec, Uint* sec, Uint* microsec)
     *megasec = (Uint) (now.tv_sec / 1000000);
     *sec = (Uint) (now.tv_sec % 1000000);
     *microsec = (Uint) (now.tv_usec);
-
-    update_approx_time(&now);
 }
 
+#ifdef HAVE_ERTS_NOW_CPU
+void erts_get_now_cpu(Uint* megasec, Uint* sec, Uint* microsec) {
+  SysCpuTime t;
+  SysTimespec tp;
 
-/* deliver elapsed *ticks* to the machine - takes a pointer
-   to a struct timeval representing current time (to save
-   a gettimeofday() where possible) or NULL */
+  sys_get_proc_cputime(t, tp);
+  *microsec = (Uint)(tp.tv_nsec / 1000);
+  t = (tp.tv_sec / 1000000);
+  *megasec = (Uint)(t % 1000000);
+  *sec = (Uint)(tp.tv_sec % 1000000);
+}
+#endif
 
-void erts_deliver_time(void) {
-    SysTimeval now;
-    
-    erts_smp_mtx_lock(&erts_timeofday_mtx);
-    
-    get_tolerant_timeofday(&now);
-    do_erts_deliver_time(&now);
-    
-    erts_smp_mtx_unlock(&erts_timeofday_mtx);
+#include "big.h"
 
-    update_approx_time(&now);
+void
+erts_monitor_time_offset(Eterm id, Eterm ref)
+{
+    erts_smp_mtx_lock(&erts_get_time_mtx);
+    erts_add_monitor(&time_offset_monitors, MON_TIME_OFFSET, ref, id, NIL);
+    no_time_offset_monitors++;
+    erts_smp_mtx_unlock(&erts_get_time_mtx);
+}
+
+int
+erts_demonitor_time_offset(Eterm ref)
+{
+    int res;
+    ErtsMonitor *mon;
+    ASSERT(is_internal_ref(ref));
+    erts_smp_mtx_lock(&erts_get_time_mtx);
+    mon = erts_remove_monitor(&time_offset_monitors, ref);
+    if (!mon)
+	res = 0;
+    else {
+	ASSERT(no_time_offset_monitors > 0);
+	no_time_offset_monitors--;
+	res = 1;
+    }
+    erts_smp_mtx_unlock(&erts_get_time_mtx);
+    if (res)
+	erts_destroy_monitor(mon);
+    return res;
 }
 
-/* get *real* time (not ticks) remaining until next timeout - if there
-   isn't one, give a "long" time, that is guaranteed
-   to not cause overflow when we report elapsed time later on */
+typedef struct {
+    Eterm pid;
+    Eterm ref;
+    Eterm heap[REF_THING_SIZE];
+} ErtsTimeOffsetMonitorInfo;
+
+typedef struct {
+    Uint ix;
+    ErtsTimeOffsetMonitorInfo *to_mon_info;
+} ErtsTimeOffsetMonitorContext;
 
-void erts_time_remaining(SysTimeval *rem_time)
+static void
+save_time_offset_monitor(ErtsMonitor *mon, void *vcntxt)
 {
-    erts_time_t ticks;
-    SysTimeval cur_time;
-    erts_time_t elapsed;
-
-    /* erts_next_time() returns no of ticks to next timeout or -1 if none */
-
-    ticks = (erts_time_t) erts_next_time();
-    if (ticks == (erts_time_t) -1) {
-	/* timer queue empty */
-	/* this will cause at most 100000000 ticks */
-	rem_time->tv_sec = 100000;
-	rem_time->tv_usec = 0;
-    } else {
-	/* next timeout after ticks ticks */
-	ticks *= CLOCK_RESOLUTION;
-	
-	erts_smp_mtx_lock(&erts_timeofday_mtx);
-	
-	get_tolerant_timeofday(&cur_time);
-	cur_time.tv_usec = 1000 * 
-	    (cur_time.tv_usec / 1000);/* ms resolution*/
-	elapsed = 1000 * (cur_time.tv_sec - last_delivered.tv_sec) +
-	    (cur_time.tv_usec - last_delivered.tv_usec) / 1000;
-	
-	erts_smp_mtx_unlock(&erts_timeofday_mtx);
+    ErtsTimeOffsetMonitorContext *cntxt;
+    Eterm *from_hp, *to_hp;
+    Uint mix;
+    int hix;
+
+    cntxt = (ErtsTimeOffsetMonitorContext *) vcntxt;
+    mix = (cntxt->ix)++;
+    cntxt->to_mon_info[mix].pid = mon->pid;
+    to_hp = &cntxt->to_mon_info[mix].heap[0];
+
+    ASSERT(is_internal_ref(mon->ref));
+    from_hp = internal_ref_val(mon->ref);
+    ASSERT(thing_arityval(*from_hp) + 1 == REF_THING_SIZE);
+
+    for (hix = 0; hix < REF_THING_SIZE; hix++)
+	to_hp[hix] = from_hp[hix];
+
+    cntxt->to_mon_info[mix].ref
+	= make_internal_ref(&cntxt->to_mon_info[mix].heap[0]);
+
+}
+
+static void
+send_time_offset_changed_notifications(void *new_offsetp)
+{
+    ErtsMonotonicTime new_offset;
+    ErtsTimeOffsetMonitorInfo *to_mon_info;
+    Uint no_monitors;
+    char *tmp = NULL;
+
+#ifdef ARCH_64
+    new_offset = (ErtsMonotonicTime) new_offsetp;
+#else
+    new_offset = *((ErtsMonotonicTime *) new_offsetp);
+    erts_free(ERTS_ALC_T_NEW_TIME_OFFSET, new_offsetp);
+#endif
+    new_offset -= ERTS_MONOTONIC_OFFSET_NATIVE;
+
+    erts_smp_mtx_lock(&erts_get_time_mtx);
+
+    no_monitors = no_time_offset_monitors;
+    if (no_monitors) {
+	ErtsTimeOffsetMonitorContext cntxt;
+	Uint alloc_sz;
 	
-	if (ticks <= elapsed) { /* Ooops, better hurry */
-	    rem_time->tv_sec = rem_time->tv_usec = 0;
-	    return;
+	/* Monitor info array size */
+	alloc_sz = no_monitors*sizeof(ErtsTimeOffsetMonitorInfo);
+	/* + template max size */
+	alloc_sz += 6*sizeof(Eterm); /* 5-tuple */
+	alloc_sz += ERTS_MAX_SINT64_HEAP_SIZE*sizeof(Eterm); /* max offset size */
+	tmp = erts_alloc(ERTS_ALC_T_TMP, alloc_sz);
+
+	to_mon_info = (ErtsTimeOffsetMonitorInfo *) tmp;
+	cntxt.ix = 0;
+	cntxt.to_mon_info = to_mon_info;
+
+	erts_doforall_monitors(time_offset_monitors,
+			       save_time_offset_monitor,
+			       &cntxt);
+
+	ASSERT(cntxt.ix == no_monitors);
+    }
+
+    erts_smp_mtx_unlock(&erts_get_time_mtx);
+
+    if (no_monitors) {
+	Eterm *hp, *patch_refp, new_offset_term, message_template;
+	Uint mix, hsz;
+
+	/* Make message template */
+
+	hp = (Eterm *) (tmp + no_monitors*sizeof(ErtsTimeOffsetMonitorInfo));
+
+	hsz = 6; /* 5-tuple */
+	hsz += REF_THING_SIZE;
+	hsz += ERTS_SINT64_HEAP_SIZE(new_offset);
+
+	if (IS_SSMALL(new_offset))
+	    new_offset_term = make_small(new_offset);
+	else
+	    new_offset_term = erts_sint64_to_big(new_offset, &hp);
+	message_template = TUPLE5(hp,
+				  am_CHANGE,
+				  THE_NON_VALUE, /* Patch point for ref */
+				  am_time_offset,
+				  am_clock_service,
+				  new_offset_term);
+	patch_refp = &hp[2];
+
+	ASSERT(*patch_refp == THE_NON_VALUE);
+
+	for (mix = 0; mix < no_monitors; mix++) {
+	    Process *rp = erts_proc_lookup(to_mon_info[mix].pid);
+	    if (rp) {
+		Eterm ref = to_mon_info[mix].ref;
+		ErtsProcLocks rp_locks = ERTS_PROC_LOCK_LINK;
+		erts_smp_proc_lock(rp, ERTS_PROC_LOCK_LINK);
+		if (erts_lookup_monitor(ERTS_P_MONITORS(rp), ref)) {
+		    ErlHeapFragment *bp;
+		    ErlOffHeap *ohp;
+		    Eterm message;
+
+		    hp = erts_alloc_message_heap(hsz, &bp, &ohp, rp, &rp_locks);
+		    *patch_refp = ref;
+		    ASSERT(hsz == size_object(message_template));
+		    message = copy_struct(message_template, hsz, &hp, ohp);
+		    erts_queue_message(rp, &rp_locks, bp, message, NIL
+#ifdef USE_VM_PROBES
+				       , NIL
+#endif
+			);
+		}
+		erts_smp_proc_unlock(rp, rp_locks);
+	    }
 	}
-	rem_time->tv_sec = (ticks - elapsed) / 1000;
-	rem_time->tv_usec = 1000 * ((ticks - elapsed) % 1000);
+
+	erts_free(ERTS_ALC_T_TMP, tmp);
     }
 }
 
-void erts_get_timeval(SysTimeval *tv)
+static void
+schedule_send_time_offset_changed_notifications(ErtsMonotonicTime new_offset)
 {
-    erts_smp_mtx_lock(&erts_timeofday_mtx);
-    get_tolerant_timeofday(tv);
-    erts_smp_mtx_unlock(&erts_timeofday_mtx);
-    update_approx_time(tv);
+#ifdef ARCH_64
+    void *new_offsetp = (void *) new_offset;
+    ASSERT(sizeof(void *) == sizeof(ErtsMonotonicTime));
+#else
+    void *new_offsetp = erts_alloc(ERTS_ALC_T_NEW_TIME_OFFSET,
+				   sizeof(ErtsMonotonicTime));
+    *((ErtsMonotonicTime *) new_offsetp) = new_offset;
+#endif
+    erts_schedule_misc_aux_work(1,
+				send_time_offset_changed_notifications,
+				new_offsetp);
 }
 
-erts_time_t
-erts_get_time(void)
+static ERTS_INLINE Eterm
+make_time_val(Process *c_p, ErtsMonotonicTime time_val)
 {
-    SysTimeval sys_tv;
-    
-    erts_smp_mtx_lock(&erts_timeofday_mtx);
-    
-    get_tolerant_timeofday(&sys_tv);
-    
-    erts_smp_mtx_unlock(&erts_timeofday_mtx);
+    Sint64 val = (Sint64) time_val;
+    Eterm *hp;
+    Uint sz;
 
-    update_approx_time(&sys_tv);
+    if (IS_SSMALL(val))
+	return make_small(val);
 
-    return sys_tv.tv_sec;
+    sz = ERTS_SINT64_HEAP_SIZE(val);
+    hp = HAlloc(c_p, sz);
+    return erts_sint64_to_big(val, &hp);
 }
 
-#ifdef HAVE_ERTS_NOW_CPU
-void erts_get_now_cpu(Uint* megasec, Uint* sec, Uint* microsec) {
-  SysCpuTime t;
-  SysTimespec tp;
+Eterm
+erts_get_monotonic_start_time(struct process *c_p)
+{
+    return make_time_val(c_p, ERTS_MONOTONIC_OFFSET_NATIVE);
+}
 
-  sys_get_proc_cputime(t, tp);
-  *microsec = (Uint)(tp.tv_nsec / 1000);
-  t = (tp.tv_sec / 1000000);
-  *megasec = (Uint)(t % 1000000);
-  *sec = (Uint)(tp.tv_sec % 1000000);
+static Eterm
+bld_monotonic_time_source(Uint **hpp, Uint *szp, Sint64 os_mtime)
+{
+#ifndef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+    return NIL;
+#else
+    int i = 0;
+    Eterm k[5];
+    Eterm v[5];
+
+    if (time_sup.r.o.os_monotonic_disable)
+	return NIL;
+
+    k[i] = erts_bld_atom(hpp, szp, "function");
+    v[i++] = erts_bld_atom(hpp, szp, time_sup.r.o.os_monotonic_func);
+
+    if (time_sup.r.o.os_monotonic_clock_id) {
+	k[i] = erts_bld_atom(hpp, szp, "clock_id");
+	v[i++] = erts_bld_atom(hpp, szp, time_sup.r.o.os_monotonic_clock_id);
+    }
+
+    if (time_sup.r.o.os_monotonic_resolution) {
+	k[i] = erts_bld_atom(hpp, szp, "resolution");
+	v[i++] = erts_bld_uint64(hpp, szp, time_sup.r.o.os_monotonic_resolution);
+    }
+
+    k[i] = erts_bld_atom(hpp, szp, "parallel");
+    v[i++] = time_sup.r.o.os_monotonic_locked ? am_no : am_yes;
+
+    k[i] = erts_bld_atom(hpp, szp, "time");
+    v[i++] = erts_bld_sint64(hpp, szp, os_mtime);
+
+    return erts_bld_2tup_list(hpp, szp, (Sint) i, k, v);
+#endif
 }
+
+Eterm
+erts_monotonic_time_source(struct process *c_p)
+{
+    Uint hsz = 0;
+    Eterm *hp = NULL;
+    Sint64 os_mtime = 0;
+#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+    if (!time_sup.r.o.os_monotonic_disable)
+	os_mtime = (Sint64) erts_os_monotonic_time();
+#endif
+
+    bld_monotonic_time_source(NULL, &hsz, os_mtime);
+    if (hsz)
+	hp = HAlloc(c_p, hsz);
+    return bld_monotonic_time_source(&hp, NULL, os_mtime);
+}
+
+
+#include "bif.h"
+
+static ERTS_INLINE Eterm
+time_unit_conversion(Process *c_p, Eterm term, ErtsMonotonicTime val, ErtsMonotonicTime muloff)
+{
+    ErtsMonotonicTime result;
+    BIF_RETTYPE ret;
+
+    if (val < 0)
+	goto trap_to_erlang_code;
+
+    /* Convert to common user specified time units */
+    switch (term) {
+    case am_seconds:
+    case make_small(1):
+	result = ERTS_MONOTONIC_TO_SEC(val) + muloff*ERTS_MONOTONIC_OFFSET_SEC;
+	ERTS_BIF_PREP_RET(ret, make_time_val(c_p, result));
+	break;
+    case am_milli_seconds:
+    case make_small(1000):
+	result = ERTS_MONOTONIC_TO_MSEC(val) + muloff*ERTS_MONOTONIC_OFFSET_MSEC;
+	ERTS_BIF_PREP_RET(ret, make_time_val(c_p, result));
+	break;
+    case am_micro_seconds:
+    case make_small(1000*1000):
+	result = ERTS_MONOTONIC_TO_USEC(val) + muloff*ERTS_MONOTONIC_OFFSET_USEC;
+	ERTS_BIF_PREP_RET(ret, make_time_val(c_p, result));
+	break;
+#ifdef ARCH_64
+    case am_nano_seconds:
+    case make_small(1000*1000*1000):
+	result = ERTS_MONOTONIC_TO_NSEC(val) + muloff*ERTS_MONOTONIC_OFFSET_NSEC;
+	ERTS_BIF_PREP_RET(ret, make_time_val(c_p, result));
+	break;
 #endif
+    default: {
+	Eterm value, native_res;
+#ifndef ARCH_64
+	Sint user_res;
+	if (term == am_nano_seconds)
+	    goto to_nano_seconds;
+	if (term_to_Sint(term, &user_res)) {
+	    if (user_res == 1000*1000*1000) {
+	    to_nano_seconds:
+		result = (ERTS_MONOTONIC_TO_NSEC(val)
+			  + muloff*ERTS_MONOTONIC_OFFSET_NSEC);
+		ERTS_BIF_PREP_RET(ret, make_time_val(c_p, result));
+		break;
+	    }
+	    if (user_res <= 0)
+		goto badarg;
+	}
+#else
+	if (is_small(term)) {
+	    if (signed_val(term) <= 0)
+		goto badarg;
+	}
+#endif
+	else if (is_big(term)) {
+	    if (big_sign(term))
+		goto badarg;
+	}
+	else {
+	badarg:
+	    ERTS_BIF_PREP_ERROR(ret, c_p, BADARG);
+	    break;
+	}
+
+	trap_to_erlang_code:
+	/* Do it in erlang code instead; pass along values to use... */
+	value = make_time_val(c_p, val + muloff*ERTS_MONOTONIC_OFFSET_NATIVE);
+	native_res = make_time_val(c_p, ERTS_MONOTONIC_TIME_UNIT);
+
+	ERTS_BIF_PREP_TRAP3(ret, erts_convert_time_unit_trap, c_p,
+			    value, native_res, term);
+
+	break;
+    }
+    }
+
+    return ret;
+}
+
+/* Built in functions */
+
+BIF_RETTYPE monotonic_time_0(BIF_ALIST_0)
+{
+    ErtsMonotonicTime mtime = time_sup.r.o.get_time();
+    mtime += ERTS_MONOTONIC_OFFSET_NATIVE;
+    BIF_RET(make_time_val(BIF_P, mtime));
+}
+
+BIF_RETTYPE monotonic_time_1(BIF_ALIST_1)
+{
+    BIF_RET(time_unit_conversion(BIF_P, BIF_ARG_1, time_sup.r.o.get_time(), 1));
+}
+
+BIF_RETTYPE system_time_0(BIF_ALIST_0)
+{
+    ErtsMonotonicTime mtime, offset;
+    mtime = time_sup.r.o.get_time();
+    offset = get_time_offset();
+    BIF_RET(make_time_val(BIF_P, mtime + offset));
+}
+
+BIF_RETTYPE system_time_1(BIF_ALIST_0)
+{
+    ErtsMonotonicTime mtime, offset;
+    mtime = time_sup.r.o.get_time();
+    offset = get_time_offset();
+    BIF_RET(time_unit_conversion(BIF_P, BIF_ARG_1, mtime + offset, 0));
+}
+
+BIF_RETTYPE erts_internal_time_unit_0(BIF_ALIST_0)
+{
+    BIF_RET(make_time_val(BIF_P, ERTS_MONOTONIC_TIME_UNIT));
+}
+
+BIF_RETTYPE time_offset_0(BIF_ALIST_0)
+{
+    ErtsMonotonicTime time_offset = get_time_offset();
+    time_offset -= ERTS_MONOTONIC_OFFSET_NATIVE;
+    BIF_RET(make_time_val(BIF_P, time_offset));
+}
+
+BIF_RETTYPE time_offset_1(BIF_ALIST_1)
+{
+    BIF_RET(time_unit_conversion(BIF_P, BIF_ARG_1, get_time_offset(), -1));
+}
+
+
+BIF_RETTYPE timestamp_0(BIF_ALIST_0)
+{
+    Eterm *hp, res;
+    ErtsMonotonicTime stime, mtime, all_sec, offset;
+    Uint mega_sec, sec, micro_sec;
+
+    mtime = time_sup.r.o.get_time();
+    offset = get_time_offset();
+    stime = ERTS_MONOTONIC_TO_USEC(mtime + offset);
+    all_sec = stime / ERTS_MONOTONIC_TIME_MEGA;
+    mega_sec = (Uint) (stime / ERTS_MONOTONIC_TIME_TERA);
+    sec = (Uint) (all_sec - (((ErtsMonotonicTime) mega_sec)
+			     * ERTS_MONOTONIC_TIME_MEGA));
+    micro_sec = (Uint) (stime - all_sec*ERTS_MONOTONIC_TIME_MEGA);
+
+    ASSERT(((ErtsMonotonicTime) mega_sec)*ERTS_MONOTONIC_TIME_TERA
+	   + ((ErtsMonotonicTime) sec)*ERTS_MONOTONIC_TIME_MEGA
+	   + micro_sec == stime);
+
+    /*
+     * Mega seconds is the only value that potentially
+     * ever could be a bignum. However, that wont happen
+     * during at least the next 4 million years...
+     *
+     * (System time will also have wrapped in the
+     * 64-bit integer before we get there...)
+     */
+
+    ASSERT(IS_USMALL(0, mega_sec));
+    ASSERT(IS_USMALL(0, sec));
+    ASSERT(IS_USMALL(0, micro_sec));
+
+    hp = HAlloc(BIF_P, 4);
+    res = TUPLE3(hp,
+		 make_small(mega_sec),
+		 make_small(sec),
+		 make_small(micro_sec));
+    BIF_RET(res);
+}
+
+BIF_RETTYPE os_system_time_0(BIF_ALIST_0)
+{
+    ErtsMonotonicTime stime;
+    SysTimeval tod;
+    sys_gettimeofday(&tod);
+    stime = ERTS_SEC_TO_MONOTONIC(tod.tv_sec);
+    stime += ERTS_USEC_TO_MONOTONIC(tod.tv_usec);
+    BIF_RET(make_time_val(BIF_P, stime));
+}
+
+BIF_RETTYPE os_system_time_1(BIF_ALIST_0)
+{
+    ErtsMonotonicTime stime;
+    SysTimeval tod;
+    sys_gettimeofday(&tod);
+    stime = ERTS_SEC_TO_MONOTONIC(tod.tv_sec);
+    stime += ERTS_USEC_TO_MONOTONIC(tod.tv_usec);
+    BIF_RET(time_unit_conversion(BIF_P, BIF_ARG_1, stime, 0));
+}
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index 891046a8b5..e24aef3e3c 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -346,8 +346,6 @@ extern Uint display_items;	/* no of items to display in traces etc */
 extern int erts_backtrace_depth;
 extern erts_smp_atomic32_t erts_max_gen_gcs;
 
-extern int erts_disable_tolerant_timeofday;
-
 extern int bif_reductions;      /* reductions + fcalls (when doing call_bif) */
 extern int stackdump_on_exit;
 
@@ -622,9 +620,6 @@ erts_bld_port_info(Eterm **hpp,
 void erts_bif_info_init(void);
 
 /* bif.c */
-Eterm erts_make_ref(Process *);
-Eterm erts_make_ref_in_buffer(Eterm buffer[REF_THING_SIZE]);
-void erts_make_ref_in_array(Uint32 ref[ERTS_MAX_REF_NUMBERS]);
 
 ERTS_GLB_INLINE Eterm
 erts_proc_store_ref(Process *c_p, Uint32 ref[ERTS_MAX_REF_NUMBERS]);
diff --git a/erts/emulator/beam/io.c b/erts/emulator/beam/io.c
index 9ae973e108..c0e44b239b 100644
--- a/erts/emulator/beam/io.c
+++ b/erts/emulator/beam/io.c
@@ -47,6 +47,7 @@
 #include "external.h"
 #include "dtrace-wrapper.h"
 #include "erl_map.h"
+#include "erl_bif_unique.h"
 
 extern ErlDrvEntry fd_driver_entry;
 #ifndef __OSE__
diff --git a/erts/emulator/beam/sys.h b/erts/emulator/beam/sys.h
index c29d4b3777..7e64623686 100644
--- a/erts/emulator/beam/sys.h
+++ b/erts/emulator/beam/sys.h
@@ -21,6 +21,25 @@
 #define __SYS_H__
 
 
+#if defined(DEBUG) || defined(ERTS_ENABLE_LOCK_CHECK)
+#  undef ERTS_CAN_INLINE
+#  define ERTS_CAN_INLINE 0
+#  undef ERTS_INLINE
+#  define ERTS_INLINE
+#endif
+
+#if ERTS_CAN_INLINE
+#define ERTS_GLB_INLINE static ERTS_INLINE
+#else
+#define ERTS_GLB_INLINE
+#endif
+
+#if ERTS_CAN_INLINE || defined(ERTS_DO_INCL_GLB_INLINE_FUNC_DEF) 
+#  define ERTS_GLB_INLINE_INCL_FUNC_DEF 1
+#else
+#  define ERTS_GLB_INLINE_INCL_FUNC_DEF 0
+#endif
+
 #if defined(VALGRIND) && !defined(NO_FPE_SIGNALS)
 #  define NO_FPE_SIGNALS
 #endif
@@ -132,24 +151,8 @@ typedef ERTS_SYS_FD_TYPE ErtsSysFdType;
 #  endif
 #endif
 
-#if defined(DEBUG) || defined(ERTS_ENABLE_LOCK_CHECK)
-#  undef ERTS_CAN_INLINE
-#  define ERTS_CAN_INLINE 0
-#  undef ERTS_INLINE
-#  define ERTS_INLINE
-#endif
-
-#if ERTS_CAN_INLINE
-#define ERTS_GLB_INLINE static ERTS_INLINE
-#else
-#define ERTS_GLB_INLINE
-#endif
-
-#if ERTS_CAN_INLINE || defined(ERTS_DO_INCL_GLB_INLINE_FUNC_DEF) 
-#  define ERTS_GLB_INLINE_INCL_FUNC_DEF 1
-#else
-#  define ERTS_GLB_INLINE_INCL_FUNC_DEF 0
-#endif
+#define ERTS_MK_VSN_INT(Major, Minor, Build) \
+    ((((Major) & 0x3ff) << 20) | (((Minor) & 0x3ff) << 10) | ((Build) & 0x3ff))
 
 #ifndef ERTS_EXIT_AFTER_DUMP
 #  define ERTS_EXIT_AFTER_DUMP exit
@@ -359,17 +362,45 @@ typedef Sint SWord;
 typedef UWord BeamInstr;
 
 #ifndef HAVE_INT64
-#if SIZEOF_LONG == 8
-#define HAVE_INT64 1
+#  if SIZEOF_LONG == 8
+#    define HAVE_INT64 1
 typedef unsigned long Uint64;
 typedef long          Sint64;
-#elif SIZEOF_LONG_LONG == 8
-#define HAVE_INT64 1
+#    ifdef ULONG_MAX
+#      define ERTS_UINT64_MAX ULONG_MAX
+#    endif
+#    ifdef LONG_MAX
+#      define ERTS_SINT64_MAX LONG_MAX
+#    endif
+#    ifdef LONG_MIN
+#      define ERTS_SINT64_MIN LONG_MIN
+#    endif
+#  elif SIZEOF_LONG_LONG == 8
+#    define HAVE_INT64 1
 typedef unsigned long long Uint64;
 typedef long long          Sint64;
-#else
-#define HAVE_INT64 0
+#    ifdef ULLONG_MAX
+#      define ERTS_UINT64_MAX ULLONG_MAX
+#    endif
+#    ifdef LLONG_MAX
+#      define ERTS_SINT64_MAX LLONG_MAX
+#    endif
+#    ifdef LLONG_MIN
+#      define ERTS_SINT64_MIN LLONG_MIN
+#    endif
+#  else
+#    error "No 64-bit integer type found"
+#  endif
+#endif
+
+#ifndef ERTS_UINT64_MAX
+#  define ERTS_UINT64_MAX (~((Uint64) 0))
 #endif
+#ifndef ERTS_SINT64_MAX
+#  define ERTS_SINT64_MAX ((Sint64) ((((Uint64) 1) << 63)-1))
+#endif
+#ifndef ERTS_SINT64_MIN
+#  define ERTS_SINT64_MIN (-1*(((Sint64) 1) << 63))
 #endif
 
 #if SIZEOF_LONG == 4
@@ -646,10 +677,31 @@ extern char *erts_default_arg0;
 
 extern char os_type[];
 
-extern int sys_init_time(void);
+typedef enum {
+    ERTS_NO_TIME_WARP_MODE,
+    ERTS_SINGLE_TIME_WARP_MODE,
+    ERTS_MULTI_TIME_WARP_MODE
+} ErtsTimeWarpMode;
+
+typedef struct {
+    int have_os_monotonic;
+    ErtsMonotonicTime os_monotonic_time_unit;
+    ErtsMonotonicTime sys_clock_resolution;
+    struct {
+	Uint64 resolution;
+	char *func;
+	char *clock_id;
+	int locked_use;
+    } os_monotonic_info;
+} ErtsSysInitTimeResult;
+
+#define ERTS_SYS_INIT_TIME_RESULT_INITER \
+    {0, (ErtsMonotonicTime) -1, (ErtsMonotonicTime) 1}
+
+extern void sys_init_time(ErtsSysInitTimeResult *);
 extern void erts_deliver_time(void);
 extern void erts_time_remaining(SysTimeval *);
-extern int erts_init_time_sup(void);
+extern int erts_init_time_sup(int, ErtsTimeWarpMode);
 extern void erts_sys_init_float(void);
 extern void erts_thread_init_float(void);
 extern void erts_thread_disable_fpe(void);
@@ -700,7 +752,7 @@ extern char *erts_sys_ddll_error(int code);
 
 void erts_sys_schedule_interrupt(int set);
 #ifdef ERTS_SMP
-void erts_sys_schedule_interrupt_timed(int set, erts_short_time_t msec);
+void erts_sys_schedule_interrupt_timed(int, ErtsMonotonicTime);
 void erts_sys_main_thread(void);
 #endif
 
@@ -739,6 +791,7 @@ int univ_to_local(
 int local_to_univ(Sint *year, Sint *month, Sint *day, 
 		  Sint *hour, Sint *minute, Sint *second, int isdst);
 void get_now(Uint*, Uint*, Uint*);
+ErtsMonotonicTime erts_get_monotonic_time(void);
 void get_sys_now(Uint*, Uint*, Uint*);
 void set_break_quit(void (*)(void), void (*)(void));
 
diff --git a/erts/emulator/beam/time.c b/erts/emulator/beam/time.c
index 2fd8e0cf00..c9f8b68bca 100644
--- a/erts/emulator/beam/time.c
+++ b/erts/emulator/beam/time.c
@@ -83,6 +83,10 @@
 #define ASSERT_NO_LOCKED_LOCKS
 #endif
 
+#define ERTS_MONOTONIC_DAY ERTS_SEC_TO_MONOTONIC(60*60*24)
+#define ERTS_CLKTCKS_DAY ERTS_MONOTONIC_TO_CLKTCKS(ERTS_MONOTONIC_DAY)
+
+static erts_smp_atomic32_t is_bumping;
 static erts_smp_mtx_t tiw_lock;
 
 
@@ -91,18 +95,20 @@ static erts_smp_mtx_t tiw_lock;
 ** The individual timer cells in tiw are also protected by the same mutex.
 */
 
+/* timing wheel size NEED to be a power of 2 */
 #ifdef SMALL_MEMORY
-#define TIW_SIZE 8192
+#define TIW_SIZE (1 << 13)
 #else
-#define TIW_SIZE 65536		/* timing wheel size (should be a power of 2) */
+#define TIW_SIZE (1 << 20)
 #endif
 static ErlTimer** tiw;		/* the timing wheel, allocated in init_time() */
-static Uint tiw_pos;		/* current position in wheel */
+static ErtsMonotonicTime tiw_pos; /* current position in wheel */
 static Uint tiw_nto;		/* number of timeouts in wheel */
-static Uint tiw_min;
-static ErlTimer *tiw_min_ptr;
-
-/* END tiw_lock protected variables */
+static struct {
+    ErlTimer *head;
+    ErlTimer **tail;
+    Uint nto;
+} tiw_at_once;
 
 /* Actual interval time chosen by sys_init_time() */
 
@@ -114,77 +120,97 @@ static int tiw_itime; /* Constant after init */
 #  define TIW_ITIME tiw_itime
 #endif
 
-erts_smp_atomic32_t do_time;	/* set at clock interrupt */
-static ERTS_INLINE erts_short_time_t do_time_read(void)
-{
-    return erts_smp_atomic32_read_acqb(&do_time);
-}
+static int true_next_timeout_time;
+static ErtsMonotonicTime next_timeout_time;
+erts_atomic64_t erts_next_timeout__;
 
-static ERTS_INLINE erts_short_time_t do_time_update(void)
+static ERTS_INLINE void
+init_next_timeout(ErtsMonotonicTime time)
 {
-    return do_time_read();
+    erts_atomic64_init_nob(&erts_next_timeout__,
+			   (erts_aint64_t) time);
 }
 
-static ERTS_INLINE void do_time_init(void)
+static ERTS_INLINE void
+set_next_timeout(ErtsMonotonicTime time, int true_timeout)
 {
-    erts_smp_atomic32_init_nob(&do_time, 0);
+    true_next_timeout_time = true_timeout;
+    next_timeout_time = time;
+    erts_atomic64_set_relb(&erts_next_timeout__,
+			   (erts_aint64_t) time);
 }
 
 /* get the time (in units of TIW_ITIME) to the next timeout,
    or -1 if there are no timeouts                     */
 
-static erts_short_time_t next_time_internal(void) /* PRE: tiw_lock taken by caller */
+static ERTS_INLINE ErtsMonotonicTime
+find_next_timeout(ErtsMonotonicTime curr_time,
+		  ErtsMonotonicTime max_search_time)
 {
-    int i, tm, nto;
-    Uint32 min;
-    ErlTimer* p;
-    erts_short_time_t dt;
-  
-    if (tiw_nto == 0)
-	return -1;	/* no timeouts in wheel */
+    int start_ix, tiw_pos_ix;
+    ErlTimer *p;
+    int true_min_timeout;
+    ErtsMonotonicTime min_timeout, min_timeout_pos, slot_timeout_pos, timeout_limit;
 
-    if (tiw_min_ptr) {
-	min = tiw_min;
-	dt  = do_time_read();
-	return ((min >= dt) ? (min - dt) : 0);
+    ERTS_SMP_LC_ASSERT(erts_smp_lc_mtx_is_locked(&tiw_lock));
+
+    if (true_next_timeout_time)
+	return next_timeout_time;
+
+    /* We never set next timeout beyond timeout_limit */
+    timeout_limit = curr_time + ERTS_MONOTONIC_DAY;
+
+    if (tiw_nto == 0) { /* no timeouts in wheel */
+	true_min_timeout = true_next_timeout_time = 0;
+	min_timeout_pos = ERTS_MONOTONIC_TO_CLKTCKS(timeout_limit);
+	goto found_next;
     }
-  
-    /* start going through wheel to find next timeout */
-    tm = nto = 0;
-    min = (Uint32) -1;	/* max Uint32 */
-    i = tiw_pos;
+
+    /*
+     * Don't want others entering trying to bump
+     * timers while we are checking...
+     */
+    set_next_timeout(timeout_limit, 0);
+
+    true_min_timeout = 1;
+    slot_timeout_pos = tiw_pos;
+    min_timeout_pos = ERTS_MONOTONIC_TO_CLKTCKS(curr_time + max_search_time);
+
+    start_ix = tiw_pos_ix = (int) (tiw_pos & (TIW_SIZE-1));
+
     do {
-	p = tiw[i];
-	while (p != NULL) {
-	    nto++;
-	    if (p->count == 0) {
-		/* found next timeout */
-		dt = do_time_read();
-		/* p->count is zero */
-		tiw_min_ptr = p;
-		tiw_min     = tm;
-		return ((tm >= dt) ? (tm - dt) : 0);
-	    } else {
-		/* keep shortest time in 'min' */
-		if (tm + p->count*TIW_SIZE < min) {
-		    min = tm + p->count*TIW_SIZE;
-		    tiw_min_ptr = p;
-		    tiw_min     = min;
-		}
+	slot_timeout_pos++;
+	if (slot_timeout_pos >= min_timeout_pos) {
+	    true_min_timeout = 0;
+	    break;
+	}
+
+	p = tiw[tiw_pos_ix];
+
+	while (p) {
+	    ErtsMonotonicTime timeout_pos;
+	    ASSERT(p != p->next);
+	    timeout_pos = p->timeout_pos;
+	    if (min_timeout_pos > timeout_pos) {
+		min_timeout_pos = timeout_pos;
+		if (min_timeout_pos <= slot_timeout_pos)
+		    goto found_next;
 	    }
 	    p = p->next;
 	}
-	/* when we have found all timeouts the shortest time will be in min */
-	if (nto == tiw_nto) break;
-	tm++;
-	i = (i + 1) % TIW_SIZE;
-    } while (i != tiw_pos);
-    dt = do_time_read();
-    if (min <= (Uint32) dt)
-	return 0;
-    if ((min - (Uint32) dt) > (Uint32) ERTS_SHORT_TIME_T_MAX)
-	return ERTS_SHORT_TIME_T_MAX;
-    return (erts_short_time_t) (min - (Uint32) dt);
+
+	tiw_pos_ix++;
+	if (tiw_pos_ix == TIW_SIZE)
+	    tiw_pos_ix = 0;
+    } while (start_ix != tiw_pos_ix);
+
+found_next:
+
+    min_timeout = ERTS_CLKTCKS_TO_MONOTONIC(min_timeout_pos);
+    if (min_timeout != next_timeout_time)
+	set_next_timeout(min_timeout, true_min_timeout);
+
+    return min_timeout;
 }
 
 static void remove_timer(ErlTimer *p) {
@@ -212,72 +238,153 @@ static void remove_timer(ErlTimer *p) {
     tiw_nto--;
 }
 
-/* Private export to erl_time_sup.c */
-erts_short_time_t erts_next_time(void)
+ErtsMonotonicTime
+erts_check_next_timeout_time(ErtsMonotonicTime max_search_time)
 {
-    erts_short_time_t ret;
+    ErtsMonotonicTime next, curr;
+
+    curr = erts_get_monotonic_time();
 
     erts_smp_mtx_lock(&tiw_lock);
-    (void)do_time_update();
-    ret = next_time_internal();
+
+    next = find_next_timeout(curr, max_search_time);
+
     erts_smp_mtx_unlock(&tiw_lock);
-    return ret;
+
+    return next;
 }
 
-static ERTS_INLINE void bump_timer_internal(erts_short_time_t dt) /* PRE: tiw_lock is write-locked */
+#ifndef DEBUG
+#define ERTS_DBG_CHK_SAFE_TO_SKIP_TO(TO) ((void) 0)
+#else
+#define ERTS_DBG_CHK_SAFE_TO_SKIP_TO(TO) debug_check_safe_to_skip_to((TO))
+static void
+debug_check_safe_to_skip_to(ErtsMonotonicTime skip_to_pos)
 {
-    Uint keep_pos;
-    Uint count;
-    ErlTimer *p, **prev, *timeout_head, **timeout_tail;
-    Uint dtime = (Uint) dt;  
+    int slots, ix;
+    ErlTimer *tmr;
+    ErtsMonotonicTime tmp;
+
+    ix = (int) (tiw_pos & (TIW_SIZE-1));
+    tmp = skip_to_pos - tiw_pos;
+    ASSERT(tmp >= 0);
+    if (tmp < (ErtsMonotonicTime) TIW_SIZE)
+	slots = (int) tmp;
+    else
+	slots = TIW_SIZE;
+
+     while (slots > 0) {
+	tmr = tiw[ix];
+	while (tmr) {
+	    ASSERT(tmr->timeout_pos > skip_to_pos);
+	    tmr = tmr->next;
+	}
+	ix++;
+	if (ix == TIW_SIZE)
+	    ix = 0;
+	slots--;
+    }
+}
+#endif
+
+void erts_bump_timers(ErtsMonotonicTime curr_time)
+{
+    int tiw_pos_ix, slots;
+    ErlTimer *p, *timeout_head, **timeout_tail;
+    ErtsMonotonicTime bump_to, tmp_slots;
+
+    if (erts_smp_atomic32_cmpxchg_nob(&is_bumping, 1, 0) != 0)
+	return; /* Another thread is currently bumping... */
+
+    bump_to = ERTS_MONOTONIC_TO_CLKTCKS(curr_time);
+
+    erts_smp_mtx_lock(&tiw_lock);
+
+    if (tiw_pos >= bump_to) {
+	timeout_head = NULL;
+	goto done;
+    }
+
+    /* Don't want others here while we are bumping... */
+    set_next_timeout(curr_time + ERTS_MONOTONIC_DAY, 0);
+
+    if (!tiw_at_once.head) {
+	timeout_head = NULL;
+	timeout_tail = &timeout_head;
+    }
+    else {
+	ASSERT(tiw_nto >= tiw_at_once.nto);
+	timeout_head = tiw_at_once.head;
+	timeout_tail = tiw_at_once.tail;
+	tiw_nto -= tiw_at_once.nto;
+	tiw_at_once.head = NULL;
+	tiw_at_once.tail = &tiw_at_once.head;
+	tiw_at_once.nto = 0;
+    }
 
-    /* no need to bump the position if there aren't any timeouts */
     if (tiw_nto == 0) {
-	erts_smp_mtx_unlock(&tiw_lock);
-	return;
+	ERTS_DBG_CHK_SAFE_TO_SKIP_TO(bump_to);
+	tiw_pos = bump_to;
+	goto done;
     }
 
-    /* if do_time > TIW_SIZE we want to go around just once */
-    count = (Uint)(dtime / TIW_SIZE) + 1;
-    keep_pos = (tiw_pos + dtime) % TIW_SIZE;
-    if (dtime > TIW_SIZE) dtime = TIW_SIZE;
-  
-    timeout_head = NULL;
-    timeout_tail = &timeout_head;
-    while (dtime > 0) {
-	/* this is to decrease the counters with the right amount */
-	/* when dtime >= TIW_SIZE */
-	if (tiw_pos == keep_pos) count--;
-	prev = &tiw[tiw_pos];
-	while ((p = *prev) != NULL) {
-	    ASSERT( p != p->next);
-	    if (p->count < count) {     /* we have a timeout */
-		/* remove min time */
-		if (tiw_min_ptr == p) {
-		    tiw_min_ptr = NULL;
-		    tiw_min = 0;
-		}
+    if (true_next_timeout_time) {
+	ErtsMonotonicTime skip_until_pos;
+	/*
+	 * No need inspecting slots where we know no timeouts
+	 * to trigger should reside.
+	 */
 
+	skip_until_pos = ERTS_MONOTONIC_TO_CLKTCKS(next_timeout_time);
+	if (skip_until_pos > bump_to)
+	    skip_until_pos = bump_to;
+
+	ERTS_DBG_CHK_SAFE_TO_SKIP_TO(skip_until_pos);
+	ASSERT(skip_until_pos > tiw_pos);
+
+	tiw_pos = skip_until_pos - 1;
+    }
+
+    tiw_pos_ix = (int) ((tiw_pos+1) & (TIW_SIZE-1));
+    tmp_slots = (bump_to - tiw_pos);
+    if (tmp_slots < (ErtsMonotonicTime) TIW_SIZE)
+	slots = (int) tmp_slots;
+    else
+	slots = TIW_SIZE;
+ 
+    while (slots > 0) {
+	p = tiw[tiw_pos_ix];
+	while (p) {
+	    ErlTimer *next = p->next;
+	    ASSERT(p != next);
+	    if (p->timeout_pos <= bump_to) { /* we have a timeout */
 		/* Remove from list */
 		remove_timer(p);
 		*timeout_tail = p;	/* Insert in timeout queue */
 		timeout_tail = &p->next;
 	    }
-	    else {
-		/* no timeout, just decrease counter */
-		p->count -= count;
-		prev = &p->next;
-	    }
+	    p = next;
 	}
-	tiw_pos = (tiw_pos + 1) % TIW_SIZE;
-	dtime--;
+	tiw_pos_ix++;
+	if (tiw_pos_ix == TIW_SIZE)
+	    tiw_pos_ix = 0;
+	slots--;
     }
-    tiw_pos = keep_pos;
-    if (tiw_min_ptr)
-	tiw_min -= dt;
-    
+
+    ASSERT(tmp_slots >= (ErtsMonotonicTime) TIW_SIZE
+	   || tiw_pos_ix == (int) ((bump_to+1) & (TIW_SIZE-1)));
+
+    tiw_pos = bump_to;
+
+    /* Search at most two seconds ahead... */
+    (void) find_next_timeout(curr_time, ERTS_SEC_TO_MONOTONIC(2));
+
+done:
+
     erts_smp_mtx_unlock(&tiw_lock);
     
+    erts_smp_atomic32_set_nob(&is_bumping, 0);
+
     /* Call timedout timers callbacks */
     while (timeout_head) {
 	p = timeout_head;
@@ -288,6 +395,7 @@ static ERTS_INLINE void bump_timer_internal(erts_short_time_t dt) /* PRE: tiw_lo
 	 * accesses any field until the ->timeout
 	 * callback is called.
 	 */
+	ASSERT(p->timeout_pos <= bump_to);
 	p->next = NULL;
 	p->prev = NULL;
 	p->slot = 0;
@@ -295,12 +403,6 @@ static ERTS_INLINE void bump_timer_internal(erts_short_time_t dt) /* PRE: tiw_lo
     }
 }
 
-void erts_bump_timer(erts_short_time_t dt) /* dt is value from do_time */
-{
-    erts_smp_mtx_lock(&tiw_lock);
-    bump_timer_internal(dt);
-}
-
 Uint
 erts_timer_wheel_memory_size(void)
 {
@@ -310,13 +412,14 @@ erts_timer_wheel_memory_size(void)
 /* this routine links the time cells into a free list at the start
    and sets the time queue as empty */
 void
-erts_init_time(void)
+erts_init_time(int time_correction, ErtsTimeWarpMode time_warp_mode)
 {
+    ErtsMonotonicTime mtime;
     int i, itime;
 
     /* system dependent init; must be done before do_time_init()
        if timer thread is enabled */
-    itime = erts_init_time_sup();
+    itime = erts_init_time_sup(time_correction, time_warp_mode);
 #ifdef TIW_ITIME_IS_CONSTANT 
     if (itime != TIW_ITIME) {
 	erl_exit(ERTS_ABORT_EXIT, "timer resolution mismatch %d != %d", itime, TIW_ITIME);
@@ -325,16 +428,23 @@ erts_init_time(void)
     tiw_itime = itime;
 #endif
 
+    erts_smp_atomic32_init_nob(&is_bumping, 0);
     erts_smp_mtx_init(&tiw_lock, "timer_wheel");
 
     tiw = (ErlTimer**) erts_alloc(ERTS_ALC_T_TIMER_WHEEL,
 				  TIW_SIZE * sizeof(ErlTimer*));
     for(i = 0; i < TIW_SIZE; i++)
 	tiw[i] = NULL;
-    do_time_init();
-    tiw_pos = tiw_nto = 0;
-    tiw_min_ptr = NULL;
-    tiw_min = 0;
+
+    mtime = erts_get_monotonic_time();
+    tiw_pos = ERTS_MONOTONIC_TO_CLKTCKS(mtime);
+    tiw_nto = 0;
+    tiw_at_once.head = NULL;
+    tiw_at_once.tail = &tiw_at_once.head;
+    tiw_at_once.nto = 0;
+    init_next_timeout(mtime + ERTS_MONOTONIC_DAY);
+
+    erts_late_init_time_sup();
 }
 
 
@@ -343,58 +453,62 @@ erts_init_time(void)
 /*
 ** Insert a process into the time queue, with a timeout 't'
 */
-static void
-insert_timer(ErlTimer* p, Uint t)
+static ErtsMonotonicTime
+insert_timer(ErlTimer* p, ErtsMonotonicTime curr_time, ErtsMonotonicTime to)
 {
-    Uint tm;
-    Uint64 ticks;
+    ErtsMonotonicTime timeout_time, timeout_pos;
 
-    /* The current slot (tiw_pos) in timing wheel is the next slot to be
-     * be processed. Hence no extra time tick is needed.
-     *
-     * (x + y - 1)/y is precisely the "number of bins" formula.
-     */
-    ticks = (t + (TIW_ITIME - 1)) / TIW_ITIME;
+    if (to == 0) {
+	timeout_pos = ERTS_MONOTONIC_TO_CLKTCKS(curr_time);
+	tiw_nto++;
+	tiw_at_once.nto++;
+	*tiw_at_once.tail = p;
+	p->next = NULL;
+	p->timeout_pos = timeout_pos;
+	timeout_time = ERTS_CLKTCKS_TO_MONOTONIC(timeout_pos);
+    }
+    else {
+	int tm;
+	ErtsMonotonicTime ticks;
 
-    /* 
-     * Ticks must be a Uint64, or the addition may overflow here,
-     * resulting in an incorrect value for p->count below.
-     */
-    ticks += do_time_update(); /* Add backlog of unprocessed time */
-    
-    /* calculate slot */
-    tm = (ticks + tiw_pos) % TIW_SIZE;
-    p->slot = (Uint) tm;
-    p->count = (Uint) (ticks / TIW_SIZE);
+	ticks = ERTS_MSEC_TO_CLKTCKS(to);
+	timeout_pos = ERTS_MONOTONIC_TO_CLKTCKS(curr_time - 1) + 1 + ticks;
+
+	/* calculate slot */
+	tm = (int) (timeout_pos & (TIW_SIZE-1));
+	p->slot = (Uint) tm;
   
-    /* insert at head of list at slot */
-    p->next = tiw[tm];
-    p->prev = NULL;
-    if (p->next != NULL)
-	p->next->prev = p;
-    tiw[tm] = p;
+	/* insert at head of list at slot */
+	p->next = tiw[tm];
+	p->prev = NULL;
+	if (p->next != NULL)
+	    p->next->prev = p;
+	tiw[tm] = p;
 
+	tiw_nto++;
 
-    /* insert min time */
-    if ((tiw_nto == 0) || ((tiw_min_ptr != NULL) && (ticks < tiw_min))) {
-	tiw_min = ticks;
-	tiw_min_ptr = p;
-    }
-    if ((tiw_min_ptr == p) && (ticks > tiw_min)) {
-	/* some other timer might be 'min' now */
-	tiw_min = 0;
-	tiw_min_ptr = NULL;
+	timeout_time = ERTS_CLKTCKS_TO_MONOTONIC(timeout_pos);
+	p->timeout_pos = timeout_pos;
+
+	ASSERT(ERTS_MSEC_TO_MONOTONIC(to) <= timeout_time - curr_time);
+	ASSERT(timeout_time - curr_time
+	       < ERTS_MSEC_TO_MONOTONIC(to) + ERTS_CLKTCKS_TO_MONOTONIC(1));
     }
 
-    tiw_nto++;
+    if (timeout_time < next_timeout_time)
+	set_next_timeout(timeout_time, 1);
+
+    return timeout_time;
 }
 
 void
 erts_set_timer(ErlTimer* p, ErlTimeoutProc timeout, ErlCancelProc cancel,
 	      void* arg, Uint t)
 {
-
-    erts_deliver_time();
+#ifdef ERTS_SMP
+    ErtsMonotonicTime timeout_time;
+#endif
+    ErtsMonotonicTime current_time = erts_get_monotonic_time();
     erts_smp_mtx_lock(&tiw_lock);
     if (p->active) { /* XXX assert ? */
 	erts_smp_mtx_unlock(&tiw_lock);
@@ -404,11 +518,15 @@ erts_set_timer(ErlTimer* p, ErlTimeoutProc timeout, ErlCancelProc cancel,
     p->cancel = cancel;
     p->arg = arg;
     p->active = 1;
-    insert_timer(p, t);
+#ifdef ERTS_SMP
+    timeout_time =
+#else
+	(void)
+#endif
+	insert_timer(p, current_time, (ErtsMonotonicTime) t);
     erts_smp_mtx_unlock(&tiw_lock);
 #if defined(ERTS_SMP)
-    if (t <= (Uint) ERTS_SHORT_TIME_T_MAX)
-	erts_sys_schedule_interrupt_timed(1, (erts_short_time_t) t);
+    erts_sys_schedule_interrupt_timed(1, timeout_time);
 #endif
 }
 
@@ -421,14 +539,8 @@ erts_cancel_timer(ErlTimer* p)
 	return;
     }
 
-    /* is it the 'min' timer, remove min */
-    if (p == tiw_min_ptr) {
-	tiw_min_ptr = NULL;
-	tiw_min     = 0;
-    }
-
     remove_timer(p);
-    p->slot = p->count = 0;
+    p->slot = 0;
 
     if (p->cancel != NULL) {
 	erts_smp_mtx_unlock(&tiw_lock);
@@ -447,8 +559,7 @@ erts_cancel_timer(ErlTimer* p)
 Uint
 erts_time_left(ErlTimer *p)
 {
-    Uint left;
-    erts_short_time_t dt;
+    ErtsMonotonicTime current_time, timeout_time;
 
     erts_smp_mtx_lock(&tiw_lock);
 
@@ -457,45 +568,43 @@ erts_time_left(ErlTimer *p)
 	return 0;
     }
 
-    if (p->slot < tiw_pos)
-	left = (p->count + 1) * TIW_SIZE + p->slot - tiw_pos;
-    else
-	left = p->count * TIW_SIZE + p->slot - tiw_pos;
-    dt = do_time_read();
-    if (left < dt)
-	left = 0;
-    else
-	left -= dt;
+    timeout_time = ERTS_CLKTCKS_TO_MONOTONIC(p->timeout_pos);
 
     erts_smp_mtx_unlock(&tiw_lock);
 
-    return (Uint) left * TIW_ITIME;
+    current_time = erts_get_monotonic_time();
+    if (timeout_time <= current_time)
+	return 0;
+    return (Uint) ERTS_MONOTONIC_TO_MSEC(timeout_time - current_time);
 }
 
 #ifdef DEBUG
 void erts_p_slpq(void)
 {
+    ErtsMonotonicTime current_time = erts_get_monotonic_time();
     int i;
     ErlTimer* p;
   
     erts_smp_mtx_lock(&tiw_lock);
 
     /* print the whole wheel, starting at the current position */
-    erts_printf("\ntiw_pos = %d tiw_nto %d\n", tiw_pos, tiw_nto);
+    erts_printf("\ncurrent time = %bps tiw_pos = %d tiw_nto %d\n",
+		current_time, tiw_pos, tiw_nto);
     i = tiw_pos;
     if (tiw[i] != NULL) {
 	erts_printf("%d:\n", i);
 	for(p = tiw[i]; p != NULL; p = p->next) {
-	    erts_printf(" (count %d, slot %d)\n",
-			p->count, p->slot);
+	    erts_printf(" (timeout time %bps, slot %d)\n",
+			ERTS_CLKTCKS_TO_MONOTONIC(p->timeout_pos),
+			p->slot);
 	}
     }
-    for(i = (i+1)%TIW_SIZE; i != tiw_pos; i = (i+1)%TIW_SIZE) {
+    for(i = ((i+1) & (TIW_SIZE-1)); i != (tiw_pos & (TIW_SIZE-1)); i = ((i+1) & (TIW_SIZE-1))) {
 	if (tiw[i] != NULL) {
 	    erts_printf("%d:\n", i);
 	    for(p = tiw[i]; p != NULL; p = p->next) {
-		erts_printf(" (count %d, slot %d)\n",
-			    p->count, p->slot);
+		erts_printf(" (timeout time %bps, slot %d)\n",
+			    ERTS_CLKTCKS_TO_MONOTONIC(p->timeout_pos), p->slot);
 	    }
 	}
     }
diff --git a/erts/emulator/beam/utils.c b/erts/emulator/beam/utils.c
index c505c44905..54f1a122c4 100644
--- a/erts/emulator/beam/utils.c
+++ b/erts/emulator/beam/utils.c
@@ -49,6 +49,7 @@
 #include "beam_bp.h"
 #include "erl_ptab.h"
 #include "erl_check_io.h"
+#include "erl_bif_unique.h"
 
 #undef M_TRIM_THRESHOLD
 #undef M_TOP_PAD
@@ -4353,8 +4354,8 @@ erts_smp_ensure_later_interval_acqb(erts_interval_t *icp, Uint64 ic)
  */
 Uint64 erts_timestamp_millis(void)
 {
-#ifdef HAVE_GETHRTIME
-    return (Uint64) (sys_gethrtime() / 1000000);
+#ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+    return ERTS_MONOTONIC_TO_MSEC(erts_os_monotonic_time());
 #else
     Uint64 res;
     SysTimeval tv;
diff --git a/erts/emulator/sys/common/erl_check_io.c b/erts/emulator/sys/common/erl_check_io.c
index 0051b45b31..705f36c34c 100644
--- a/erts/emulator/sys/common/erl_check_io.c
+++ b/erts/emulator/sys/common/erl_check_io.c
@@ -1590,9 +1590,9 @@ ERTS_CIO_EXPORT(erts_check_io_interrupt)(int set)
 
 void
 ERTS_CIO_EXPORT(erts_check_io_interrupt_timed)(int set,
-					       erts_short_time_t msec)
+					       ErtsMonotonicTime timeout_time)
 {
-    ERTS_CIO_POLL_INTR_TMD(pollset.ps, set, msec);
+    ERTS_CIO_POLL_INTR_TMD(pollset.ps, set, timeout_time);
 }
 
 void
@@ -1600,7 +1600,7 @@ ERTS_CIO_EXPORT(erts_check_io)(int do_wait)
 {
     ErtsPollResFd *pollres;
     int pollres_len;
-    SysTimeval wait_time;
+    ErtsMonotonicTime timeout_time;
     int poll_ret, i;
     erts_aint_t current_cio_time;
 
@@ -1612,12 +1612,9 @@ ERTS_CIO_EXPORT(erts_check_io)(int do_wait)
 #endif
 
     /* Figure out timeout value */
-    if (do_wait) {
-	erts_time_remaining(&wait_time);
-    } else {			/* poll only */
-	wait_time.tv_sec = 0;
-	wait_time.tv_usec = 0;
-    }
+    timeout_time = (do_wait
+		    ? erts_check_next_timeout_time(ERTS_SEC_TO_MONOTONIC(10*60))
+		    : ERTS_POLL_NO_TIMEOUT /* poll only */);
 
     /*
      * No need for an atomic inc op when incrementing
@@ -1640,14 +1637,12 @@ ERTS_CIO_EXPORT(erts_check_io)(int do_wait)
 
     erts_smp_atomic_set_nob(&pollset.in_poll_wait, 1);
 
-    poll_ret = ERTS_CIO_POLL_WAIT(pollset.ps, pollres, &pollres_len, &wait_time);
+    poll_ret = ERTS_CIO_POLL_WAIT(pollset.ps, pollres, &pollres_len, timeout_time);
 
 #ifdef ERTS_ENABLE_LOCK_CHECK
     erts_lc_check_exact(NULL, 0); /* No locks should be locked */
 #endif
 
-    erts_deliver_time(); /* sync the machine's idea of time */
-
 #ifdef ERTS_BREAK_REQUESTED
     if (ERTS_BREAK_REQUESTED)
 	erts_do_break_handling();
diff --git a/erts/emulator/sys/common/erl_check_io.h b/erts/emulator/sys/common/erl_check_io.h
index d01297d55c..71355965aa 100644
--- a/erts/emulator/sys/common/erl_check_io.h
+++ b/erts/emulator/sys/common/erl_check_io.h
@@ -47,8 +47,8 @@ void erts_check_io_async_sig_interrupt_nkp(void);
 #endif
 void erts_check_io_interrupt_kp(int);
 void erts_check_io_interrupt_nkp(int);
-void erts_check_io_interrupt_timed_kp(int, erts_short_time_t);
-void erts_check_io_interrupt_timed_nkp(int, erts_short_time_t);
+void erts_check_io_interrupt_timed_kp(int, ErtsMonotonicTime);
+void erts_check_io_interrupt_timed_nkp(int, ErtsMonotonicTime);
 void erts_check_io_kp(int);
 void erts_check_io_nkp(int);
 void erts_init_check_io_kp(void);
@@ -65,7 +65,7 @@ int erts_check_io_max_files(void);
 void erts_check_io_async_sig_interrupt(void);
 #endif
 void erts_check_io_interrupt(int);
-void erts_check_io_interrupt_timed(int, erts_short_time_t);
+void erts_check_io_interrupt_timed(int, ErtsMonotonicTime);
 void erts_check_io(int);
 void erts_init_check_io(void);
 
diff --git a/erts/emulator/sys/common/erl_poll.c b/erts/emulator/sys/common/erl_poll.c
index aa412a20c8..f4d4a85ca4 100644
--- a/erts/emulator/sys/common/erl_poll.c
+++ b/erts/emulator/sys/common/erl_poll.c
@@ -320,7 +320,7 @@ struct ErtsPollSet_ {
 #if defined(USE_THREADS) || ERTS_POLL_ASYNC_INTERRUPT_SUPPORT
     erts_atomic32_t wakeup_state;
 #endif
-    erts_smp_atomic32_t timeout;
+    erts_atomic64_t timeout_time;
 #ifdef ERTS_POLL_COUNT_AVOIDED_WAKEUPS
     erts_smp_atomic_t no_avoided_wakeups;
     erts_smp_atomic_t no_avoided_interrupts;
@@ -384,6 +384,26 @@ static void check_poll_status(ErtsPollSet ps);
 static void print_misc_debug_info(void);
 #endif
 
+static ERTS_INLINE void
+init_timeout_time(ErtsPollSet ps)
+{
+    erts_atomic64_init_nob(&ps->timeout_time,
+			   (erts_aint64_t) ERTS_MONOTONIC_TIME_MAX);
+}
+
+static ERTS_INLINE void
+set_timeout_time(ErtsPollSet ps, ErtsMonotonicTime time)
+{
+    erts_atomic64_set_relb(&ps->timeout_time,
+			   (erts_aint64_t) time);
+}
+
+static ERTS_INLINE ErtsMonotonicTime
+get_timeout_time(ErtsPollSet ps)
+{
+    return (ErtsMonotonicTime) erts_atomic64_read_acqb(&ps->timeout_time);
+}
+
 #define ERTS_POLL_NOT_WOKEN	0
 #define ERTS_POLL_WOKEN		-1
 #define ERTS_POLL_WOKEN_INTR	1
@@ -1993,44 +2013,153 @@ save_poll_result(ErtsPollSet ps, ErtsPollResFd pr[], int max_res,
     }
 }
 
+static ERTS_INLINE ErtsMonotonicTime
+get_timeout(ErtsPollSet ps,
+	    int resolution,
+	    ErtsMonotonicTime timeout_time)
+{
+    ErtsMonotonicTime timeout, save_timeout_time;
+
+    if (timeout_time == ERTS_POLL_NO_TIMEOUT) {
+	save_timeout_time = ERTS_MONOTONIC_TIME_MIN;
+	timeout = 0;
+    }
+    else {
+	ErtsMonotonicTime diff_time, current_time;
+	current_time = erts_get_monotonic_time();
+	diff_time = timeout_time - current_time;
+	if (diff_time <= 0) {
+	    save_timeout_time = ERTS_MONOTONIC_TIME_MIN;
+	    timeout = 0;
+	}
+	else {
+	    save_timeout_time = current_time;
+	    switch (resolution) {
+	    case 1000:
+		/* Round up to nearest even milli second */
+		timeout = ERTS_MONOTONIC_TO_MSEC(diff_time - 1) + 1;
+		if (timeout > (ErtsMonotonicTime) INT_MAX)
+		    timeout = (ErtsMonotonicTime) INT_MAX;
+		save_timeout_time += ERTS_MSEC_TO_MONOTONIC(timeout);
+		break;
+	    case 1000000:
+		/* Round up to nearest even micro second */
+		timeout = ERTS_MONOTONIC_TO_USEC(diff_time - 1) + 1;
+		save_timeout_time += ERTS_USEC_TO_MONOTONIC(timeout);
+		break;
+	    case 1000000000:
+		/* Round up to nearest even nano second */
+		timeout = ERTS_MONOTONIC_TO_NSEC(diff_time - 1) + 1;
+		save_timeout_time += ERTS_NSEC_TO_MONOTONIC(timeout);
+		break;
+	    default:
+		ERTS_INTERNAL_ERROR("Invalid resolution");
+		timeout = 0;
+		save_timeout_time = 0;
+		break;
+	    }
+	}
+    }
+    set_timeout_time(ps, save_timeout_time);
+    return timeout;
+}
+
+#if ERTS_POLL_USE_SELECT
+
 static ERTS_INLINE int
-check_fd_events(ErtsPollSet ps, SysTimeval *tv, int max_res)
+get_timeout_timeval(ErtsPollSet ps,
+		    SysTimeval *tvp,
+		    ErtsMonotonicTime timeout_time)
+{
+    ErtsMonotonicTime timeout = get_timeout(ps,
+					    1000*1000,
+					    timeout_time);
+
+    if (!timeout) {
+	tvp->tv_sec = 0;
+	tvp->tv_usec = 0;
+
+	return 0;
+    }
+    else {
+	ErtsMonotonicTime sec = timeout/(1000*1000);
+	tvp->tv_sec = sec;
+	tvp->tv_usec = timeout - sec*(1000*1000);
+
+	ASSERT(tvp->tv_sec >= 0);
+	ASSERT(tvp->tv_usec >= 0);
+	ASSERT(tvp->tv_usec < 1000*1000);
+
+	return !0;
+    }
+
+}
+
+#endif
+
+#if ERTS_POLL_USE_KQUEUE
+
+static ERTS_INLINE int
+get_timeout_timespec(ErtsPollSet ps,
+		     struct timespec *tsp,
+		     ErtsMonotonicTime timeout_time)
+{
+    ErtsMonotonicTime timeout = get_timeout(ps,
+					    1000*1000*1000,
+					    timeout_time);
+
+    if (!timeout) {
+	tsp->tv_sec = 0;
+	tsp->tv_nsec = 0;
+	return 0;
+    }
+    else {
+	ErtsMonotonicTime sec = timeout/(1000*1000*1000);
+	tsp->tv_sec = sec;
+	tsp->tv_nsec = timeout - sec*(1000*1000*1000);
+
+	ASSERT(tsp->tv_sec >= 0);
+	ASSERT(tsp->tv_nsec >= 0);
+	ASSERT(tsp->tv_nsec < 1000*1000);
+
+	return !0;
+    }
+}
+
+#endif
+
+static ERTS_INLINE int
+check_fd_events(ErtsPollSet ps, ErtsMonotonicTime timeout_time, int max_res)
 {
     int res;
     if (erts_smp_atomic_read_nob(&ps->no_of_user_fds) == 0
-	&& tv->tv_usec == 0 && tv->tv_sec == 0) {
+	&& timeout_time == ERTS_POLL_NO_TIMEOUT) {
 	/* Nothing to poll and zero timeout; done... */
 	return 0;
     }
     else {
-	long timeout = tv->tv_sec*1000 + tv->tv_usec/1000;
-	if (timeout > ERTS_AINT32_T_MAX)
-	    timeout = ERTS_AINT32_T_MAX;
-	ASSERT(timeout >= 0);
-	erts_smp_atomic32_set_relb(&ps->timeout, (erts_aint32_t) timeout);
+	int timeout;
 #if ERTS_POLL_USE_FALLBACK
 	if (!(ps->fallback_used = ERTS_POLL_NEED_FALLBACK(ps))) {
 
 #if ERTS_POLL_USE_EPOLL		/* --- epoll ------------------------------- */
-	    if (timeout > INT_MAX)
-		timeout = INT_MAX;
 	    if (max_res > ps->res_events_len)
 		grow_res_events(ps, max_res);
+	    timeout = (int) get_timeout(ps, 1000, timeout_time);
 #ifdef ERTS_SMP
 	    if (timeout)
 		erts_thr_progress_prepare_wait(NULL);
 #endif
-	    res = epoll_wait(ps->kp_fd, ps->res_events, max_res, (int)timeout);
+	    res = epoll_wait(ps->kp_fd, ps->res_events, max_res, timeout);
 #elif ERTS_POLL_USE_KQUEUE	/* --- kqueue ------------------------------ */
 	    struct timespec ts;
 	    if (max_res > ps->res_events_len)
 		grow_res_events(ps, max_res);
+	    timeout = get_timeout_timespec(ps, &ts, timeout_time);
 #ifdef ERTS_SMP
 	    if (timeout)
 		erts_thr_progress_prepare_wait(NULL);
 #endif
-	    ts.tv_sec = tv->tv_sec;
-	    ts.tv_nsec = tv->tv_usec*1000;
 	    res = kevent(ps->kp_fd, NULL, 0, ps->res_events, max_res, &ts);
 #endif				/* ----------------------------------------- */
 	}
@@ -2049,8 +2178,7 @@ check_fd_events(ErtsPollSet ps, SysTimeval *tv, int max_res)
 #if ERTS_POLL_USE_WAKEUP_PIPE
 	    nfds++; /* Wakeup pipe */
 #endif
-	    if (timeout > INT_MAX)
-		timeout = INT_MAX;
+	    timeout = (int) get_timeout(ps, 1000, timeout_time);
 	    poll_res.dp_nfds = nfds < max_res ? nfds : max_res;
 	    if (poll_res.dp_nfds > ps->res_events_len)
 		grow_res_events(ps, poll_res.dp_nfds);
@@ -2059,33 +2187,33 @@ check_fd_events(ErtsPollSet ps, SysTimeval *tv, int max_res)
 	    if (timeout)
 		erts_thr_progress_prepare_wait(NULL);
 #endif
-	    poll_res.dp_timeout = (int) timeout;
+	    poll_res.dp_timeout = timeout;
 	    res = ioctl(ps->kp_fd, DP_POLL, &poll_res);
 #elif ERTS_POLL_USE_POLL	/* --- poll -------------------------------- */
-	    if (timeout > INT_MAX)
-		timeout = INT_MAX;
+	    timeout = (int) get_timeout(ps, 1000, timeout_time);
 #ifdef ERTS_SMP
 	    if (timeout)
 		erts_thr_progress_prepare_wait(NULL);
 #endif
-	    res = poll(ps->poll_fds, ps->no_poll_fds, (int) timeout);
+	    res = poll(ps->poll_fds, ps->no_poll_fds, timeout);
 #elif ERTS_POLL_USE_SELECT	/* --- select ------------------------------ */
-	    SysTimeval to = *tv;
+	    SysTimeval to;
+	    timeout = get_timeout_timeval(ps, &to, timeout_time);
 
 	    ERTS_FD_COPY(&ps->input_fds, &ps->res_input_fds);
 	    ERTS_FD_COPY(&ps->output_fds, &ps->res_output_fds);
 	    
 #ifdef ERTS_SMP
-	    if (to.tv_sec || to.tv_usec)
+	    if (timeout)
 		erts_thr_progress_prepare_wait(NULL);
 #endif
 	    res = ERTS_SELECT(ps->max_fd + 1,
-			 &ps->res_input_fds,
-			 &ps->res_output_fds,
-			 NULL,
-			 &to);
+			      &ps->res_input_fds,
+			      &ps->res_output_fds,
+			      NULL,
+			      &to);
 #ifdef ERTS_SMP
-	    if (to.tv_sec || to.tv_usec)
+	    if (timeout)
 		erts_thr_progress_finalize_wait(NULL);
 	    if (res < 0
 		&& errno == EBADF
@@ -2108,10 +2236,10 @@ check_fd_events(ErtsPollSet ps, SysTimeval *tv, int max_res)
 		handle_update_requests(ps);
 		ERTS_POLLSET_UNLOCK(ps);
 		res = ERTS_SELECT(ps->max_fd + 1,
-			     &ps->res_input_fds,
-			     &ps->res_output_fds,
-			     NULL,
-			     &to);
+				  &ps->res_input_fds,
+				  &ps->res_output_fds,
+				  NULL,
+				  &to);
 		if (res == 0) {
 		    errno = EAGAIN;
 		    res = -1;
@@ -2133,15 +2261,14 @@ int
 ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet ps,
 				 ErtsPollResFd pr[],
 				 int *len,
-				 SysTimeval *utvp)
+				 ErtsMonotonicTime timeout_time)
 {
+    ErtsMonotonicTime to;
     int res, no_fds;
     int ebadf = 0;
 #ifdef ERTS_SMP
     int ps_locked = 0;
 #endif
-    SysTimeval *tvp;
-    SysTimeval itv;
 
     no_fds = *len;
 #ifdef ERTS_POLL_MAX_RES
@@ -2151,13 +2278,9 @@ ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet ps,
 
     *len = 0;
 
-    ASSERT(utvp);
-
-    tvp = utvp;
-
 #ifdef ERTS_POLL_DEBUG_PRINT
-    erts_printf("Entering erts_poll_wait(), timeout=%d\n",
-		 (int) tvp->tv_sec*1000 + tvp->tv_usec/1000);
+    erts_printf("Entering erts_poll_wait(), timeout_time=%bps\n",
+		timeout_time);
 #endif
 
     if (ERTS_POLLSET_SET_POLLED_CHK(ps)) {
@@ -2166,12 +2289,9 @@ ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet ps,
 	goto done;
     }
 
-    if (is_woken(ps)) {
-	/* Use zero timeout */
-	itv.tv_sec = 0;
-	itv.tv_usec = 0;
-	tvp = &itv;
-    }
+    to = (is_woken(ps)
+	  ? ERTS_POLL_NO_TIMEOUT /* Use zero timeout */
+	  : timeout_time);
 
 #if ERTS_POLL_USE_UPDATE_REQUESTS_QUEUE
     if (ERTS_POLLSET_HAVE_UPDATE_REQUESTS(ps)) {
@@ -2181,7 +2301,7 @@ ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet ps,
     }
 #endif
 
-    res = check_fd_events(ps, tvp, no_fds);
+    res = check_fd_events(ps, to, no_fds);
 
     woke_up(ps);
 
@@ -2224,7 +2344,7 @@ ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet ps,
 #endif
 
  done:
-    erts_smp_atomic32_set_relb(&ps->timeout, ERTS_AINT32_T_MAX);
+    set_timeout_time(ps, ERTS_MONOTONIC_TIME_MAX);
 #ifdef ERTS_POLL_DEBUG_PRINT
     erts_printf("Leaving %s = erts_poll_wait()\n",
 		 res == 0 ? "0" : erl_errno_id(res));
@@ -2268,13 +2388,14 @@ ERTS_POLL_EXPORT(erts_poll_async_sig_interrupt)(ErtsPollSet ps)
 void
 ERTS_POLL_EXPORT(erts_poll_interrupt_timed)(ErtsPollSet ps,
 					    int set,
-					    erts_short_time_t msec)
+					    ErtsMonotonicTime timeout_time)
 {
 #if ERTS_POLL_ASYNC_INTERRUPT_SUPPORT || defined(ERTS_SMP)
     if (!set)
 	reset_wakeup_state(ps);
     else {
-	if (erts_smp_atomic32_read_acqb(&ps->timeout) > (erts_aint32_t) msec)
+	ErtsMonotonicTime max_wait_time = get_timeout_time(ps);
+	if (max_wait_time > timeout_time)
 	    wake_poller(ps, 1, 0);
 #ifdef ERTS_POLL_COUNT_AVOIDED_WAKEUPS
 	else {
@@ -2431,7 +2552,7 @@ ERTS_POLL_EXPORT(erts_poll_create_pollset)(void)
 	ps->internal_fd_limit = kp_fd + 1;
     ps->kp_fd = kp_fd;
 #endif
-    erts_smp_atomic32_init_nob(&ps->timeout, ERTS_AINT32_T_MAX);
+    init_timeout_time(ps);
 #ifdef ERTS_POLL_COUNT_AVOIDED_WAKEUPS
     erts_smp_atomic_init_nob(&ps->no_avoided_wakeups, 0);
     erts_smp_atomic_init_nob(&ps->no_avoided_interrupts, 0);
diff --git a/erts/emulator/sys/common/erl_poll.h b/erts/emulator/sys/common/erl_poll.h
index 2f1c05f401..d02ed2396b 100644
--- a/erts/emulator/sys/common/erl_poll.h
+++ b/erts/emulator/sys/common/erl_poll.h
@@ -29,6 +29,8 @@
 
 #include "sys.h"
 
+#define ERTS_POLL_NO_TIMEOUT ERTS_MONOTONIC_TIME_MIN
+
 #if 0
 #define ERTS_POLL_COUNT_AVOIDED_WAKEUPS
 #endif
@@ -241,7 +243,7 @@ void		ERTS_POLL_EXPORT(erts_poll_interrupt)(ErtsPollSet,
 						      int);
 void		ERTS_POLL_EXPORT(erts_poll_interrupt_timed)(ErtsPollSet,
 							    int,
-							    erts_short_time_t);
+							    ErtsMonotonicTime);
 ErtsPollEvents	ERTS_POLL_EXPORT(erts_poll_control)(ErtsPollSet,
 						    ErtsSysFdType,
 						    ErtsPollEvents,
@@ -254,7 +256,7 @@ void		ERTS_POLL_EXPORT(erts_poll_controlv)(ErtsPollSet,
 int		ERTS_POLL_EXPORT(erts_poll_wait)(ErtsPollSet,
 						 ErtsPollResFd [],
 						 int *,
-						 SysTimeval *);
+						 ErtsMonotonicTime);
 int		ERTS_POLL_EXPORT(erts_poll_max_fds)(void);
 void		ERTS_POLL_EXPORT(erts_poll_info)(ErtsPollSet,
 						 ErtsPollInfo *);
diff --git a/erts/emulator/sys/ose/erl_poll.c b/erts/emulator/sys/ose/erl_poll.c
index 7d2a3d1e0b..36ee2557e8 100644
--- a/erts/emulator/sys/ose/erl_poll.c
+++ b/erts/emulator/sys/ose/erl_poll.c
@@ -114,7 +114,7 @@ struct ErtsPollSet_ {
     Uint item_count;
     PROCESS interrupt;
     erts_atomic32_t wakeup_state;
-    erts_smp_atomic32_t timeout;
+    erts_atomic64_t timeout_time;
 #ifdef ERTS_SMP
     erts_smp_mtx_t mtx;
 #endif
@@ -122,6 +122,26 @@ struct ErtsPollSet_ {
 
 static int max_fds = -1;
 
+static ERTS_INLINE void
+init_timeout_time(ErtsPollSet ps)
+{
+    erts_atomic64_init_nob(&ps->timeout_time,
+			   (erts_aint64_t) ERTS_MONOTONIC_TIME_MAX);
+}
+
+static ERTS_INLINE void
+set_timeout_time(ErtsPollSet ps, ErtsMonotonicTime time)
+{
+    erts_atomic64_set_relb(&ps->timeout_time,
+			   (erts_aint64_t) time);
+}
+
+static ERTS_INLINE ErtsMonotonicTime
+get_timeout_time(ErtsPollSet ps)
+{
+    return (ErtsMonotonicTime) erts_atomic64_read_acqb(&ps->timeout_time);
+}
+
 #define ERTS_POLL_NOT_WOKEN		((erts_aint32_t) (1 << 0))
 #define ERTS_POLL_WOKEN_INTR		((erts_aint32_t) (1 << 1))
 #define ERTS_POLL_WOKEN_TIMEDOUT	((erts_aint32_t) (1 << 2))
@@ -386,12 +406,14 @@ void erts_poll_interrupt(ErtsPollSet ps,int set) {
 
 }
 
-void erts_poll_interrupt_timed(ErtsPollSet ps,int set,erts_short_time_t msec) {
+void erts_poll_interrupt_timed(ErtsPollSet ps,
+			       int set,
+			       ErtsTimeoutTime timeout_time) {
     HARDTRACEF("erts_poll_interrupt_timed called!\n");
 
     if (!set)
 	reset_interrupt(ps);
-    else if (erts_smp_atomic32_read_acqb(&ps->timeout) > (erts_aint32_t) msec)
+    else if (get_timeout_time(ps) > timeout_time)
         set_interrupt(ps);
 }
 
@@ -453,12 +475,14 @@ done:
 }
 
 int erts_poll_wait(ErtsPollSet ps,
-	   ErtsPollResFd pr[],
-	   int *len,
-	   SysTimeval *utvp) {
+		   ErtsPollResFd pr[],
+		   int *len,
+		   ErtsMonotonicTime timeout_time)
+{
     int res = ETIMEDOUT, no_fds, currid = 0;
     OSTIME timeout;
     union SIGNAL *sig;
+    ErtsMonotonicTime current_time, diff_time, timeout;
     // HARDTRACEF("%ux: In erts_poll_wait",ps);
     if (ps->interrupt == (PROCESS)0)
       ps->interrupt = current_process();
@@ -472,16 +496,29 @@ int erts_poll_wait(ErtsPollSet ps,
 
     *len = 0;
 
-    ASSERT(utvp);
+    /* erts_printf("Entering erts_poll_wait(), timeout_time=%bps\n",
+		   timeout_time); */
 
-    /* erts_printf("Entering erts_poll_wait(), timeout=%d\n",
-		 (int) utvp->tv_sec*1000 + utvp->tv_usec/1000); */
-
-    timeout = utvp->tv_sec*1000 + utvp->tv_usec/1000;
+    if (timeout_time == ERTS_POLL_NO_TIMEOUT) {
+    no_timeout:
+	timeout = (OSTIME) 0;
+	save_timeout_time = ERTS_MONOTONIC_TIME_MIN;
+    }
+    else {
+	ErtsMonotonicTime current_time, diff_time;
+	current_time = erts_get_monotonic_time();
+	diff_time = timeout_time - current_time;
+	if (diff_time <= 0)
+	    goto no_timeout;
+	diff_time = (ERTS_MONOTONIC_TO_MSEC(diff_time - 1) + 1);
+	if (diff_time > INT_MAX)
+	    diff_time = INT_MAX;
+	timeout = (OSTIME) diff_time;
+	save_timeout_time = current_time;
+	save_timeout_time += ERTS_MSEC_TO_MONOTONIC(diff_time);
+    }
 
-    if (timeout > ((time_t) ERTS_AINT32_T_MAX))
-      timeout = ERTS_AINT32_T_MAX;
-    erts_smp_atomic32_set_relb(&ps->timeout, (erts_aint32_t) timeout);
+    set_timeout_time(ps, save_timeout_time);
 
     while (currid < no_fds) {
       if (timeout > 0) {
@@ -627,7 +664,7 @@ int erts_poll_wait(ErtsPollSet ps,
     }
 
     erts_atomic32_set_nob(&ps->wakeup_state, ERTS_POLL_NOT_WOKEN);
-    erts_smp_atomic32_set_nob(&ps->timeout, ERTS_AINT32_T_MAX);
+    set_timeout_time(ps, ERTS_MONOTONIC_TIME_MAX);
 
     *len = currid;
 
@@ -690,7 +727,7 @@ ErtsPollSet erts_poll_create_pollset(void)
     ps->info       = NULL;
     ps->interrupt  = (PROCESS)0;
     erts_atomic32_init_nob(&ps->wakeup_state, ERTS_POLL_NOT_WOKEN);
-    erts_smp_atomic32_init_nob(&ps->timeout, ERTS_AINT32_T_MAX);
+    init_timeout_time(ps);
 #ifdef ERTS_SMP
     erts_smp_mtx_init(&ps->mtx, "pollset");
 #endif
diff --git a/erts/emulator/sys/ose/sys.c b/erts/emulator/sys/ose/sys.c
index 5b950a7dae..13a5b71496 100644
--- a/erts/emulator/sys/ose/sys.c
+++ b/erts/emulator/sys/ose/sys.c
@@ -298,9 +298,9 @@ erts_sys_schedule_interrupt(int set)
 
 #ifdef ERTS_SMP
 void
-erts_sys_schedule_interrupt_timed(int set, erts_short_time_t msec)
+erts_sys_schedule_interrupt_timed(int set, ErtsMonotonicTime timeout_time)
 {
-    ERTS_CHK_IO_INTR_TMD(set, msec);
+    ERTS_CHK_IO_INTR_TMD(set, timeout_time);
 }
 #endif
 
diff --git a/erts/emulator/sys/unix/erl_unix_sys.h b/erts/emulator/sys/unix/erl_unix_sys.h
index 26ed2fb558..5417bb2687 100644
--- a/erts/emulator/sys/unix/erl_unix_sys.h
+++ b/erts/emulator/sys/unix/erl_unix_sys.h
@@ -114,11 +114,6 @@
 /*
  * Make sure that MAXPATHLEN is defined.
  */
-#ifdef GETHRTIME_WITH_CLOCK_GETTIME
-#undef HAVE_GETHRTIME
-#define HAVE_GETHRTIME 1
-#endif
-
 #ifndef MAXPATHLEN
 #   ifdef PATH_MAX
 #       define MAXPATHLEN PATH_MAX
@@ -160,33 +155,112 @@ typedef struct timeval SysTimeval;
 
 typedef struct tms SysTimes;
 
-extern int erts_ticks_per_sec;
-
-#define SYS_CLK_TCK (erts_ticks_per_sec)
+#define SYS_CLK_TCK (erts_sys_time_data__.r.o.ticks_per_sec)
 
 #define sys_times(Arg) times(Arg)
 
-#define ERTS_WRAP_SYS_TIMES 1
-extern int erts_ticks_per_sec_wrap;
-#define SYS_CLK_TCK_WRAP (erts_ticks_per_sec_wrap)
-extern clock_t sys_times_wrap(void);
+#if SIZEOF_LONG == 8
+typedef long ErtsMonotonicTime;
+#elif SIZEOF_LONG_LONG == 8
+typedef long long ErtsMonotonicTime;
+#else
+#error No signed 64-bit type found...
+#endif
+
+#define ERTS_MONOTONIC_TIME_MIN (((ErtsMonotonicTime) 1) << 63)
+#define ERTS_MONOTONIC_TIME_MAX (~ERTS_MONOTONIC_TIME_MIN)
+
+/*
+ * OS monotonic time
+ */
+
+/*
+ * Most common with os monotonic time using nano second
+ * time unit. These defines are modified below if this
+ * isn't the case...
+ */
+#define ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT 1
+#define ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT (1000*1000*1000)
+
+#undef ERTS_OS_MONOTONIC_INLINE_FUNC_PTR_CALL__
+#undef ERTS_HAVE_CORRECTED_OS_MONOTONIC
+
+#if defined(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME)
+
+#if defined(__linux__)
 
-#ifdef HAVE_GETHRTIME
-#ifdef GETHRTIME_WITH_CLOCK_GETTIME
-typedef long long SysHrTime;
+#define ERTS_HAVE_CORRECTED_OS_MONOTONIC 1
+#define ERTS_OS_MONOTONIC_INLINE_FUNC_PTR_CALL__ 1
 
-extern SysHrTime sys_gethrtime(void);
-#define sys_init_hrtime() /* Nothing */
+#else /* !defined(__linux__) */
 
-#else /* Real gethrtime (Solaris) */
+ErtsMonotonicTime erts_os_monotonic_time(void);
 
-typedef hrtime_t SysHrTime;
+#endif /* !defined(__linux__) */
+
+#elif defined(OS_MONOTONIC_TIME_USING_GETHRTIME)
+
+#define erts_os_monotonic() ((ErtsMonotonicTime) gethrtime())
+
+#elif defined(OS_MONOTONIC_TIME_USING_MACH_CLOCK_GET_TIME) \
+    || defined(OS_MONOTONIC_TIME_USING_TIMES)
+
+#if defined(OS_MONOTONIC_TIME_USING_TIMES)
+#  undef ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT
+#  define ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT (1000*1000)
+#  define ERTS_HAVE_ERTS_OS_TIME_OFFSET_FINALIZE 1
+void erts_os_time_offset_finalize(void);
+#  define ERTS_HAVE_ERTS_OS_MONOTONIC_TIME_INIT
+void erts_os_monotonic_time_init(void);
+#endif
 
-#define sys_gethrtime() gethrtime()
-#define sys_init_hrtime() /* Nothing */
+ErtsMonotonicTime erts_os_monotonic_time(void);
 
-#endif /* GETHRTIME_WITH_CLOCK_GETTIME */
-#endif /* HAVE_GETHRTIME */
+#else /* No OS monotonic available... */
+
+#undef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
+#undef ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT
+#define ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT (1000*1000)
+
+#endif
+
+struct erts_sys_time_read_only_data__ {
+#ifdef ERTS_OS_MONOTONIC_INLINE_FUNC_PTR_CALL__
+    ErtsMonotonicTime (*os_monotonic_time)(void);
+#endif
+    int ticks_per_sec;
+};
+
+typedef struct {
+    union {
+	struct erts_sys_time_read_only_data__ o;
+	char align__[(((sizeof(struct erts_sys_time_read_only_data__) - 1)
+		       / ASSUMED_CACHE_LINE_SIZE) + 1)
+		     * ASSUMED_CACHE_LINE_SIZE];
+    } r;
+} ErtsSysTimeData__;
+
+extern ErtsSysTimeData__ erts_sys_time_data__;
+
+#ifdef ERTS_OS_MONOTONIC_INLINE_FUNC_PTR_CALL__
+
+ERTS_GLB_INLINE ErtsMonotonicTime erts_os_monotonic_time(void);
+
+#if ERTS_GLB_INLINE_INCL_FUNC_DEF
+
+ERTS_GLB_INLINE ErtsMonotonicTime
+erts_os_monotonic_time(void)
+{
+    return (*erts_sys_time_data__.r.o.os_monotonic_time)();
+}
+
+#endif /* ERTS_GLB_INLINE_INCL_FUNC_DEF */
+
+#endif /* ERTS_OS_MONOTONIC_INLINE_FUNC_PTR_CALL__ */
+
+/*
+ *
+ */
 
 #if (defined(HAVE_GETHRVTIME) || defined(HAVE_CLOCK_GETTIME))
 typedef long long SysCpuTime;
diff --git a/erts/emulator/sys/unix/sys.c b/erts/emulator/sys/unix/sys.c
index 0d677d5f34..70f549a37a 100644
--- a/erts/emulator/sys/unix/sys.c
+++ b/erts/emulator/sys/unix/sys.c
@@ -280,7 +280,7 @@ struct {
     int (*event)(ErlDrvPort, ErlDrvEvent, ErlDrvEventData);
     void (*check_io_as_interrupt)(void);
     void (*check_io_interrupt)(int);
-    void (*check_io_interrupt_tmd)(int, erts_short_time_t);
+    void (*check_io_interrupt_tmd)(int, ErtsMonotonicTime);
     void (*check_io)(int);
     Uint (*size)(void);
     Eterm (*info)(void *);
@@ -386,9 +386,9 @@ erts_sys_schedule_interrupt(int set)
 
 #ifdef ERTS_SMP
 void
-erts_sys_schedule_interrupt_timed(int set, erts_short_time_t msec)
+erts_sys_schedule_interrupt_timed(int set, ErtsMonotonicTime timeout_time)
 {
-    ERTS_CHK_IO_INTR_TMD(set, msec);
+    ERTS_CHK_IO_INTR_TMD(set, timeout_time);
 }
 #endif
 
@@ -984,24 +984,6 @@ static void unblock_signals(void)
 #endif /* #ifndef ETHR_UNUSABLE_SIGUSRX */
 #endif
 }
-/************************** Time stuff **************************/
-#ifdef HAVE_GETHRTIME
-#ifdef GETHRTIME_WITH_CLOCK_GETTIME
-
-SysHrTime sys_gethrtime(void)
-{
-    struct timespec ts;
-    long long result;
-    if (clock_gettime(CLOCK_MONOTONIC,&ts) != 0) {
-	erl_exit(1,"Fatal, could not get clock_monotonic value!, "
-		 "errno = %d\n", errno);
-    }
-    result = ((long long) ts.tv_sec) * 1000000000LL + 
-	((long long) ts.tv_nsec);
-    return (SysHrTime) result;
-}
-#endif
-#endif
 
 /************************** OS info *******************************/
 
diff --git a/erts/emulator/sys/unix/sys_time.c b/erts/emulator/sys/unix/sys_time.c
index fcce54a2c4..9fdb1930b7 100644
--- a/erts/emulator/sys/unix/sys_time.c
+++ b/erts/emulator/sys/unix/sys_time.c
@@ -53,9 +53,40 @@
 
 /******************* Routines for time measurement *********************/
 
-int erts_ticks_per_sec = 0; /* Will be SYS_CLK_TCK in erl_unix_sys.h */
-int erts_ticks_per_sec_wrap = 0; /* Will be SYS_CLK_TCK_WRAP */
-static int ticks_bsr = 0; /* Shift wrapped tick value this much to the right */
+#undef ERTS_SYS_TIME_INTERNAL_STATE_WRITE_FREQ__
+#undef ERTS_SYS_TIME_INTERNAL_STATE_READ_ONLY__
+
+#if defined(OS_MONOTONIC_TIME_USING_TIMES)
+
+#define ERTS_WRAP_SYS_TIMES 1
+#define ERTS_SYS_TIME_INTERNAL_STATE_WRITE_FREQ__
+#define ERTS_SYS_TIME_INTERNAL_STATE_READ_ONLY__
+
+/*
+ * Not sure there is a need to use times() anymore, perhaps drop
+ * support for this soon...
+ *
+ * sys_times() might need to be wrapped and the values shifted (right)
+ * a bit to cope with faster ticks, this has to be taken care 
+ * of dynamically to start with, a special version that uses
+ * the times() return value as a high resolution timer can be made
+ * to fully utilize the faster ticks, like on windows, but for now, we'll
+ * settle with this silly workaround
+ */
+#ifdef ERTS_WRAP_SYS_TIMES
+static clock_t sys_times_wrap(void);
+#define KERNEL_TICKS() (sys_times_wrap() &  \
+			((1UL << ((sizeof(clock_t) * 8) - 1)) - 1)) 
+#define ERTS_KERNEL_TICK_TO_USEC(TCKS) (((TCKS)*(1000*1000)) \
+					/ internal_state.r.o.ticks_per_sec_wrap)
+#else
+
+#define KERNEL_TICKS() (sys_times(&internal_state.w.f.dummy_tms) &  \
+			((1UL << ((sizeof(clock_t) * 8) - 1)) - 1)) 
+#define ERTS_KERNEL_TICK_TO_USEC(TCKS) (((TCKS)*(1000*1000))/SYS_CLK_TCK)
+#endif
+
+#endif
 
 /* 
  * init timers, chose a tick length, and return it.
@@ -63,37 +94,374 @@ static int ticks_bsr = 0; /* Shift wrapped tick value this much to the right */
  * does almost everything. Other platforms have to
  * emulate Unix in this sense.
  */
-int sys_init_time(void)
+
+ErtsSysTimeData__ erts_sys_time_data__ erts_align_attribute(ERTS_CACHE_LINE_SIZE);
+
+#if defined(__linux__) && defined(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME)
+
+#define ERTS_SYS_TIME_INTERNAL_STATE_WRITE_FREQ__
+
+ErtsMonotonicTime clock_gettime_monotonic_raw(void);
+ErtsMonotonicTime clock_gettime_monotonic_verified(void);
+
+#endif /* defined(__linux__) && defined(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME) */
+
+#ifdef ERTS_SYS_TIME_INTERNAL_STATE_READ_ONLY__
+struct sys_time_internal_state_read_only__ {
+#if defined(OS_MONOTONIC_TIME_USING_TIMES)
+    int ticks_bsr;
+    int ticks_per_sec_wrap;
+#endif
+};
+#endif
+
+#ifdef ERTS_SYS_TIME_INTERNAL_STATE_WRITE_FREQ__
+struct sys_time_internal_state_write_freq__ {
+    erts_smp_mtx_t mtx;
+#if defined(__linux__) && defined(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME)
+    ErtsMonotonicTime last_delivered;
+#endif
+#if defined(OS_MONOTONIC_TIME_USING_TIMES)
+    ErtsMonotonicTime last_tick_count;
+    ErtsMonotonicTime last_tick_wrap_count;
+    ErtsMonotonicTime last_tick_monotonic_time;
+    ErtsMonotonicTime last_timeofday_usec;
+#ifndef ERTS_WRAP_SYS_TIMES 
+    SysTimes dummy_tms;
+#endif
+#endif
+};
+#endif
+
+#if defined(ERTS_SYS_TIME_INTERNAL_STATE_READ_ONLY__)	\
+    || defined(ERTS_SYS_TIME_INTERNAL_STATE_WRITE_FREQ__)
+static struct {
+#ifdef ERTS_SYS_TIME_INTERNAL_STATE_READ_ONLY__
+    union {
+	struct sys_time_internal_state_read_only__ o;
+	char align__[(((sizeof(struct sys_time_internal_state_read_only__) - 1)
+		       / ASSUMED_CACHE_LINE_SIZE) + 1)
+		     * ASSUMED_CACHE_LINE_SIZE];
+    } r;
+#endif
+#ifdef ERTS_SYS_TIME_INTERNAL_STATE_WRITE_FREQ__
+    union {
+	struct sys_time_internal_state_write_freq__ f;
+	char align__[(((sizeof(struct sys_time_internal_state_write_freq__) - 1)
+		       / ASSUMED_CACHE_LINE_SIZE) + 1)
+		     * ASSUMED_CACHE_LINE_SIZE];
+    } w;
+#endif
+} internal_state erts_align_attribute(ERTS_CACHE_LINE_SIZE);
+#endif
+
+void
+sys_init_time(ErtsSysInitTimeResult *init_resp)
 {
+#if !defined(ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT)
+
+    init_resp->have_os_monotonic = 0;
+
+#else /* defined(ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT) */
+
+    int major, minor, build, vsn;
+
+    init_resp->os_monotonic_info.resolution = (Uint64) 1000*1000*1000;
+#if defined(HAVE_CLOCK_GETRES) && defined(MONOTONIC_CLOCK_ID)
+    {
+	struct timespec ts;
+	if (clock_getres(MONOTONIC_CLOCK_ID, &ts) == 0
+	    && ts.tv_sec == 0 && ts.tv_nsec != 0) {
+	    init_resp->os_monotonic_info.resolution /= ts.tv_nsec;
+	}
+    }
+#endif
+
+#ifdef MONOTONIC_CLOCK_ID_STR
+    init_resp->os_monotonic_info.clock_id = MONOTONIC_CLOCK_ID_STR;
+#else
+    init_resp->os_monotonic_info.clock_id = NULL;
+#endif
+
+    init_resp->os_monotonic_info.locked_use = 0;
+
+#if defined(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME)
+    init_resp->os_monotonic_info.func = "clock_gettime";
+#elif defined(OS_MONOTONIC_TIME_USING_MACH_CLOCK_GET_TIME)
+    init_resp->os_monotonic_info.func = "clock_get_time";
+#elif defined(OS_MONOTONIC_TIME_USING_GETHRTIME)
+    init_resp->os_monotonic_info.func = "gethrtime";
+#elif defined(OS_MONOTONIC_TIME_USING_TIMES)
+    init_resp->os_monotonic_info.func = "times";
+    init_resp->os_monotonic_info.locked_use = 1;
+    init_resp->os_monotonic_info.resolution = TICKS_PER_SEC();
+#else
+# error Unknown erts_os_monotonic_time() implementation
+#endif
+
+    init_resp->have_os_monotonic = 1;
+
+    os_version(&major, &minor, &build);
+
+    vsn = ERTS_MK_VSN_INT(major, minor, build);
+
+
+#if defined(__linux__) && defined(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME)
+    if (vsn >= ERTS_MK_VSN_INT(2, 6, 33))
+	erts_sys_time_data__.r.o.os_monotonic_time =
+	    clock_gettime_monotonic_raw;
+    else {
+	/*
+	 * Linux versions prior to 2.6.33 have a
+	 * known bug that sometimes cause monotonic
+	 * time to take small steps backwards.
+	 */
+	erts_sys_time_data__.r.o.os_monotonic_time =
+	    clock_gettime_monotonic_verified;
+	erts_smp_mtx_init(&internal_state.w.f.mtx,
+			  "os_monotonic_time");
+	internal_state.w.f.last_delivered
+	    = clock_gettime_monotonic_raw();
+	init_resp->os_monotonic_info.locked_use = 1;
+    }
+#else /* !(defined(__linux__) && defined(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME)) */
+    {
+	char flavor[1024];
+
+	os_flavor(flavor, sizeof(flavor));
+
+	if (sys_strcmp(flavor, "sunos") == 0) {
+	    /*
+	     * Don't trust hrtime on multi processors
+	     * on SunOS prior to SunOS 5.8
+	     */
+	    if (vsn < ERTS_MK_VSN_INT(5, 8, 0)) {
+#if defined(HAVE_SYSCONF) && defined(_SC_NPROCESSORS_CONF)
+		if (sysconf(_SC_NPROCESSORS_CONF) > 1)
+#endif
+		    init_resp->have_os_monotonic = 0;
+	    }
+	}
+    }
+#endif /* !(defined(__linux__) && defined(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME)) */
+
+#endif /* defined(ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT) */
+
+    init_resp->os_monotonic_time_unit = ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT;
+    init_resp->sys_clock_resolution = SYS_CLOCK_RESOLUTION;
+
     /* 
-     * This (erts_ticks_per_sec) is only for times() (CLK_TCK), 
-     * the resolution is always one millisecond..
+     * This (erts_sys_time_data__.r.o.ticks_per_sec) is only for
+     * times() (CLK_TCK), the resolution is always one millisecond..
      */
-    if ((erts_ticks_per_sec = TICKS_PER_SEC()) < 0)
-	erl_exit(1, "Can't get clock ticks/sec\n");
-    if (erts_ticks_per_sec >= 1000) {
+    if ((erts_sys_time_data__.r.o.ticks_per_sec = TICKS_PER_SEC()) < 0)
+	erl_exit(ERTS_ABORT_EXIT, "Can't get clock ticks/sec\n");
+    
+#if defined(OS_MONOTONIC_TIME_USING_TIMES)
+
+    if (erts_sys_time_data__.r.o.ticks_per_sec >= 1000) {
 	/* Workaround for beta linux kernels, need to be done in runtime
 	   to make erlang run on both 2.4 and 2.5 kernels. In the future, 
 	   the kernel ticks might as 
 	   well be used as a high res timer instead, but that's for when the 
 	   majority uses kernels with HZ == 1024 */
-	ticks_bsr = 3;
+	internal_state.r.o.ticks_bsr = 3;
     } else {
-	ticks_bsr = 0;
+	internal_state.r.o.ticks_bsr = 0;
     }
-    erts_ticks_per_sec_wrap = (erts_ticks_per_sec >> ticks_bsr);
-    return SYS_CLOCK_RESOLUTION;
+
+    internal_state.r.o.ticks_per_sec_wrap
+	= (erts_sys_time_data__.r.o.ticks_per_sec
+	   >> internal_state.r.o.ticks_bsr);
+
+    erts_smp_mtx_init(&internal_state.w.f.mtx, "os_monotonic_time");
+    internal_state.w.f.last_tick_count = KERNEL_TICKS();
+    internal_state.w.f.last_tick_wrap_count = 0;    
+    internal_state.w.f.last_tick_monotonic_time
+	= ERTS_KERNEL_TICK_TO_USEC(internal_state.w.f.last_tick_count);
+    {
+	SysTimeval tv;
+	sys_gettimeofday(&tv);
+	internal_state.w.f.last_timeofday_usec = tv.tv_sec*(1000*1000);
+	internal_state.w.f.last_timeofday_usec += tv.tv_usec;
+    }
+
+#endif /* defined(OS_MONOTONIC_TIME_USING_TIMES) */
+
+}
+
+#if defined(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME)
+
+static ERTS_INLINE ErtsMonotonicTime
+clock_gettime_monotonic(void)
+{
+    ErtsMonotonicTime mtime;
+    struct timespec ts;
+
+    if (clock_gettime(MONOTONIC_CLOCK_ID,&ts) != 0) {
+	int err = errno;
+	char *errstr = err ? strerror(err) : "unknown";
+	erl_exit(ERTS_ABORT_EXIT,
+		 "clock_gettime(%s, _) failed: %s (%d)\n",
+		 MONOTONIC_CLOCK_ID_STR, errstr, err);
+
+    }
+    mtime = (ErtsMonotonicTime) ts.tv_sec;
+    mtime *= (ErtsMonotonicTime) 1000*1000*1000;
+    mtime += (ErtsMonotonicTime) ts.tv_nsec;
+    return mtime;
+}
+
+#if defined(__linux__)
+
+ErtsMonotonicTime clock_gettime_monotonic_verified(void)
+{
+    ErtsMonotonicTime mtime;
+
+    mtime = clock_gettime_monotonic();
+
+    erts_smp_mtx_lock(&internal_state.w.f.mtx);
+    if (mtime < internal_state.w.f.last_delivered)
+	mtime = internal_state.w.f.last_delivered;
+    else
+	internal_state.w.f.last_delivered = mtime;
+    erts_smp_mtx_unlock(&internal_state.w.f.mtx);
+
+    return mtime;
+}
+
+ErtsMonotonicTime clock_gettime_monotonic_raw(void)
+{
+    return clock_gettime_monotonic();
 }
 
-clock_t sys_times_wrap(void)
+#else /* !defined(__linux__) */
+
+ErtsMonotonicTime erts_os_monotonic_time(void)
+{
+    return clock_gettime_monotonic();
+}
+
+#endif /* !defined(__linux__) */
+
+#elif defined(OS_MONOTONIC_TIME_USING_MACH_CLOCK_GET_TIME)
+
+#include <mach/clock.h>
+#include <mach/mach.h>
+
+ErtsMonotonicTime erts_os_monotonic_time(void)
+{
+    ErtsMonotonicTime mtime;
+    kern_return_t res;
+    clock_serv_t clk_srv;
+    mach_timespec_t time_spec;
+    int err;
+
+    host_get_clock_service(mach_host_self(),
+			   MONOTONIC_CLOCK_ID,
+			   &clk_srv);
+    errno = 0;
+    res = clock_get_time(clk_srv, &time_spec);
+    err = errno;
+    mach_port_deallocate(mach_task_self(), clk_srv);
+    if (res != KERN_SUCCESS) {
+	char *errstr = err ? strerror(err) : "unknown";
+	erl_exit(ERTS_ABORT_EXIT,
+		 "clock_get_time(%s, _) failed: %s (%d)\n",
+		 MONOTONIC_CLOCK_ID_STR, errstr, err);
+    }
+
+    mtime = (ErtsMonotonicTime) time_spec.tv_sec;
+    mtime *= (ErtsMonotonicTime) 1000*1000*1000;
+    mtime += (ErtsMonotonicTime) time_spec.tv_nsec;
+    return mtime;
+}
+
+#elif defined(OS_MONOTONIC_TIME_USING_TIMES)
+
+static clock_t sys_times_wrap(void)
 {
     SysTimes dummy;
-    clock_t result = (sys_times(&dummy) >> ticks_bsr);
+    clock_t result = (sys_times(&dummy) >> internal_state.r.o.ticks_bsr);
     return result;
 }
 
+void
+erts_os_time_offset_finalize(void)
+{
+    erts_smp_mtx_lock(&internal_state.w.f.mtx);
+    internal_state.w.f.last_tick_wrap_count = 0;
+    erts_smp_mtx_unlock(&internal_state.w.f.mtx);
+}
+
+#define ERTS_TIME_EXCEED_TICK_LIMIT(SYS_TIME, TCK_TIME)			\
+    (((Uint64) (SYS_TIME)) - (((Uint64) (TCK_TIME))			\
+			      - ERTS_KERNEL_TICK_TO_USEC(1))		\
+     > ERTS_KERNEL_TICK_TO_USEC(2))
+
+/* Returns monotonic time in micro seconds */
+ErtsMonotonicTime
+erts_os_monotonic_time(void)
+{
+    SysTimeval tv;
+    ErtsMonotonicTime res;
+    ErtsMonotonicTime tick_count;
+    ErtsMonotonicTime tick_count_usec;
+    ErtsMonotonicTime tick_monotonic_time;
+    ErtsMonotonicTime timeofday_usec;
+    ErtsMonotonicTime timeofday_diff_usec;
+
+    erts_smp_mtx_lock(&internal_state.w.f.mtx);
 
+    tick_count = (ErtsMonotonicTime) KERNEL_TICKS();
+    sys_gettimeofday(&tv);
+
+    if (internal_state.w.f.last_tick_count > tick_count) {
+	internal_state.w.f.last_tick_wrap_count
+	    += (((ErtsMonotonicTime) 1) << ((sizeof(clock_t) * 8) - 1));
+    }
+    internal_state.w.f.last_tick_count = tick_count;
+    tick_count += internal_state.w.f.last_tick_wrap_count;
+
+    tick_count_usec = ERTS_KERNEL_TICK_TO_USEC(tick_count);
+
+    timeofday_usec = (ErtsMonotonicTime) tv.tv_sec*(1000*1000);
+    timeofday_usec += (ErtsMonotonicTime) tv.tv_usec;
+    timeofday_diff_usec = timeofday_usec;
+    timeofday_diff_usec -= internal_state.w.f.last_timeofday_usec;
+    internal_state.w.f.last_timeofday_usec = timeofday_usec;
+
+    if (timeofday_diff_usec < 0) {
+	/* timeofday jumped backwards use tick count only... */
+	tick_monotonic_time = tick_count_usec;
+    }
+    else {
+	/* Use time diff from of timeofday if not off by too much... */
+	tick_monotonic_time = internal_state.w.f.last_tick_monotonic_time;
+	tick_monotonic_time += timeofday_diff_usec;
+
+	if (ERTS_TIME_EXCEED_TICK_LIMIT(tick_monotonic_time, tick_count_usec)) {
+	    /*
+	     * Value off by more than one tick from tick_count, i.e.
+	     * timofday leaped one way or the other. We use
+	     * tick_count_usec as is instead and unfortunately
+	     * get lousy precision.
+	     */
+	    tick_monotonic_time = tick_count_usec;
+	}
+    }
+
+    if (internal_state.w.f.last_tick_monotonic_time < tick_monotonic_time)
+	internal_state.w.f.last_tick_monotonic_time = tick_monotonic_time;
+
+    res = internal_state.w.f.last_tick_monotonic_time;
+
+    erts_smp_mtx_unlock(&internal_state.w.f.mtx);
+
+    return res;
+}
 
+#endif  /* !defined(OS_MONOTONIC_TIME_USING_TIMES) */
 
 #ifdef HAVE_GETHRVTIME_PROCFS_IOCTL
 
diff --git a/erts/emulator/sys/win32/erl_poll.c b/erts/emulator/sys/win32/erl_poll.c
index 972170d465..5a62b00a68 100644
--- a/erts/emulator/sys/win32/erl_poll.c
+++ b/erts/emulator/sys/win32/erl_poll.c
@@ -285,7 +285,7 @@ struct ErtsPollSet_ {
 #ifdef ERTS_SMP
     erts_smp_mtx_t mtx;
 #endif
-    erts_smp_atomic32_t timeout;
+    erts_atomic64_t timeout_time;
 };
 
 #ifdef ERTS_SMP
@@ -363,6 +363,26 @@ do { \
     wait_standby(PS); \
  } while(0)
 
+static ERTS_INLINE void
+init_timeout_time(ErtsPollSet ps)
+{
+    erts_atomic64_init_nob(&ps->timeout_time,
+			   (erts_aint64_t) ERTS_MONOTONIC_TIME_MAX);
+}
+
+static ERTS_INLINE void
+set_timeout_time(ErtsPollSet ps, ErtsMonotonicTime time)
+{
+    erts_atomic64_set_relb(&ps->timeout_time,
+			   (erts_aint64_t) time);
+}
+
+static ERTS_INLINE ErtsMonotonicTime
+get_timeout_time(ErtsPollSet ps)
+{
+    return (ErtsMonotonicTime) erts_atomic64_read_acqb(&ps->timeout_time);
+}
+
 #define ERTS_POLL_NOT_WOKEN		((erts_aint32_t) 0)
 #define ERTS_POLL_WOKEN_IO_READY	((erts_aint32_t) 1)
 #define ERTS_POLL_WOKEN_INTR		((erts_aint32_t) 2)
@@ -422,15 +442,29 @@ wakeup_cause(ErtsPollSet ps)
 }
 
 static ERTS_INLINE DWORD
-poll_wait_timeout(ErtsPollSet ps, SysTimeval *tvp)
+poll_wait_timeout(ErtsPollSet ps, ErtsMonotonicTime timeout_time)
 {
-    time_t timeout = tvp->tv_sec * 1000 + tvp->tv_usec / 1000;
+    ErtsMonotonicTime current_time, diff_time, timeout;
 
-    if (timeout <= 0) {
+    if (timeout_time == ERTS_POLL_NO_TIMEOUT) {
+    no_timeout:
+	set_timeout_time(ps, ERTS_MONOTONIC_TIME_MIN);
 	woke_up(ps);
 	return (DWORD) 0;
     }
 
+    current_time = erts_get_monotonic_time();
+    diff_time = timeout_time - current_time;
+    if (diff_time <= 0)
+	goto no_timeout;
+
+    /* Round up to nearest milli second */
+    timeout = (ERTS_MONOTONIC_TO_MSEC(diff_time - 1) + 1);
+    if (timeout > INT_MAX)
+	timeout = INT_MAX; /* Also prevents DWORD overflow */
+
+    set_timeout_time(ps, current_time + ERTS_MSEC_TO_MONOTONIC(timeout));
+
     ResetEvent(ps->event_io_ready);
     /*
      * Since we don't know the internals of ResetEvent() we issue
@@ -442,10 +476,6 @@ poll_wait_timeout(ErtsPollSet ps, SysTimeval *tvp)
     if (erts_atomic32_read_nob(&ps->wakeup_state) != ERTS_POLL_NOT_WOKEN)
 	return (DWORD) 0;
 
-    if (timeout > ((time_t) ERTS_AINT32_T_MAX))
-	timeout = ERTS_AINT32_T_MAX; /* Also prevents DWORD overflow */
-
-    erts_smp_atomic32_set_relb(&ps->timeout, (erts_aint32_t) timeout);
     return (DWORD) timeout;
 }
 
@@ -1012,12 +1042,12 @@ void  erts_poll_interrupt(ErtsPollSet ps, int set /* bool */)
 
 void erts_poll_interrupt_timed(ErtsPollSet ps,
 			       int set /* bool */,
-			       erts_short_time_t msec)
+			       ErtsMonotonicTime timeout_time)
 {
-    HARDTRACEF(("In erts_poll_interrupt_timed(%d,%ld)",set,msec));
+    HARDTRACEF(("In erts_poll_interrupt_timed(%d,%ld)",set,timeout_time));
     if (!set)
 	reset_interrupt(ps);
-    else if (erts_smp_atomic32_read_acqb(&ps->timeout) > (erts_aint32_t) msec)
+    else if (get_timeout_time(ps) > timeout_time)
 	set_interrupt(ps);
     HARDTRACEF(("Out erts_poll_interrupt_timed"));
 }
@@ -1092,7 +1122,7 @@ void erts_poll_controlv(ErtsPollSet ps,
 int erts_poll_wait(ErtsPollSet ps,
 		   ErtsPollResFd pr[],
 		   int *len,
-		   SysTimeval *tvp)
+		   ErtsMonotonicTime timeout_time)
 {
     int no_fds;
     DWORD timeout;
@@ -1149,7 +1179,7 @@ int erts_poll_wait(ErtsPollSet ps,
 	no_fds = ERTS_POLL_MAX_RES;
 #endif
 
-    timeout = poll_wait_timeout(ps, tvp);
+    timeout = poll_wait_timeout(ps, timeout_time);
 
     /*HARDDEBUGF(("timeout = %ld",(long) timeout));*/
 
@@ -1242,7 +1272,7 @@ int erts_poll_wait(ErtsPollSet ps,
 	erts_mtx_unlock(&w->mtx);
     }
  done:
-    erts_smp_atomic32_set_nob(&ps->timeout, ERTS_AINT32_T_MAX);
+    set_timeout_time(ps, ERTS_MONOTONIC_TIME_MAX);
     *len = num;
     ERTS_POLLSET_UNLOCK(ps);
     HARDTRACEF(("Out erts_poll_wait"));
@@ -1326,7 +1356,7 @@ ErtsPollSet erts_poll_create_pollset(void)
 #ifdef ERTS_SMP
     erts_smp_mtx_init(&ps->mtx, "pollset");
 #endif
-    erts_smp_atomic32_init_nob(&ps->timeout, ERTS_AINT32_T_MAX);
+    init_timeout_time(ps);
 
     HARDTRACEF(("Out erts_poll_create_pollset"));
     return ps;
diff --git a/erts/emulator/sys/win32/erl_win_sys.h b/erts/emulator/sys/win32/erl_win_sys.h
index 838f0c61eb..f04bb6a0e5 100644
--- a/erts/emulator/sys/win32/erl_win_sys.h
+++ b/erts/emulator/sys/win32/erl_win_sys.h
@@ -120,9 +120,6 @@
 /*
  * For erl_time_sup
  */
-#define HAVE_GETHRTIME
-
-#define sys_init_hrtime() /* Nothing */
 
 #define SYS_CLK_TCK 1000
 #define SYS_CLOCK_RESOLUTION 1
@@ -164,18 +161,58 @@ typedef struct {
 #if defined (__GNUC__)
 typedef unsigned long long Uint64;
 typedef long long          Sint64;
-
-typedef long long SysHrTime;
+#  ifdef ULLONG_MAX
+#    define ERTS_UINT64_MAX ULLONG_MAX
+#  endif
+#  ifdef LLONG_MAX
+#    define ERTS_SINT64_MAX LLONG_MAX
+#  endif
+#  ifdef LLONG_MIN
+#    define ERTS_SINT64_MIN LLONG_MIN
+#  endif
+
+typedef long long ErtsMonotonicTime;
 #else
 typedef ULONGLONG Uint64;
 typedef LONGLONG  Sint64;
 
-typedef LONGLONG SysHrTime;
+typedef LONGLONG ErtsMonotonicTime;
 #endif
 
-extern int sys_init_time(void);
+#define ERTS_MONOTONIC_TIME_MIN (((ErtsMonotonicTime) 1) << 63)
+#define ERTS_MONOTONIC_TIME_MAX (~ERTS_MONOTONIC_TIME_MIN)
+
+#define ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT 1
+#define ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT 0
+
+struct erts_sys_time_read_only_data__ {
+    ErtsMonotonicTime (*os_monotonic_time)(void);
+};
+
+typedef struct {
+    union {
+	struct erts_sys_time_read_only_data__ o;
+	char align__[(((sizeof(struct erts_sys_time_read_only_data__) - 1)
+		       / ASSUMED_CACHE_LINE_SIZE) + 1)
+		     * ASSUMED_CACHE_LINE_SIZE];
+    } r;
+} ErtsSysTimeData__;
+
+extern ErtsSysTimeData__ erts_sys_time_data__;
+
+ERTS_GLB_INLINE ErtsMonotonicTime erts_os_monotonic_time(void);
+
+#if ERTS_GLB_INLINE_INCL_FUNC_DEF
+
+ERTS_GLB_INLINE ErtsMonotonicTime
+erts_os_monotonic_time(void)
+{
+    return (*erts_sys_time_data__.r.o.os_monotonic_time)();
+}
+
+#endif /* ERTS_GLB_INLINE_INCL_FUNC_DEF */
+
 extern void sys_gettimeofday(SysTimeval *tv);
-extern SysHrTime sys_gethrtime(void);
 extern clock_t sys_times(SysTimes *buffer);
 
 extern char *win_build_environment(char *);
diff --git a/erts/emulator/sys/win32/sys.c b/erts/emulator/sys/win32/sys.c
index 0ded6b274e..8eed1c6d9b 100644
--- a/erts/emulator/sys/win32/sys.c
+++ b/erts/emulator/sys/win32/sys.c
@@ -3258,9 +3258,9 @@ erts_sys_schedule_interrupt(int set)
 
 #ifdef ERTS_SMP
 void
-erts_sys_schedule_interrupt_timed(int set, erts_short_time_t msec)
+erts_sys_schedule_interrupt_timed(int set, ErtsMonotonicTime timeout_time)
 {
-    erts_check_io_interrupt_timed(set, msec);
+    erts_check_io_interrupt_timed(set, timeout_time);
 }
 #endif
 
diff --git a/erts/emulator/sys/win32/sys_time.c b/erts/emulator/sys/win32/sys_time.c
index b84c8f85ce..3a10125c81 100644
--- a/erts/emulator/sys/win32/sys_time.c
+++ b/erts/emulator/sys/win32/sys_time.c
@@ -61,11 +61,6 @@
 	(epoch) = ((ull.QuadPart / TICKS_PER_SECOND) - EPOCH_JULIAN_DIFF); \
     } while(0)
  
-static SysHrTime wrap = 0;
-static DWORD last_tick_count = 0;
-static erts_smp_mtx_t wrap_lock;
-static ULONGLONG (WINAPI *pGetTickCount64)(void) = NULL;
-
 /* Getting timezone information is a heavy operation, so we want to do this 
    only once */
 
@@ -76,17 +71,161 @@ static int days_in_month[2][13] = {
     {0,31,28,31,30,31,30,31,31,30,31,30,31},
     {0,31,29,31,30,31,30,31,31,30,31,30,31}};
 
-int 
-sys_init_time(void)
+/*
+ * erts_os_monotonic_time()
+ */
+
+struct sys_time_internal_state_read_only__ {
+    ULONGLONG (WINAPI *pGetTickCount64)(void);
+    BOOL (WINAPI *pQueryPerformanceCounter)(LARGE_INTEGER *);
+};
+
+struct sys_time_internal_state_write_freq__ {
+    erts_smp_mtx_t mtime_mtx;
+    ULONGLONG wrap;
+    ULONGLONG last_tick_count;
+};
+
+__declspec(align(ASSUMED_CACHE_LINE_SIZE)) struct {
+    union {
+	struct sys_time_internal_state_read_only__ o;
+	char align__[(((sizeof(struct sys_time_internal_state_read_only__) - 1)
+		       / ASSUMED_CACHE_LINE_SIZE) + 1)
+		     * ASSUMED_CACHE_LINE_SIZE];
+    } r;
+    union {
+	struct sys_time_internal_state_write_freq__ f;
+	char align__[(((sizeof(struct sys_time_internal_state_write_freq__) - 1)
+		       / ASSUMED_CACHE_LINE_SIZE) + 1)
+		     * ASSUMED_CACHE_LINE_SIZE];
+    } w;
+} internal_state;
+
+__declspec(align(ASSUMED_CACHE_LINE_SIZE)) ErtsSysTimeData__ erts_sys_time_data__;
+
+static ErtsMonotonicTime
+os_monotonic_time_qpc(void)
 {
+    LARGE_INTEGER pc;
+
+    if (!(*internal_state.r.o.pQueryPerformanceCounter)(&pc))
+	erl_exit(ERTS_ABORT_EXIT, "QueryPerformanceCounter() failed\n");
+
+    return (ErtsMonotonicTime) pc.QuadPart;
+}
+
+static ErtsMonotonicTime
+os_monotonic_time_gtc32(void) 
+{
+    ULONGLONG res, ticks;
+
+    erts_smp_mtx_lock(&internal_state.w.f.mtime_mtx);
+
+    ticks = (ULONGLONG) (GetTickCount() & 0x7FFFFFFF);
+    if (ticks < internal_state.w.f.last_tick_count)
+	internal_state.w.f.wrap += (ULONGLONG) LL_LITERAL(1) << 31;
+    internal_state.w.f.last_tick_count = ticks;
+    res = ticks + internal_state.w.f.wrap;
+
+    erts_smp_mtx_unlock(&internal_state.w.f.mtime_mtx);
+
+    return (ErtsMonotonicTime) res*1000;
+}
+
+static ErtsMonotonicTime
+os_monotonic_time_gtc64(void) 
+{
+    ULONGLONG ticks = (*internal_state.r.o.pGetTickCount64)();
+    return (ErtsMonotonicTime) ticks*1000;
+}
+
+/*
+ * Init
+ */
+
+void
+sys_init_time(ErtsSysInitTimeResult *init_resp)
+{
+    ErtsMonotonicTime (*os_mtime_func)(void);
+    ErtsMonotonicTime time_unit;
     char kernel_dll_name[] = "kernel32";
     HMODULE module;
 
+    init_resp->os_monotonic_info.clock_id = NULL;
+
     module = GetModuleHandle(kernel_dll_name);
-    pGetTickCount64 = (module != NULL) ? 
-	(ULONGLONG (WINAPI *)(void)) 
-	GetProcAddress(module,"GetTickCount64") : 
-	NULL;
+    if (!module) {
+    get_tick_count:
+	erts_smp_mtx_init(&internal_state.w.f.mtime_mtx,
+			  "os_monotonic_time");
+	internal_state.w.f.wrap = 0;
+	internal_state.w.f.last_tick_count = 0;
+
+	init_resp->os_monotonic_info.func = "GetTickCount";
+	init_resp->os_monotonic_info.locked_use = 1;
+	init_resp->os_monotonic_info.resolution = 1000;
+	time_unit = (ErtsMonotonicTime) 1000*1000;
+	os_mtime_func = os_monotonic_time_gtc32;
+    }
+    else {
+	int major, minor, build;
+
+	os_version(&major, &minor, &build);
+
+	if (major < 6) {
+
+	get_tick_count64:
+
+	    internal_state.r.o.pGetTickCount64
+		= ((ULONGLONG (WINAPI *)(void))
+		   GetProcAddress(module, "GetTickCount64"));
+	    if (!internal_state.r.o.pGetTickCount64)
+		goto get_tick_count;
+
+	    init_resp->os_monotonic_info.func = "GetTickCount64";
+	    init_resp->os_monotonic_info.locked_use = 0;
+	    init_resp->os_monotonic_info.resolution = 1000;
+	    time_unit = (ErtsMonotonicTime) 1000*1000;
+	    os_mtime_func = os_monotonic_time_gtc64;
+	}
+	else { /* Vista or newer... */
+
+	    LARGE_INTEGER pf;
+	    BOOL (WINAPI *QPF)(LARGE_INTEGER *);
+
+	    QPF = ((BOOL (WINAPI *)(LARGE_INTEGER *))
+		   GetProcAddress(module, "QueryPerformanceFrequency"));
+	    if (!QPF)
+		goto get_tick_count64;
+	    if (!(*QPF)(&pf))
+		goto get_tick_count64;
+	    /*
+	     * We only use QueryPerformanceCounter() if
+	     * its frequency is equal to, or larger than
+	     * GHz in order to ensure that the user wont
+	     * be able to observe faulty order between
+	     * values retrieved on different threads.
+	     */
+	    if (pf.QuadPart < (LONGLONG) 1000*1000*1000)
+		goto get_tick_count64;
+	    internal_state.r.o.pQueryPerformanceCounter
+		= ((BOOL (WINAPI *)(LARGE_INTEGER *))
+		   GetProcAddress(module, "QueryPerformanceCounter"));
+	    if (!internal_state.r.o.pQueryPerformanceCounter)
+		goto get_tick_count64;
+
+	    init_resp->os_monotonic_info.func = "QueryPerformanceCounter";
+	    init_resp->os_monotonic_info.locked_use = 0;
+	    time_unit = (ErtsMonotonicTime) pf.QuadPart;
+	    init_resp->os_monotonic_info.resolution = time_unit;
+	    os_mtime_func = os_monotonic_time_qpc;
+	}
+    }
+
+    erts_sys_time_data__.r.o.os_monotonic_time = os_mtime_func;
+    init_resp->os_monotonic_time_unit = time_unit;
+    init_resp->have_os_monotonic = 1;
+    init_resp->sys_clock_resolution = 1;
 
     if(GetTimeZoneInformation(&static_tzi) && 
        static_tzi.StandardDate.wMonth != 0 &&
@@ -94,9 +233,6 @@ sys_init_time(void)
 	have_static_tzi = 1;
     }
 
-    erts_smp_mtx_init(&wrap_lock, "sys_gethrtime");
-
-    return 1;
 }
 
 /* Returns a switchtimes for DST as UTC filetimes given data from a 
@@ -377,41 +513,6 @@ sys_gettimeofday(SysTimeval *tv)
 			 EPOCH_JULIAN_DIFF);
 }
 
-extern int erts_initialized;
-SysHrTime 
-sys_gethrtime(void) 
-{
-    if (pGetTickCount64 != NULL) {
-	return ((SysHrTime) pGetTickCount64()) * LL_LITERAL(1000000);
-    } else {
-	DWORD ticks;
-	SysHrTime res;
-	erts_smp_mtx_lock(&wrap_lock);
-	ticks = (SysHrTime) (GetTickCount() & 0x7FFFFFFF);
-	if (ticks < (SysHrTime) last_tick_count) {
-	    /* Detect a race that should no longer be here... */
-	    if ((((SysHrTime) last_tick_count) - ((SysHrTime) ticks)) > 1000) {
-		wrap += LL_LITERAL(1) << 31;
-	    } else {
-		/* 
-		 * XXX Debug: Violates locking order, remove all this,
-		 * after testing!
-		 */
-		erts_dsprintf_buf_t *dsbufp = erts_create_logger_dsbuf();
-		erts_dsprintf(dsbufp, "Did not wrap when last_tick %d "
-			      "and tick %d", 
-			      last_tick_count, ticks);
-		erts_send_error_to_logger_nogl(dsbufp);
-		ticks = last_tick_count;
-	    }
-	}
-	last_tick_count = ticks;
-	res = ((((LONGLONG) ticks) + wrap) * LL_LITERAL(1000000));
-	erts_smp_mtx_unlock(&wrap_lock);
-	return res;
-    }
-}
-
 clock_t 
 sys_times(SysTimes *buffer) {
     clock_t kernel_ticks = (GetTickCount() / 
diff --git a/erts/emulator/test/Makefile b/erts/emulator/test/Makefile
index dfbe47786a..dd2e2cb504 100644
--- a/erts/emulator/test/Makefile
+++ b/erts/emulator/test/Makefile
@@ -108,6 +108,7 @@ MODULES= \
 	trace_call_time_SUITE \
 	scheduler_SUITE \
 	old_scheduler_SUITE \
+	unique_SUITE \
 	z_SUITE \
 	old_mod \
 	long_timers_test \
diff --git a/erts/emulator/test/long_timers_test.erl b/erts/emulator/test/long_timers_test.erl
index 28a4fba9f6..f381332b51 100644
--- a/erts/emulator/test/long_timers_test.erl
+++ b/erts/emulator/test/long_timers_test.erl
@@ -28,7 +28,7 @@
 
 
 -define(MAX_TIMEOUT, 60). % Minutes
--define(MAX_LATE, 10*1000). % Milliseconds
+-define(MAX_LATE_MS, 10*1000). % Milliseconds
 -define(REG_NAME, '___LONG___TIMERS___TEST___SERVER___').
 
 -define(DRV_NAME, timer_driver).
@@ -75,7 +75,7 @@ check_result() ->
 	    erlang:demonitor(Mon),
 	    receive {'DOWN', Mon, _, _, _} -> ok after 0 -> ok end,
 	    stop_node(Node),
-	    check(TORs, (timer:now_diff(End, Start) div 1000) - ?MAX_LATE, ok)
+	    check(TORs, ms((End - Start) - max_late()), ok)
     end.
 
 check([#timeout_rec{timeout = Timeout,
@@ -83,7 +83,7 @@ check([#timeout_rec{timeout = Timeout,
 		    timeout_diff = undefined} | TORs],
       NeedRes,
       _Ok) when Timeout < NeedRes ->
-    io:format("~p timeout = ~p failed! No timeout.~n",
+    io:format("~p timeout = ~p ms failed! No timeout.~n",
 	      [Type, Timeout]),
     check(TORs, NeedRes, failed);
 check([#timeout_rec{timeout_diff = undefined} | TORs],
@@ -95,7 +95,7 @@ check([#timeout_rec{timeout = Timeout,
 		    timeout_diff = {error, Reason}} | TORs],
       NeedRes,
       _Ok) ->
-    io:format("~p timeout = ~p failed! exit reason ~p~n",
+    io:format("~p timeout = ~p ms failed! exit reason ~p~n",
 	      [Type, Timeout, Reason]),
     check(TORs, NeedRes, failed);
 check([#timeout_rec{timeout = Timeout,
@@ -103,43 +103,77 @@ check([#timeout_rec{timeout = Timeout,
 		    timeout_diff = TimeoutDiff} | TORs],
       NeedRes,
       Ok) ->
-    case (0 =< TimeoutDiff) and (TimeoutDiff =< ?MAX_LATE) of
-	true ->
-	    io:format("~p timeout = ~p succeded! timeout diff = ~p.~n",
-		      [Type, Timeout, TimeoutDiff]),
-	    check(TORs, NeedRes, Ok);
-	false ->
-	    io:format("~p timeout = ~p failed! timeout diff = ~p.~n",
-		      [Type, Timeout, TimeoutDiff]),
-	    check(TORs, NeedRes, failed)
-    end;
+    {NewOk, SuccessStr} = case ((0 =< TimeoutDiff)
+				andalso (TimeoutDiff =< max_late())) of
+			      true -> {Ok, "succeeded"};
+			      false -> {failed, "FAILED"}
+			  end,
+    io:format("~s timeout = ~s ms ~s! timeout diff = ~s.~n",
+	      [type_str(Type),
+	       time_str(Timeout),
+	       SuccessStr,
+	       time_str(TimeoutDiff, erlang:convert_time_unit(1, seconds, native))]),
+    check(TORs, NeedRes, NewOk);
 check([], _NeedRes, Ok) ->
     Ok.
 
+type_str(receive_after) -> "receive ... after";
+type_str(bif_timer) -> "BIF timer";
+type_str(driver) -> "driver".
+
+time_str(Time, Unit) ->
+    lists:flatten([time_str(Time), " ", unit_str(Unit)]).
+
+time_str(Time) ->
+    lists:reverse(conv_time_str(lists:reverse(integer_to_list(Time)))).
+
+conv_time_str([X,Y,Z,C|Cs]) when C /= $- ->
+    [X,Y,Z,$`|conv_time_str([C|Cs])];
+conv_time_str(Cs) ->
+    Cs.
+
+unit_str(1) -> "s";
+unit_str(1000) -> "ms";
+unit_str(1000000) -> "us";
+unit_str(1000000000) -> "ns";
+unit_str(Res) when is_integer(Res) -> ["/ ", integer_to_list(Res), " s"];
+unit_str(Res) -> Res.
+
+to_diff(Timeout, Start, Stop) ->
+    %% 'Timeout' in milli seconds
+    %% 'Start', 'Stop', and result in native unit
+    (Stop - Start) - erlang:convert_time_unit(Timeout, milli_seconds, native).
+
+ms(Time) ->
+    erlang:convert_time_unit(Time, native, milli_seconds).
+
+max_late() ->
+    erlang:convert_time_unit(?MAX_LATE_MS, milli_seconds, native).
+
 receive_after(Timeout) ->
-    Start = now(),
+    Start = erlang:monotonic_time(),
     receive
 	{get_result, ?REG_NAME} ->
 	    ?REG_NAME ! #timeout_rec{pid = self(),
 				     type = receive_after,
 				     timeout = Timeout}
     after Timeout ->
-	    Stop = now(),
+	    Stop = erlang:monotonic_time(),
 	    receive
 		{get_result, ?REG_NAME} ->
-	    	    TimeoutDiff = ((timer:now_diff(Stop, Start) div 1000)
-				   - Timeout),
 		    ?REG_NAME ! #timeout_rec{pid = self(),
 					     type = receive_after,
 					     timeout = Timeout,
-					     timeout_diff = TimeoutDiff}
+					     timeout_diff = to_diff(Timeout,
+								    Start,
+								    Stop)}
 	    end
     end.
 
 driver(Timeout) ->
     Port = open_port({spawn, ?DRV_NAME},[]),
     link(Port),
-    Start = now(),
+    Start = erlang:monotonic_time(),
     erlang:port_command(Port, <<?START_TIMER, Timeout:32>>),
     receive
 	{get_result, ?REG_NAME} ->
@@ -147,38 +181,38 @@ driver(Timeout) ->
 				     type = driver,
 				     timeout = Timeout};
 	{Port,{data,[?TIMER]}} ->
-	    Stop = now(),
+	    Stop = erlang:monotonic_time(),
 	    unlink(Port),
 	    true = erlang:port_close(Port),
 	    receive
 		{get_result, ?REG_NAME} ->
-	    	    TimeoutDiff = ((timer:now_diff(Stop, Start) div 1000)
-				   - Timeout),
 		    ?REG_NAME ! #timeout_rec{pid = self(),
 					     type = driver,
 					     timeout = Timeout,
-					     timeout_diff = TimeoutDiff}
+					     timeout_diff = to_diff(Timeout,
+								    Start,
+								    Stop)}
 	    end
     end.
 
 bif_timer(Timeout) ->
     Tmr = erlang:start_timer(Timeout, self(), ok),
-    Start = now(),
+    Start = erlang:monotonic_time(),
     receive
 	{get_result, ?REG_NAME} ->
 	    ?REG_NAME ! #timeout_rec{pid = self(),
 				     type = bif_timer,
 				     timeout = Timeout};
 	{timeout, Tmr, ok} ->
-	    Stop = now(),
+	    Stop = erlang:monotonic_time(),
 	    receive
 		{get_result, ?REG_NAME} ->
-	    	    TimeoutDiff = ((timer:now_diff(Stop, Start) div 1000)
-				   - Timeout),
 		    ?REG_NAME ! #timeout_rec{pid = self(),
 					     type = bif_timer,
 					     timeout = Timeout,
-					     timeout_diff = TimeoutDiff}
+					     timeout_diff = to_diff(Timeout,
+								    Start,
+								    Stop)}
 	    end
     end.
 
@@ -189,7 +223,7 @@ test(Starter, DrvDir, StartDone) ->
     register(?REG_NAME, self()),
     {group_leader, GL} = process_info(whereis(net_kernel),group_leader),
     group_leader(GL, self()),
-    Start = now(),
+    Start = erlang:monotonic_time(),
     TORs = lists:map(fun (Min) ->
 			     TO = Min*60*1000,
 			     [#timeout_rec{pid = spawn_opt(
@@ -222,7 +256,7 @@ test(Starter, DrvDir, StartDone) ->
 test_loop(TORs, Start) ->
     receive
 	{get_result, ?REG_NAME, Pid} ->
-	    End = now(),
+	    End = erlang:monotonic_time(),
 	    Pid ! {result, ?REG_NAME, get_test_results(TORs), Start, End},
 	    erl_ddll:unload_driver(?DRV_NAME),
 	    erl_ddll:stop(),
diff --git a/erts/emulator/test/monitor_SUITE.erl b/erts/emulator/test/monitor_SUITE.erl
index aec59867d8..07e2862b2a 100644
--- a/erts/emulator/test/monitor_SUITE.erl
+++ b/erts/emulator/test/monitor_SUITE.erl
@@ -26,7 +26,8 @@
 	 case_1/1, case_1a/1, case_2/1, case_2a/1, mon_e_1/1, demon_e_1/1, demon_1/1,
 	 demon_2/1, demon_3/1, demonitor_flush/1,
 	 local_remove_monitor/1, remote_remove_monitor/1, mon_1/1, mon_2/1,
-	 large_exit/1, list_cleanup/1, mixer/1, named_down/1, otp_5827/1]).
+	 large_exit/1, list_cleanup/1, mixer/1, named_down/1, otp_5827/1,
+	 monitor_time_offset/1]).
 
 -export([init_per_testcase/2, end_per_testcase/2]).
 
@@ -38,7 +39,8 @@ all() ->
     [case_1, case_1a, case_2, case_2a, mon_e_1, demon_e_1,
      demon_1, mon_1, mon_2, demon_2, demon_3,
      demonitor_flush, {group, remove_monitor}, large_exit,
-     list_cleanup, mixer, named_down, otp_5827].
+     list_cleanup, mixer, named_down, otp_5827,
+     monitor_time_offset].
 
 groups() -> 
     [{remove_monitor, [],
@@ -59,7 +61,7 @@ end_per_group(_GroupName, Config) ->
 
 init_per_testcase(Func, Config) when is_atom(Func), is_list(Config) ->
     Dog=?t:timetrap(?t:minutes(15)),
-    [{watchdog, Dog}|Config].
+    [{watchdog, Dog},{testcase, Func}|Config].
 
 end_per_testcase(_Func, Config) ->
     Dog=?config(watchdog, Config),
@@ -837,6 +839,89 @@ otp_5827(Config) when is_list(Config) ->
 		  ?line ?t:fail("erlang:monitor/2 hangs")
 	  end.
 
+monitor_time_offset(Config) when is_list(Config) ->
+    {ok, Node} = start_node(Config, "+C single_time_warp"),
+    Me = self(),
+    PMs = lists:map(fun (_) ->
+			    Pid = spawn(Node,
+					fun () ->
+						check_monitor_time_offset(Me)
+					end),
+			    {Pid, erlang:monitor(process, Pid)}
+		    end,
+		    lists:seq(1, 100)),
+    lists:foreach(fun ({P, _M}) ->
+			  P ! check_no_change_message
+		  end, PMs),
+    lists:foreach(fun ({P, M}) ->
+			  receive
+			      {no_change_message_received, P} ->
+				  ok;
+			      {'DOWN', M, process, P, Reason} ->
+				  ?t:fail(Reason)
+			  end
+		  end, PMs),
+    preliminary = rpc:call(Node, erlang, system_flag, [time_offset, finalize]),
+    lists:foreach(fun ({P, M}) ->
+			  receive
+			      {change_messages_received, P} ->
+				  erlang:demonitor(M, [flush]);
+			      {'DOWN', M, process, P, Reason} ->
+				  ?t:fail(Reason)
+			  end
+		  end, PMs),
+    stop_node(Node),
+    ok.
+
+check_monitor_time_offset(Leader) ->
+    Mon1 = erlang:monitor(time_offset, clock_service),
+    Mon2 = erlang:monitor(time_offset, clock_service),
+    Mon3 = erlang:monitor(time_offset, clock_service),
+    Mon4 = erlang:monitor(time_offset, clock_service),
+
+    erlang:demonitor(Mon2, [flush]),
+    
+    Mon5 = erlang:monitor(time_offset, clock_service),
+    Mon6 = erlang:monitor(time_offset, clock_service),
+    Mon7 = erlang:monitor(time_offset, clock_service),
+
+    receive check_no_change_message -> ok end,
+    receive
+	{'CHANGE', _, time_offset, clock_service, _} ->
+	    exit(unexpected_change_message_received)
+    after 0 ->
+	    Leader ! {no_change_message_received, self()}
+    end,
+    receive after 100 -> ok end,
+    erlang:demonitor(Mon4, [flush]),
+    receive
+	{'CHANGE', Mon3, time_offset, clock_service, _} ->
+	    ok
+    end,
+    receive
+	{'CHANGE', Mon6, time_offset, clock_service, _} ->
+	    ok
+    end,
+    erlang:demonitor(Mon5, [flush]),
+    receive
+	{'CHANGE', Mon7, time_offset, clock_service, _} ->
+	    ok
+    end,
+    receive
+	{'CHANGE', Mon1, time_offset, clock_service, _} ->
+	    ok
+    end,
+    receive
+	{'CHANGE', _, time_offset, clock_service, _} ->
+	    exit(unexpected_change_message_received)
+    after 1000 ->
+	    ok
+    end,
+    Leader ! {change_messages_received, self()}.
+
+%%
+%% ...
+%%
 
 wait_for_m(_,_,0) ->
     exit(monitor_wait_timeout);
@@ -959,3 +1044,25 @@ generate(_Fun, 0) ->
     [];
 generate(Fun, N) ->
     [Fun() | generate(Fun, N-1)].
+
+start_node(Config) ->
+    start_node(Config, "").
+
+start_node(Config, Args) ->
+    TestCase = ?config(testcase, Config),
+    PA = filename:dirname(code:which(?MODULE)),
+    ESTime = erlang:monotonic_time(1) + erlang:time_offset(1),
+    Unique = erlang:unique_integer([positive]),
+    Name = list_to_atom(atom_to_list(?MODULE)
+			++ "-"
+			++ atom_to_list(TestCase)
+			++ "-"
+			++ integer_to_list(ESTime)
+			++ "-"
+			++ integer_to_list(Unique)),
+    test_server:start_node(Name,
+			   slave,
+			   [{args, "-pa " ++ PA ++ " " ++ Args}]).
+
+stop_node(Node) ->
+    test_server:stop_node(Node).
diff --git a/erts/emulator/test/time_SUITE.erl b/erts/emulator/test/time_SUITE.erl
index a0a8a9c42c..43f7ac7f7c 100644
--- a/erts/emulator/test/time_SUITE.erl
+++ b/erts/emulator/test/time_SUITE.erl
@@ -34,7 +34,14 @@
 	 bad_univ_to_local/1, bad_local_to_univ/1,
 	 univ_to_seconds/1, seconds_to_univ/1,
 	 consistency/1,
-	 now_unique/1, now_update/1, timestamp/1]).
+	 now_unique/1, now_update/1, timestamp/1,
+	 time_warp_modes/1,
+	 monotonic_time_monotonicity/1,
+	 time_unit_conversion/1,
+	 signed_time_unit_conversion/1,
+	 erlang_timestamp/1]).
+
+-export([init_per_testcase/2, end_per_testcase/2]).
 
 -export([local_to_univ_utc/1]).
 
@@ -56,6 +63,12 @@
 
 -define(dst_timezone, 2).
 
+init_per_testcase(Func, Config) when is_atom(Func), is_list(Config) ->
+    [{testcase, Func}|Config].
+
+end_per_testcase(_Func, Config) ->
+    ok.
+
 suite() -> [{ct_hooks,[ts_install_cth]}].
 
 all() -> 
@@ -63,7 +76,12 @@ all() ->
      bad_univ_to_local, bad_local_to_univ, 
      univ_to_seconds, seconds_to_univ,
      consistency,
-     {group, now}, timestamp].
+     {group, now}, timestamp,
+     time_warp_modes,
+     monotonic_time_monotonicity,
+     time_unit_conversion,
+     signed_time_unit_conversion,
+     erlang_timestamp].
 
 groups() -> 
     [{now, [], [now_unique, now_update]}].
@@ -420,6 +438,368 @@ now_update1(N) when N > 0 ->
 now_update1(0) ->
     ?line test_server:fail().
 
+time_warp_modes(Config) when is_list(Config) ->
+    %% All time warp modes always supported in
+    %% combination with no time correction...
+    check_time_warp_mode(Config, false, no_time_warp),
+    check_time_warp_mode(Config, false, single_time_warp),
+    check_time_warp_mode(Config, false, multi_time_warp),
+
+    erts_debug:set_internal_state(available_internal_state, true),
+    try
+	case erts_debug:get_internal_state({check_time_config,
+					    true, no_time_warp}) of
+	    false -> ok;
+	    true -> check_time_warp_mode(Config, true, no_time_warp)
+	end,
+	case erts_debug:get_internal_state({check_time_config,
+					    true, single_time_warp}) of
+	    false -> ok;
+	    true -> check_time_warp_mode(Config, true, single_time_warp)
+	end,
+	case erts_debug:get_internal_state({check_time_config,
+					    true, multi_time_warp}) of
+	    false -> ok;
+	    true -> check_time_warp_mode(Config, true, multi_time_warp)
+	end
+    after
+	erts_debug:set_internal_state(available_internal_state, false)
+    end.
+
+check_time_warp_mode(Config, TimeCorrection, TimeWarpMode) ->
+    io:format("~n~n~n***** Testing TimeCorrection=~p TimeWarpMode=~p *****~n",
+	      [TimeCorrection, TimeWarpMode]),
+    Mon = erlang:monitor(time_offset, clock_service),
+    _ = erlang:time_offset(),
+    Start = erlang:monotonic_time(1000),
+    MonotonicityTimeout = 2000,
+    {ok, Node} = start_node(Config,
+			    "+c " ++ atom_to_list(TimeCorrection)
+			    ++ " +C " ++ atom_to_list(TimeWarpMode)),
+    StartTime = rpc:call(Node, erlang, system_info, [start_time]),
+    Me = self(),
+    MonotincityTestStarted = make_ref(),
+    MonotincityTestDone = make_ref(),
+    spawn_link(Node,
+	       fun () ->
+		       Me ! MonotincityTestStarted,
+		       cmp_times(erlang:start_timer(MonotonicityTimeout,
+						    self(),
+						    timeout),
+				 erlang:monotonic_time()),
+		       Me ! MonotincityTestDone
+	       end),
+    receive MonotincityTestStarted -> ok end,
+    check_time_offset(Node, TimeWarpMode),
+    TimeWarpMode = rpc:call(Node, erlang, system_info, [time_warp_mode]),
+    TimeCorrection = rpc:call(Node, erlang, system_info, [time_correction]),
+    receive MonotincityTestDone -> ok end,
+    MonotonicTime = rpc:call(Node, erlang, monotonic_time, []),
+    MonotonicTimeUnit = rpc:call(Node,
+				       erlang,
+				       convert_time_unit,
+				       [1, seconds, native]),
+    UpMilliSeconds = erlang:convert_time_unit(MonotonicTime - StartTime,
+					      MonotonicTimeUnit,
+					      milli_seconds),
+    io:format("UpMilliSeconds=~p~n", [UpMilliSeconds]),
+    End = erlang:monotonic_time(milli_seconds),
+    stop_node(Node),
+    try
+	true = (UpMilliSeconds > (98*MonotonicityTimeout) div 100),
+	true = (UpMilliSeconds < (102*(End-Start)) div 100)
+    catch
+	error:_ ->
+	    io:format("Uptime inconsistency", []),
+	    case {TimeCorrection, erlang:system_info(time_correction)} of
+		{true, true} ->
+		    ?t:fail(uptime_inconsistency);
+		{true, false} ->
+		    _ = erlang:time_offset(),
+		    receive
+			{'CHANGE', Mon, time_offset, clock_service, _} ->
+			    ignore
+		    after 1000 ->
+			    ?t:fail(uptime_inconsistency)
+		    end;
+		_ ->
+		    ignore
+	    end
+    end,
+    erlang:demonitor(Mon, [flush]),
+    ok.
+
+check_time_offset(Node, no_time_warp) ->
+    final = rpc:call(Node, erlang, system_info, [time_offset]),
+    final = rpc:call(Node, erlang, system_flag, [time_offset, finalize]),
+    final = rpc:call(Node, erlang, system_info, [time_offset]);
+check_time_offset(Node, single_time_warp) ->
+    preliminary = rpc:call(Node, erlang, system_info, [time_offset]),
+    preliminary = rpc:call(Node, erlang, system_flag, [time_offset, finalize]),
+    final = rpc:call(Node, erlang, system_info, [time_offset]),
+    final = rpc:call(Node, erlang, system_flag, [time_offset, finalize]);
+check_time_offset(Node, multi_time_warp) ->
+    volatile = rpc:call(Node, erlang, system_info, [time_offset]),
+    volatile = rpc:call(Node, erlang, system_flag, [time_offset, finalize]),
+    volatile = rpc:call(Node, erlang, system_info, [time_offset]).
+
+monotonic_time_monotonicity(Config) when is_list(Config) ->
+    Done = erlang:start_timer(10000,self(),timeout),
+    cmp_times(Done, erlang:monotonic_time()).
+
+cmp_times(Done, X0) ->
+    X1 = erlang:monotonic_time(),
+    X2 = erlang:monotonic_time(),
+    X3 = erlang:monotonic_time(),
+    X4 = erlang:monotonic_time(),
+    X5 = erlang:monotonic_time(),
+    true = (X0 =< X1),
+    true = (X1 =< X2),
+    true = (X2 =< X3),
+    true = (X3 =< X4),
+    true = (X4 =< X5),
+    receive
+	{timeout, Done, timeout} ->
+	    ok
+    after 0 ->
+	    cmp_times(Done, X5)
+    end.
+
+-define(CHK_RES_CONVS_TIMEOUT, 400).
+
+time_unit_conversion(Config) when is_list(Config) ->
+    Mon = erlang:monitor(time_offset, clock_service),
+    start_check_res_convs(Mon, 1000000000000),
+    start_check_res_convs(Mon, 2333333333333),
+    start_check_res_convs(Mon, 5732678356789),
+    erlang:demonitor(Mon, [flush]).
+    
+start_check_res_convs(Mon, Res) ->
+    io:format("Checking ~p time_unit~n", [Res]),
+    check_res_convs(Mon,
+		    erlang:start_timer(?CHK_RES_CONVS_TIMEOUT,
+				       self(),
+				       timeout),
+		    Res).
+    
+
+check_res_convs(Mon, Done, Res) ->
+    receive
+	{timeout, Done, timeout} ->
+	    case Res div 10 of
+		0 ->
+		    ok;
+		NewRes ->
+		    start_check_res_convs(Mon, NewRes)
+	    end
+    after 0 ->
+	    do_check_res_convs(Mon, Done, Res)
+    end.
+
+do_check_res_convs(Mon, Done, Res) ->
+    TStart = erlang:monotonic_time(),
+    T = erlang:monotonic_time(Res),
+    TEnd = erlang:monotonic_time(),
+    TMin = erlang:convert_time_unit(TStart, native, Res),
+    TMax = erlang:convert_time_unit(TEnd, native, Res),
+    %io:format("~p =< ~p =< ~p~n", [TMin, T, TEnd]),
+    true = (TMin =< T),
+    true = (TMax >= T),
+    check_time_offset_res_conv(Mon, Res),
+    check_res_convs(Mon, Done, Res).
+
+
+check_time_offset_res_conv(Mon, Res) ->
+    TORes = erlang:time_offset(Res),
+    TO = erlang:time_offset(),
+    case erlang:convert_time_unit(TO, native, Res) of
+	TORes ->
+	    ok;
+	TORes2 ->
+	    case check_time_offset_change(Mon, TO, 1000) of
+		{TO, false} ->
+		    ?t:fail({time_unit_conversion_inconsistency,
+			     TO, TORes, TORes2});
+		{_NewTO, true} ->
+		    ?t:format("time_offset changed", []),
+		    check_time_offset_res_conv(Mon, Res)
+	    end
+    end.
+
+signed_time_unit_conversion(Config) when is_list(Config) ->
+    chk_strc(1000000000, 1000000),
+    chk_strc(1000000000, 1000),
+    chk_strc(1000000000, 1),
+    chk_strc(1000000, 1000),
+    chk_strc(1000000, 1),
+    chk_strc(1000, 1),
+    chk_strc(4711, 17),
+    chk_strc(1 bsl 10, 1),
+    chk_strc(1 bsl 16, 10),
+    chk_strc(1 bsl 17, 1 bsl 8),
+    chk_strc((1 bsl 17) + 1, (1 bsl 8) - 1),
+    chk_strc(1 bsl 17, 11),
+    ok.
+
+chk_strc(Res0, Res1) ->
+    case (Res0 /= Res1) andalso (Res0 =< 1000000) andalso (Res1 =< 1000000) of
+	true ->
+	    {FromRes, ToRes} = case Res0 > Res1 of
+				   true -> {Res0, Res1};
+				   false -> {Res1, Res0}
+			       end,
+	    MinFromValuesPerToValue = FromRes div ToRes,
+	    MaxFromValuesPerToValue = ((FromRes-1) div ToRes)+1,
+	    io:format("~p -> ~p [~p, ~p]~n",
+		      [FromRes, ToRes,
+		       MinFromValuesPerToValue, MaxFromValuesPerToValue]),
+	    chk_values_per_value(FromRes, ToRes,
+				 -10*FromRes, 10*FromRes,
+				 MinFromValuesPerToValue,
+				 MaxFromValuesPerToValue,
+				 undefined, MinFromValuesPerToValue);
+	_ ->
+	    ok
+    end,
+    chk_random_values(Res0, Res1),
+    chk_random_values(Res1, Res0),
+    ok.
+
+chk_random_values(FR, TR) ->
+%    case (FR rem TR == 0) orelse (TR rem FR == 0) of
+%	true ->
+	    io:format("rand values ~p -> ~p~n", [FR, TR]),
+	    random:seed(268438039, 268440479, 268439161),
+	    Values = lists:map(fun (_) -> random:uniform(1 bsl 65) - (1 bsl 64) end,
+			       lists:seq(1, 100000)),
+	    CheckFun = fun (V) ->
+			       CV = erlang:convert_time_unit(V, FR, TR),
+			       case {(FR*CV) div TR =< V,
+				     (FR*(CV+1)) div TR >= V} of
+				   {true, true} ->
+				       ok;
+				   Failure ->
+				       ?t:fail({Failure, CV, V, FR, TR})
+			       end
+		       end,
+	    lists:foreach(CheckFun, Values).%;
+%	false -> ok
+%    end.
+		       
+
+chk_values_per_value(_FromRes, _ToRes,
+	 EndValue, EndValue,
+	 MinFromValuesPerToValue, MaxFromValuesPerToValue,
+	 _ToValue, FromValueCount) ->
+%    io:format("~p [~p]~n", [EndValue, FromValueCount]),
+    case ((MinFromValuesPerToValue =< FromValueCount)
+	  andalso (FromValueCount =< MaxFromValuesPerToValue)) of
+	false ->
+	    ?t:fail({MinFromValuesPerToValue,
+		     FromValueCount,
+		     MaxFromValuesPerToValue});
+	true ->
+	    ok
+    end;
+chk_values_per_value(FromRes, ToRes, Value, EndValue,
+		     MinFromValuesPerToValue, MaxFromValuesPerToValue,
+		     ToValue, FromValueCount) ->
+    case erlang:convert_time_unit(Value, FromRes, ToRes) of
+	ToValue ->
+	    chk_values_per_value(FromRes, ToRes,
+				 Value+1, EndValue,
+				 MinFromValuesPerToValue,
+				 MaxFromValuesPerToValue,
+				 ToValue, FromValueCount+1);
+	NewToValue ->
+	    case ((MinFromValuesPerToValue =< FromValueCount)
+		  andalso (FromValueCount =< MaxFromValuesPerToValue)) of
+		false ->
+		    ?t:fail({MinFromValuesPerToValue,
+			     FromValueCount,
+			     MaxFromValuesPerToValue});
+		true ->
+%		    io:format("~p -> ~p [~p]~n",
+%			      [Value, NewToValue, FromValueCount]),
+		    chk_values_per_value(FromRes, ToRes,
+					 Value+1, EndValue,
+					 MinFromValuesPerToValue,
+					 MaxFromValuesPerToValue,
+					 NewToValue, 1)
+	    end
+    end.
+
+erlang_timestamp(Config) when is_list(Config) ->
+    Mon = erlang:monitor(time_offset, clock_service),
+    {TO, _} = check_time_offset_change(Mon,
+				       erlang:time_offset(),
+				       0),
+    Done = erlang:start_timer(10000,self(),timeout),
+    ok = check_erlang_timestamp(Done, Mon, TO).
+
+check_erlang_timestamp(Done, Mon, TO) ->
+    receive
+	{timeout, Done, timeout} ->
+	    erlang:demonitor(Mon, [flush]),
+	    ok
+    after 0 ->
+	    do_check_erlang_timestamp(Done, Mon, TO)
+    end.
+
+do_check_erlang_timestamp(Done, Mon, TO) ->
+    MinMon = erlang:monotonic_time(),
+    {MegaSec, Sec, MicroSec} = erlang:timestamp(),
+    MaxMon = erlang:monotonic_time(),
+    TsMin = erlang:convert_time_unit(MinMon+TO,
+				     native,
+				     micro_seconds),
+    TsMax = erlang:convert_time_unit(MaxMon+TO,
+				     native,
+				     micro_seconds),
+    TsTime = (MegaSec*1000000+Sec)*1000000+MicroSec,
+    case (TsMin =< TsTime) andalso (TsTime =< TsMax) of
+	true ->
+	    NewTO = case erlang:time_offset() of
+			TO ->
+			    TO;
+			_ ->
+			    check_time_offset_change(Mon, TO, 0)
+		    end,
+	    check_erlang_timestamp(Done, Mon, NewTO);
+	false ->
+	    io:format("TsMin=~p TsTime=~p TsMax=~p~n", [TsMin, TsTime, TsMax]),
+	    ?t:format("Detected inconsistency; "
+		      "checking for time_offset change...", []),
+	    case check_time_offset_change(Mon, TO, 1000) of
+		{TO, false} ->
+		    ?t:fail(timestamp_inconsistency);
+		{NewTO, true} ->
+		    ?t:format("time_offset changed", []),
+		    check_erlang_timestamp(Done, Mon, NewTO)
+	    end
+    end.
+
+check_time_offset_change(Mon, TO, Wait) ->
+    process_changed_time_offset(Mon, TO, false, Wait).
+
+process_changed_time_offset(Mon, TO, Changed, Wait) ->
+    receive
+	{'CHANGE', Mon, time_offset, clock_service, NewTO} ->
+	    process_changed_time_offset(Mon, NewTO, true, Wait)
+    after Wait ->
+	    case erlang:time_offset() of
+		TO ->
+		    {TO, Changed};
+		_OtherTO ->
+		    receive
+			{'CHANGE', Mon, time_offset, clock_service, NewTO} ->
+			    process_changed_time_offset(Mon, NewTO, true, Wait)
+		    end
+	    end
+    end.
+    
+
+
 %% Returns the test data: a list of {Utc, Local} tuples.
 
 test_data() ->
@@ -554,4 +934,25 @@ bad_dates() ->
 
      {{1996, 4, 30}, {12, 0, -1}},		% Sec
      {{1996, 4, 30}, {12, 0, 60}}].
-     
+
+start_node(Config) ->
+    start_node(Config, "").
+
+start_node(Config, Args) ->
+    TestCase = ?config(testcase, Config),
+    PA = filename:dirname(code:which(?MODULE)),
+    ESTime = erlang:monotonic_time(1) + erlang:time_offset(1),
+    Unique = erlang:unique_integer([positive]),
+    Name = list_to_atom(atom_to_list(?MODULE)
+			++ "-"
+			++ atom_to_list(TestCase)
+			++ "-"
+			++ integer_to_list(ESTime)
+			++ "-"
+			++ integer_to_list(Unique)),
+    test_server:start_node(Name,
+			   slave,
+			   [{args, "-pa " ++ PA ++ " " ++ Args}]).
+
+stop_node(Node) ->
+    test_server:stop_node(Node).
diff --git a/erts/emulator/test/unique_SUITE.erl b/erts/emulator/test/unique_SUITE.erl
new file mode 100644
index 0000000000..5ad6e59272
--- /dev/null
+++ b/erts/emulator/test/unique_SUITE.erl
@@ -0,0 +1,390 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2014. All Rights Reserved.
+%% 
+%% The contents of this file are subject to the Erlang Public License,
+%% Version 1.1, (the "License"); you may not use this file except in
+%% compliance with the License. You should have received a copy of the
+%% Erlang Public License along with this software. If not, it can be
+%% retrieved online at http://www.erlang.org/.
+%% 
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and limitations
+%% under the License.
+%% 
+%% %CopyrightEnd%
+%%
+
+-module(unique_SUITE).
+
+-export([all/0, suite/0,groups/0,init_per_suite/1, end_per_suite/1, 
+	 init_per_group/2,end_per_group/2,
+	 init_per_testcase/2,end_per_testcase/2]).
+-export([unique_monotonic_integer_white_box/1,
+	 unique_integer_white_box/1]).
+
+-include_lib("test_server/include/test_server.hrl").
+
+%-define(P(V), V).
+-define(P(V), print_ret_val(?FILE, ?LINE, V)).
+
+-define(PRINT(V), print_ret_val(?FILE, ?LINE, V)).
+
+
+init_per_testcase(Case, Config) ->
+    ?line Dog=test_server:timetrap(test_server:minutes(2)),
+    [{watchdog, Dog}, {testcase, Case}|Config].
+
+end_per_testcase(_, Config) ->
+    Dog=?config(watchdog, Config),
+    test_server:timetrap_cancel(Dog),
+    ok.
+
+suite() -> [{ct_hooks,[ts_install_cth]}].
+
+all() -> 
+    [unique_monotonic_integer_white_box,
+     unique_integer_white_box].
+
+groups() -> 
+    [].
+
+init_per_suite(Config) ->
+    erts_debug:set_internal_state(available_internal_state, true),
+    Config.
+
+end_per_suite(_Config) ->
+    erts_debug:set_internal_state(available_internal_state, false),
+    ok.
+
+init_per_group(_GroupName, Config) ->
+    Config.
+
+end_per_group(_GroupName, Config) ->
+    Config.
+
+%%
+%%
+%% Unique counter white box test case
+%%
+%%
+
+unique_monotonic_integer_white_box(Config) when is_list(Config) ->
+    {ok, Node} = start_node(Config),
+    TestServer = self(),
+    Success = make_ref(),
+    %% Run this in a separate node, so we don't mess up
+    %% the system when moving the strict monotonic counter
+    %% around in a non-strict monotonic way...
+    Test = spawn(Node,
+		 fun () ->
+			 unique_monotonic_integer_white_box_test(TestServer, Success)
+		 end),
+    Mon = erlang:monitor(process, Test),
+    receive
+	{'DOWN', Mon, process, Test, Error} ->
+	    ?t:fail(Error);
+	Success ->
+	    ok
+    end,
+    erlang:demonitor(Mon, [flush]),
+    stop_node(Node),
+    ok.
+
+set_unique_monotonic_integer_state(MinCounter, NextValue) ->
+    true = erts_debug:set_internal_state(unique_monotonic_integer_state,
+					 NextValue-MinCounter-1).
+    
+    
+
+unique_monotonic_integer_white_box_test(TestServer, Success) ->
+    erts_debug:set_internal_state(available_internal_state, true),
+
+    WordSize = erlang:system_info({wordsize, internal}),
+    SmallBits = WordSize*8 - 4,
+
+    MinSmall = -1*(1 bsl (SmallBits-1)),
+    MaxSmall = (1 bsl (SmallBits-1))-1,
+    %% Make sure we got small sizes correct...
+    0 = erts_debug:size(MinSmall),
+    false = 0 =:= erts_debug:size(MinSmall-1),
+    0 = erts_debug:size(MaxSmall),
+    false = 0 =:= erts_debug:size(MaxSmall+1),
+
+    ?PRINT({min_small, MinSmall}),
+    ?PRINT({max_small, MaxSmall}),
+
+    MinSint64 = -1*(1 bsl 63),
+    MaxSint64 = (1 bsl 63)-1,
+
+    ?PRINT({min_Sint64, MinSint64}),
+    ?PRINT({max_Sint64, MaxSint64}),
+
+    MinCounter = erts_debug:get_internal_state(min_unique_monotonic_integer),
+    MaxCounter = MinCounter + (1 bsl 64) - 1,
+
+    ?PRINT({min_counter, MinCounter}),
+    ?PRINT({max_counter, MaxCounter}),
+
+    case WordSize of
+	4 ->
+	    MinCounter = MinSint64;
+	8 ->
+	    MinCounter = MinSmall
+    end,
+
+    StartState = erts_debug:get_internal_state(unique_monotonic_integer_state),
+
+    %% Verify that we get expected results over all internal limits...
+
+    case MinCounter < MinSmall of
+	false ->
+	    8 = WordSize,
+	    ok;
+	true ->
+	    4 = WordSize,
+	    ?PRINT(over_min_small),
+	    set_unique_monotonic_integer_state(MinCounter, MinSmall-2),
+	    true = (?P(erlang:unique_integer([monotonic])) == MinSmall - 2),
+	    true = (?P(erlang:unique_integer([monotonic])) == MinSmall - 1),
+	    true = (?P(erlang:unique_integer([monotonic])) == MinSmall),
+	    true = (?P(erlang:unique_integer([monotonic]))  == MinSmall + 1),
+	    true = (?P(erlang:unique_integer([monotonic]))  == MinSmall + 2),
+	    garbage_collect(),
+	    ok
+    end,
+
+    ?PRINT(over_zero), %% Not really an interesting limit, but...
+    set_unique_monotonic_integer_state(MinCounter, -2),
+    true = (?P(erlang:unique_integer([monotonic])) == -2),
+    true = (?P(erlang:unique_integer([monotonic])) == -1),
+    true = (?P(erlang:unique_integer([monotonic])) == 0),
+    true = (?P(erlang:unique_integer([monotonic]))  == 1),
+    true = (?P(erlang:unique_integer([monotonic]))  == 2),
+    garbage_collect(),
+
+    ?PRINT(over_max_small),
+    set_unique_monotonic_integer_state(MinCounter, MaxSmall-2),
+    true = (?P(erlang:unique_integer([monotonic])) == MaxSmall - 2),
+    true = (?P(erlang:unique_integer([monotonic])) == MaxSmall - 1),
+    true = (?P(erlang:unique_integer([monotonic])) == MaxSmall),
+    true = (?P(erlang:unique_integer([monotonic]))  == MaxSmall + 1),
+    true = (?P(erlang:unique_integer([monotonic]))  == MaxSmall + 2),
+    garbage_collect(),
+
+    case MaxCounter > MaxSint64 of
+	false ->
+	    4 = WordSize,
+	    ok;
+	true ->
+	    8 = WordSize,
+	    ?PRINT(over_max_sint64),
+	    set_unique_monotonic_integer_state(MinCounter, MaxSint64-2),
+	    true = (?P(erlang:unique_integer([monotonic])) == MaxSint64 - 2),
+	    true = (?P(erlang:unique_integer([monotonic])) == MaxSint64 - 1),
+	    true = (?P(erlang:unique_integer([monotonic])) == MaxSint64),
+	    true = (?P(erlang:unique_integer([monotonic])) == MaxSint64 + 1),
+	    true = (?P(erlang:unique_integer([monotonic])) == MaxSint64 + 2),
+	    garbage_collect()
+    end,
+
+    ?PRINT(over_max_min_counter),
+    set_unique_monotonic_integer_state(MinCounter, if MaxCounter == MaxSint64 ->
+							   MaxCounter-2;
+						      true ->
+							   MinCounter-3
+						   end),
+    true = (?P(erlang:unique_integer([monotonic])) == MaxCounter - 2),
+    true = (?P(erlang:unique_integer([monotonic])) == MaxCounter - 1),
+    true = (?P(erlang:unique_integer([monotonic])) == MaxCounter),
+    true = (?P(erlang:unique_integer([monotonic])) == MinCounter),
+    true = (?P(erlang:unique_integer([monotonic])) == MinCounter + 1),
+    true = (?P(erlang:unique_integer([monotonic])) == MinCounter + 2),
+    garbage_collect(),
+
+    %% Restore initial state and hope we didn't mess it up for the
+    %% system...
+    true = erts_debug:set_internal_state(unique_monotonic_integer_state,
+					 StartState),
+
+    TestServer ! Success.
+
+%%
+%%
+%% Unique integer white box test case
+%%
+%%
+
+-record(uniqint_info, {min_int,
+		       max_int,
+		       max_small,
+		       schedulers,
+		       sched_bits}).
+
+unique_integer_white_box(Config) when is_list(Config) ->
+    UinqintInfo = init_uniqint_info(),
+    #uniqint_info{min_int = MinInt,
+		  max_int = MaxInt,
+		  max_small = MaxSmall} = UinqintInfo,
+    io:format("****************************************************~n", []),
+    io:format("*** Around MIN_UNIQ_INT ~p ***~n", [MinInt]),
+    io:format("****************************************************~n", []),
+    check_unique_integer_around(MinInt, UinqintInfo),
+    io:format("****************************************************~n", []),
+    io:format("*** Around 0 ***~n", []),
+    io:format("****************************************************~n", []),
+    check_unique_integer_around(0, UinqintInfo),
+    io:format("****************************************************~n", []),
+    io:format("*** Around MAX_SMALL ~p ***~n", [MaxSmall]),
+    io:format("****************************************************~n", []),
+    check_unique_integer_around(MaxSmall, UinqintInfo),
+    io:format("****************************************************~n", []),
+    io:format("*** Around 2^64+MIN_UNIQ_INT ~p ***~n", [(1 bsl 64)+MinInt]),
+    io:format("****************************************************~n", []),
+    check_unique_integer_around((1 bsl 64)+MinInt, UinqintInfo),
+    io:format("****************************************************~n", []),
+    io:format("*** Around 2^64 ~p~n", [(1 bsl 64)]),
+    io:format("****************************************************~n", []),
+    check_unique_integer_around((1 bsl 64), UinqintInfo),
+    io:format("****************************************************~n", []),
+    io:format("*** Around 2^64-MIN_UNIQ_INT ~p ***~n", [(1 bsl 64)-MinInt]),
+    io:format("****************************************************~n", []),
+    check_unique_integer_around((1 bsl 64)-MinInt, UinqintInfo),
+    io:format("****************************************************~n", []),
+    io:format("*** Around MAX_UNIQ_INT ~p ***~n", [MaxInt]),
+    io:format("****************************************************~n", []),
+    check_unique_integer_around(MaxInt, UinqintInfo),
+    ok.
+	
+
+%%% Internal unique_integer_white_box/1 test case
+
+calc_sched_bits(NoScheds, Shift) when NoScheds < 1 bsl Shift ->
+    Shift;
+calc_sched_bits(NoScheds, Shift) ->
+    calc_sched_bits(NoScheds, Shift+1).
+
+init_uniqint_info() ->
+    SmallBits = erlang:system_info({wordsize, internal})*8-4,
+    io:format("SmallBits=~p~n", [SmallBits]),
+    Schedulers = erlang:system_info(schedulers),
+    io:format("Schedulers=~p~n", [Schedulers]),
+    MinSmall = -1*(1 bsl (SmallBits-1)),
+    io:format("MinSmall=~p~n", [MinSmall]),
+    MaxSmall = (1 bsl (SmallBits-1))-1,
+    io:format("MaxSmall=~p~n", [MaxSmall]),
+    SchedBits = calc_sched_bits(Schedulers, 0),
+    io:format("SchedBits=~p~n", [SchedBits]),
+    MaxInt = ((((1 bsl 64) - 1) bsl SchedBits) bor Schedulers) + MinSmall,
+    io:format("MaxInt=~p~n", [MaxInt]),
+    #uniqint_info{min_int = MinSmall,
+		  max_int = MaxInt,
+		  max_small = MaxSmall,
+		  schedulers = Schedulers,
+		  sched_bits = SchedBits}.
+
+valid_uniqint(Int, #uniqint_info{min_int = MinInt} = UinqintInfo) when Int < MinInt ->
+    valid_uniqint(MinInt, UinqintInfo);
+valid_uniqint(Int, #uniqint_info{min_int = MinInt,
+				 sched_bits = SchedBits,
+				 schedulers = Scheds}) ->
+    Int1 = Int - MinInt,
+    {Inc, ThreadNo} = case Int1 band ((1 bsl SchedBits) - 1) of
+			  TN when TN > Scheds ->
+			      {1, Scheds};
+			  TN ->
+			      {0, TN}
+		      end,
+    Counter = ((Int1 bsr SchedBits) + Inc) rem (1 bsl 64),
+    ((Counter bsl SchedBits) bor ThreadNo) + MinInt.
+
+smaller_valid_uniqint(Int, UinqintInfo) ->
+    Cand = Int-1,
+    case valid_uniqint(Cand, UinqintInfo) of
+	RI when RI < Int ->
+	    RI;
+	_ ->
+	    smaller_valid_uniqint(Cand, UinqintInfo)
+    end.
+
+int32_to_bigendian_list(Int) ->
+    0 = Int bsr 32,
+    [(Int bsr 24) band 16#ff,
+     (Int bsr 16) band 16#ff,
+     (Int bsr 8) band 16#ff,
+     Int band 16#ff].
+
+mk_uniqint(Int, #uniqint_info {min_int = MinInt,
+			       sched_bits = SchedBits} = _UinqintInfo) ->
+    Int1 = Int - MinInt,
+    ThrId = Int1 band ((1 bsl SchedBits) - 1),
+    Value = (Int1 bsr SchedBits) band ((1 bsl 64) - 1),
+    0 = Int1 bsr (SchedBits + 64),
+    NodeName = atom_to_list(node()),
+    Make = {make_unique_integer, ThrId, Value},
+    %% erlang:display(Make),
+    Res = erts_debug:get_internal_state(Make),
+    %% erlang:display({uniq_int, Res}),
+    Res.
+
+check_uniqint(Int, UinqintInfo) ->
+    UniqInt = mk_uniqint(Int, UinqintInfo),
+    io:format("UniqInt=~p ", [UniqInt]),
+    case UniqInt =:= Int of
+	true ->
+	    io:format("OK~n~n", []);
+	false ->
+	    io:format("result UniqInt=~p FAILED~n", [UniqInt]),
+	    exit(badres)
+    end.
+
+check_unique_integer_around(Int, #uniqint_info{min_int = MinInt,
+					       max_int = MaxInt} = UinqintInfo) ->
+    {Start, End} = case {Int =< MinInt+100, Int >= MaxInt-100} of
+		       {true, false} ->
+			   {MinInt, MinInt+100};
+		       {false, false} ->
+			   {smaller_valid_uniqint(Int-100, UinqintInfo),
+			    valid_uniqint(Int+100, UinqintInfo)};
+		       {false, true} ->
+			   {MaxInt-100, MaxInt}
+		   end,
+    lists:foldl(fun (I, OldRefInt) ->
+			RefInt = valid_uniqint(I, UinqintInfo),
+			case OldRefInt =:= RefInt of
+			    true ->
+				ok;
+			    false ->
+				check_uniqint(RefInt, UinqintInfo)
+			end,
+			RefInt
+		end,
+		none,
+		lists:seq(Start, End)).
+
+
+%% helpers
+
+print_ret_val(File, Line, Value) ->    
+    io:format("~s:~p: ~p~n", [File, Line, Value]),
+    Value.
+
+start_node(Config) ->
+    start_node(Config, []).
+start_node(Config, Opts) when is_list(Config), is_list(Opts) ->
+    ?line Pa = filename:dirname(code:which(?MODULE)),
+    ?line A = erlang:monotonic_time(1) + erlang:time_offset(1),
+    ?line B = erlang:unique_integer([positive]),
+    ?line Name = list_to_atom(atom_to_list(?MODULE)
+			      ++ "-"
+			      ++ atom_to_list(?config(testcase, Config))
+			      ++ "-"
+			      ++ integer_to_list(A)
+			      ++ "-"
+			      ++ integer_to_list(B)),
+    ?line ?t:start_node(Name, slave, [{args, Opts++" -pa "++Pa}]).
+
+stop_node(Node) ->
+    ?t:stop_node(Node).
diff --git a/erts/etc/common/erlexec.c b/erts/etc/common/erlexec.c
index 5ebde8ca3c..d33ea59c1d 100644
--- a/erts/etc/common/erlexec.c
+++ b/erts/etc/common/erlexec.c
@@ -807,6 +807,7 @@ int main(int argc, char **argv)
 		  case 'a':
 		  case 'A':
 		  case 'b':
+		  case 'C':
 		  case 'e':
 		  case 'i':
 		  case 'n':
@@ -880,6 +881,19 @@ int main(int argc, char **argv)
 		      }
 		      add_Eargs(argv[i]);
 		      break;
+		  case 'c':
+		      argv[i][0] = '-';
+		      if (argv[i][2] == '\0' && i+1 < argc) {
+			  if (sys_strcmp(argv[i+1], "true") == 0
+			      || sys_strcmp(argv[i+1], "false") == 0) {
+			      add_Eargs(argv[i]);
+			      add_Eargs(argv[i+1]);
+			      i++;
+			      break;
+			  }
+		      }
+		      add_Eargs(argv[i]);
+		      break;
 		  case 'M': {
 		      int x;
 		      for (x = 0; plusM_au_allocs[x]; x++)
@@ -1149,8 +1163,8 @@ usage_aux(void)
 #endif
 	  "] "
 	  "[-make] [-man [manopts] MANPAGE] [-x] [-emu_args] "
-	  "[-args_file FILENAME] [+A THREADS] [+a SIZE] [+B[c|d|i]] [+c] "
-	  "[+h HEAP_SIZE_OPTION] [+K BOOLEAN] "
+	  "[-args_file FILENAME] [+A THREADS] [+a SIZE] [+B[c|d|i]] [+c [BOOLEAN]] "
+	  "[+C MODE] [+h HEAP_SIZE_OPTION] [+K BOOLEAN] "
 	  "[+l] [+M<SUBSWITCH> <ARGUMENT>] [+P MAX_PROCS] [+Q MAX_PORTS] "
 	  "[+R COMPAT_REL] "
 	  "[+r] [+rg READER_GROUPS_LIMIT] [+s SCHEDULER_OPTION] "
diff --git a/erts/etc/common/heart.c b/erts/etc/common/heart.c
index 2830641802..a4f34e21d0 100644
--- a/erts/etc/common/heart.c
+++ b/erts/etc/common/heart.c
@@ -109,7 +109,7 @@
 #  include <sys/time.h>
 #  include <unistd.h>
 #  include <signal.h>
-#  if defined(CORRECT_USING_TIMES)
+#  if defined(OS_MONOTONIC_TIME_USING_TIMES)
 #    include <sys/times.h>
 #    include <limits.h>
 #  endif
@@ -1084,9 +1084,9 @@ time_t timestamp(time_t *res)
     return r;
 }
 
-#elif defined(HAVE_GETHRTIME)  || defined(GETHRTIME_WITH_CLOCK_GETTIME)
+#elif defined(OS_MONOTONIC_TIME_USING_GETHRTIME) || defined(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME)
 
-#if defined(GETHRTIME_WITH_CLOCK_GETTIME)
+#if defined(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME)
 typedef long long SysHrTime;
 
 SysHrTime sys_gethrtime(void);
@@ -1095,7 +1095,7 @@ SysHrTime sys_gethrtime(void)
 {
     struct timespec ts;
     long long result;
-    if (clock_gettime(CLOCK_MONOTONIC,&ts) != 0) {
+    if (clock_gettime(MONOTONIC_CLOCK_ID,&ts) != 0) {
 	print_error("Fatal, could not get clock_monotonic value, terminating! "
 		    "errno = %d\n", errno);
 	exit(1);
@@ -1122,7 +1122,7 @@ time_t timestamp(time_t *res)
     return r;
 }
 
-#elif defined(CORRECT_USING_TIMES)
+#elif defined(OS_MONOTONIC_TIME_USING_TIMES)
 
 #  ifdef NO_SYSCONF
 #    include <sys/param.h>
diff --git a/erts/etc/unix/cerl.src b/erts/etc/unix/cerl.src
index 78fefbea55..6f54475e5a 100644
--- a/erts/etc/unix/cerl.src
+++ b/erts/etc/unix/cerl.src
@@ -375,7 +375,9 @@ elif [ "x$GDB" = "xegdb" ]; then
         # Set annotation level for gdb in emacs 22 and higher. Seems to
         # be working with level 1 for emacs 22 and level 3 for emacs 23...
 	emacs_major=`$EMACS --version | head -1 | sed 's,^[^0-9]*\([0-9]*\).*,\1,g'`
-	if [ '!' -z "$emacs_major" -a $emacs_major -gt 22 ]; then
+	if [ '!' -z "$emacs_major" -a $emacs_major -gt 23 ]; then
+	    GDBARGS="-i=mi "
+	elif [ '!' -z "$emacs_major" -a $emacs_major -gt 22 ]; then
 	    GDBARGS="--annotate=3 "
 	elif [ '!' -z "$emacs_major" -a $emacs_major -gt 21 ]; then
 	    GDBARGS="--annotate=1 "
diff --git a/erts/example/Makefile b/erts/example/Makefile
index 6e1a88b4da..b637bee033 100644
--- a/erts/example/Makefile
+++ b/erts/example/Makefile
@@ -30,7 +30,7 @@ CFLAGS += $(OUR_C_FLAGS)
 CXXFLAGS += $(OUR_C_FLAGS)
 
 TARGETS = pg_sync.beam pg_async.beam pg_sync.so pg_async.so \
-next_perm.so next_perm.beam
+next_perm.so next_perm.beam time_compat.beam
 
 all: $(TARGETS)
 
diff --git a/erts/example/time_compat.erl b/erts/example/time_compat.erl
new file mode 100644
index 0000000000..d582117ceb
--- /dev/null
+++ b/erts/example/time_compat.erl
@@ -0,0 +1,302 @@
+%%
+%% %CopyrightBegin%
+%% 
+%% Copyright Ericsson AB 2014. All Rights Reserved.
+%% 
+%% The contents of this file are subject to the Erlang Public License,
+%% Version 1.1, (the "License"); you may not use this file except in
+%% compliance with the License. You should have received a copy of the
+%% Erlang Public License along with this software. If not, it can be
+%% retrieved online at http://www.erlang.org/.
+%% 
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and limitations
+%% under the License.
+%% 
+%% %CopyrightEnd%
+%%
+
+%%
+%% If your code need to be able to execute on ERTS versions both
+%% earlier and later than 7.0, the best approach is to use the new
+%% time API introduced in ERTS 7.0 and implement a fallback
+%% solution using the old primitives to be used on old ERTS
+%% versions. This way your code can automatically take advantage
+%% of the improvements in the API when available. This is an
+%% example of how to implement such an API, but it can be used
+%% as is if you want to. Just add this module to your project,
+%% and call the API via this module instead of calling the
+%% BIFs directly.
+%%
+
+-module(time_compat).
+
+%% We don't want warnings about the use of erlang:now/0 in
+%% this module.
+-compile(nowarn_deprecated_function).
+%%
+%% We don't use
+%%   -compile({nowarn_deprecated_function, [{erlang, now, 0}]}).
+%% since this will produce warnings when compiled on systems
+%% where it has not yet been deprecated.
+%%
+
+-export([monotonic_time/0,
+	 monotonic_time/1,
+	 erlang_system_time/0,
+	 erlang_system_time/1,
+	 os_system_time/0,
+	 os_system_time/1,
+	 time_offset/0,
+	 time_offset/1,
+	 convert_time_unit/3,
+	 timestamp/0,
+	 unique_integer/0,
+	 unique_integer/1,
+	 monitor/2,
+	 system_info/1,
+	 system_flag/2]).
+
+monotonic_time() ->
+    try
+	erlang:monotonic_time()
+    catch
+	error:undef ->
+	    %% Use Erlang system time as monotonic time
+	    erlang_system_time_fallback()
+    end.
+
+monotonic_time(Unit) ->
+    try
+	erlang:monotonic_time(Unit)
+    catch
+	error:badarg ->
+	    erlang:error(badarg, [Unit]);
+	error:undef ->
+	    %% Use Erlang system time as monotonic time
+	    STime = erlang_system_time_fallback(),
+	    try
+		convert_time_unit_fallback(STime, native, Unit)
+	    catch
+		error:bad_time_unit -> erlang:error(badarg, [Unit])
+	    end
+    end.
+
+erlang_system_time() ->
+    try
+	erlang:system_time()
+    catch
+	error:undef ->
+	    erlang_system_time_fallback()
+    end.
+
+erlang_system_time(Unit) ->
+    try
+	erlang:system_time(Unit)
+    catch
+	error:badarg ->
+	    erlang:error(badarg, [Unit]);
+	error:undef ->
+	    STime = erlang_system_time_fallback(),
+	    try
+		convert_time_unit_fallback(STime, native, Unit)
+	    catch
+		error:bad_time_unit -> erlang:error(badarg, [Unit])
+	    end
+    end.
+
+os_system_time() ->
+    try
+	os:system_time()
+    catch
+	error:undef ->
+	    os_system_time_fallback()
+    end.
+
+os_system_time(Unit) ->
+    try
+	os:system_time(Unit)
+    catch
+	error:badarg ->
+	    erlang:error(badarg, [Unit]);
+	error:undef ->
+	    STime = os_system_time_fallback(),
+	    try
+		convert_time_unit_fallback(STime, native, Unit)
+	    catch
+		error:bad_time_unit -> erlang:error(badarg, [Unit])
+	    end
+    end.
+
+time_offset() ->
+    try
+	erlang:time_offset()
+    catch
+	error:undef ->
+	    %% Erlang system time and Erlang monotonic
+	    %% time are always aligned
+	    0
+    end.
+
+time_offset(Unit) ->
+    try
+	erlang:time_offset(Unit)
+    catch
+	error:badarg ->
+	    erlang:error(badarg, [Unit]);
+	error:undef ->
+	    try
+		_ = integer_time_unit(Unit)
+	    catch
+		error:bad_time_unit -> erlang:error(badarg, [Unit])
+	    end,
+	    %% Erlang system time and Erlang monotonic
+	    %% time are always aligned
+	    0
+    end.
+
+convert_time_unit(Time, FromUnit, ToUnit) ->
+    try
+	erlang:convert_time_unit(Time, FromUnit, ToUnit)
+    catch
+	error:undef ->
+	    try
+		convert_time_unit_fallback(Time, FromUnit, ToUnit)
+	    catch
+		_:_ ->
+		    erlang:error(badarg, [Time, FromUnit, ToUnit])
+	    end;
+	error:Error ->
+	    erlang:error(Error, [Time, FromUnit, ToUnit])
+    end.
+
+timestamp() ->
+    try
+	erlang:timestamp()
+    catch
+	error:undef ->
+	    erlang:now()
+    end.
+
+unique_integer() ->
+    try
+	erlang:unique_integer()
+    catch
+	error:undef ->
+	    {MS, S, US} = erlang:now(),
+	    (MS*1000000+S)*1000000+US
+    end.
+
+unique_integer(Modifiers) ->
+    try
+	erlang:unique_integer(Modifiers)
+    catch
+	error:badarg ->
+	    erlang:error(badarg, [Modifiers]);
+	error:undef ->
+	    case is_valid_modifier_list(Modifiers) of
+		true ->
+		    %% now() converted to an integer
+		    %% fullfill the requirements of
+		    %% all modifiers: unique, positive,
+		    %% and monotonic...
+		    {MS, S, US} = erlang:now(),
+		    (MS*1000000+S)*1000000+US;
+		false ->
+		    erlang:error(badarg, [Modifiers])
+	    end
+    end.
+
+monitor(Type, Item) ->
+    try
+	erlang:monitor(Type, Item)
+    catch
+	error:Error ->
+	    case {Error, Type, Item} of
+		{badarg, time_offset, clock_service} ->
+		    %% Time offset is final and will never change.
+		    %% Return a dummy reference, there will never
+		    %% be any need for 'CHANGE' messages...
+		    make_ref();
+		_ ->
+		    erlang:error(Error, [Type, Item])
+	    end
+    end.
+
+system_info(Item) ->
+    try
+	erlang:system_info(Item)
+    catch
+	error:badarg ->
+	    case Item of
+		time_correction ->
+		    case erlang:system_info(tolerant_timeofday) of
+			enabled -> true;
+			disabled -> false
+		    end;
+		time_warp_mode ->
+		    no_time_warp;
+		time_offset ->
+		    final;
+		NotSupArg when NotSupArg == os_monotonic_time_source;
+			       NotSupArg == start_time ->
+		    %% Cannot emulate this...
+		    erlang:error(notsup, [NotSupArg]);
+		_ ->
+		    erlang:error(badarg, [Item])
+	    end;
+	error:Error ->
+	    erlang:error(Error, [Item])
+    end.
+
+system_flag(Flag, Value) ->
+    try
+	erlang:system_flag(Flag, Value)
+    catch
+	error:Error ->
+	    case {Error, Flag, Value} of
+		{badarg, time_offset, finalize} ->
+		    %% Time offset is final
+		    final;
+		_ ->
+		    erlang:error(Error, [Flag, Value])
+	    end
+    end.
+
+%%
+%% Internal functions
+%%
+
+integer_time_unit(native) -> 1000*1000;
+integer_time_unit(nano_seconds) -> 1000*1000*1000;
+integer_time_unit(micro_seconds) -> 1000*1000;
+integer_time_unit(milli_seconds) -> 1000;
+integer_time_unit(seconds) -> 1;
+integer_time_unit(I) when is_integer(I), I > 0 -> I;
+integer_time_unit(BadRes) -> erlang:error(bad_time_unit, [BadRes]).
+
+erlang_system_time_fallback() ->
+    {MS, S, US} = erlang:now(),
+    (MS*1000000+S)*1000000+US.
+
+os_system_time_fallback() ->
+    {MS, S, US} = os:timestamp(),
+    (MS*1000000+S)*1000000+US.
+
+convert_time_unit_fallback(Time, FromUnit, ToUnit) ->
+    FU = integer_time_unit(FromUnit),
+    TU = integer_time_unit(ToUnit),
+    case Time < 0 of
+	true -> TU*Time - (FU - 1);
+	false -> TU*Time
+    end div FU.
+
+is_valid_modifier_list([positive|Ms]) ->
+    is_valid_modifier_list(Ms);
+is_valid_modifier_list([monotonic|Ms]) ->
+    is_valid_modifier_list(Ms);
+is_valid_modifier_list([]) ->
+    true;
+is_valid_modifier_list(_) ->
+    false.
diff --git a/erts/include/internal/ethread_header_config.h.in b/erts/include/internal/ethread_header_config.h.in
index b36322490a..ffd9d350e2 100644
--- a/erts/include/internal/ethread_header_config.h.in
+++ b/erts/include/internal/ethread_header_config.h.in
@@ -237,3 +237,18 @@
 
 /* Assumed cache-line size (in bytes) */
 #undef ASSUMED_CACHE_LINE_SIZE
+
+/* Define if you have a clock_gettime() with a monotonic clock */
+#undef ETHR_HAVE_CLOCK_GETTIME_MONOTONIC
+
+/* Define if you have a monotonic gethrtime() */
+#undef ETHR_HAVE_GETHRTIME
+
+/* Define if you have a mach clock_get_time() with a monotonic clock */
+#undef ETHR_HAVE_MACH_CLOCK_GET_TIME
+
+/* Define to the monotonic clock id to use */
+#undef ETHR_MONOTONIC_CLOCK_ID
+
+
+
diff --git a/erts/preloaded/ebin/erlang.beam b/erts/preloaded/ebin/erlang.beam
index 7a3d94dd16..4ec388a7b9 100644
--- a/erts/preloaded/ebin/erlang.beam
+++ b/erts/preloaded/ebin/erlang.beam
diff --git a/erts/preloaded/ebin/erts_internal.beam b/erts/preloaded/ebin/erts_internal.beam
index 9b364d8b21..705bb61247 100644
--- a/erts/preloaded/ebin/erts_internal.beam
+++ b/erts/preloaded/ebin/erts_internal.beam
diff --git a/erts/preloaded/ebin/init.beam b/erts/preloaded/ebin/init.beam
index a190129b2c..aadc9797cb 100644
--- a/erts/preloaded/ebin/init.beam
+++ b/erts/preloaded/ebin/init.beam
diff --git a/erts/preloaded/src/erlang.erl b/erts/preloaded/src/erlang.erl
index 611a568014..79eb60f362 100644
--- a/erts/preloaded/src/erlang.erl
+++ b/erts/preloaded/src/erlang.erl
@@ -38,7 +38,6 @@
 
 -export([integer_to_list/2]).
 -export([integer_to_binary/2]).
--export([flush_monitor_message/2]).
 -export([set_cpu_topology/1, format_cpu_topology/1]).
 -export([await_proc_exit/3]).
 -export([memory/0, memory/1]).
@@ -48,7 +47,7 @@
 	 await_sched_wall_time_modifications/2,
 	 gather_gc_info_result/1]).
 
--deprecated([hash/2]).
+-deprecated([hash/2, now/0]).
 
 %% Get rid of autoimports of spawn to avoid clashes with ourselves.
 -compile({no_auto_import,[spawn_link/1]}).
@@ -58,12 +57,21 @@
 -compile({no_auto_import,[spawn_opt/5]}).
 
 -export_type([timestamp/0]).
+-export_type([time_unit/0]).
 
 -type ext_binary() :: binary().
 -type timestamp() :: {MegaSecs :: non_neg_integer(),
                       Secs :: non_neg_integer(),
                       MicroSecs :: non_neg_integer()}.
 
+-type time_unit() ::
+	pos_integer()
+      | 'seconds'
+      | 'milli_seconds'
+      | 'micro_seconds'
+      | 'nano_seconds'
+      | 'native'.
+
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %% Native code BIF stubs and their types
 %% (BIF's actually implemented in this module goes last in the file)
@@ -104,7 +112,8 @@
 -export([list_to_bitstring/1, list_to_existing_atom/1, list_to_float/1]).
 -export([list_to_integer/1, list_to_integer/2]).
 -export([list_to_pid/1, list_to_tuple/1, loaded/0]).
--export([localtime/0, make_ref/0, map_size/1, match_spec_test/3, md5/1, md5_final/1]).
+-export([localtime/0, make_ref/0]).
+-export([map_size/1, match_spec_test/3, md5/1, md5_final/1]).
 -export([md5_init/0, md5_update/2, module_loaded/1, monitor/2]).
 -export([monitor_node/2, monitor_node/3, nif_error/1, nif_error/2]).
 -export([node/0, node/1, now/0, phash/2, phash2/1, phash2/2]).
@@ -112,6 +121,11 @@
 -export([port_connect/2, port_control/3, port_get_data/1]).
 -export([port_set_data/2, port_to_list/1, ports/0]).
 -export([posixtime_to_universaltime/1, pre_loaded/0, prepare_loading/2]).
+-export([monotonic_time/0, monotonic_time/1]).
+-export([system_time/0, system_time/1]).
+-export([convert_time_unit/3]).
+-export([unique_integer/0, unique_integer/1]).
+-export([time_offset/0, time_offset/1, timestamp/0]).
 -export([process_display/2]).
 -export([process_flag/3, process_info/1, processes/0, purge_module/1]).
 -export([put/2, raise/3, read_timer/1, ref_to_list/1, register/2]).
@@ -1184,13 +1198,18 @@ md5_update(_Context, _Data) ->
 module_loaded(_Module) ->
     erlang:nif_error(undefined).
 
+-type registered_name() :: atom().
+
+-type registered_process_identifier() :: registered_name() | {registered_name(), node()}.
+
+-type monitor_process_identifier() :: pid() | registered_process_identifier().
+
 %% monitor/2
--spec monitor(Type, Item) -> MonitorRef when
-      Type :: process,
-      Item :: pid() | RegName | {RegName, Node},
-      RegName :: module(),
-      Node :: node(),
+-spec monitor(process, monitor_process_identifier()) -> MonitorRef when
+      MonitorRef :: reference();
+	     (time_offset, clock_service) -> MonitorRef when
       MonitorRef :: reference().
+
 monitor(_Type, _Item) ->
     erlang:nif_error(undefined).
 
@@ -1292,6 +1311,90 @@ ports() ->
 posixtime_to_universaltime(_P1) ->
     erlang:nif_error(undefined).
 
+-spec erlang:unique_integer(ModifierList) -> integer() when
+      ModifierList :: [Modifier],
+      Modifier :: positive | monotonic.
+
+unique_integer(_ModifierList) ->
+    erlang:nif_error(undefined).
+
+-spec erlang:unique_integer() -> integer().
+
+unique_integer() ->
+    erlang:nif_error(undefined).
+
+-spec erlang:monotonic_time() -> integer().
+
+monotonic_time() ->
+    erlang:nif_error(undefined).
+
+-spec erlang:monotonic_time(Unit) -> integer() when
+      Unit :: time_unit().
+
+monotonic_time(_Unit) ->
+    erlang:nif_error(undefined).
+
+-spec erlang:system_time() -> integer().
+
+system_time() ->
+    erlang:nif_error(undefined).
+
+-spec erlang:system_time(Unit) -> integer() when
+      Unit :: time_unit().
+
+system_time(_Unit) ->
+    erlang:nif_error(undefined).
+
+-spec erlang:convert_time_unit(Time, FromUnit, ToUnit) -> ConvertedTime when
+      Time :: integer(),
+      ConvertedTime :: integer(),
+      FromUnit :: time_unit(),
+      ToUnit :: time_unit().
+
+convert_time_unit(Time, FromUnit, ToUnit) ->
+    try
+	FU = case FromUnit of
+		 native -> erts_internal:time_unit();
+		 nano_seconds -> 1000*1000*1000;
+		 micro_seconds -> 1000*1000;
+		 milli_seconds -> 1000;
+		 seconds -> 1;
+		 _ when FromUnit > 0 -> FromUnit
+	     end,
+	TU = case ToUnit of
+		 native -> erts_internal:time_unit();
+		 nano_seconds -> 1000*1000*1000;
+		 micro_seconds -> 1000*1000;
+		 milli_seconds -> 1000;
+		 seconds -> 1;
+		 _ when ToUnit > 0 -> ToUnit
+	     end,
+	case Time < 0 of
+	    true -> TU*Time - (FU - 1);
+	    false -> TU*Time
+	end div FU
+    catch
+	_ : _ ->
+	    erlang:error(badarg, [Time, FromUnit, ToUnit])
+    end.
+
+-spec erlang:time_offset() -> integer().
+
+time_offset() ->
+    erlang:nif_error(undefined).
+
+-spec erlang:time_offset(Unit) -> integer() when
+      Unit :: time_unit().
+
+time_offset(_Unit) ->
+    erlang:nif_error(undefined).
+
+-spec erlang:timestamp() -> Timestamp when
+      Timestamp :: timestamp().
+
+timestamp() ->
+    erlang:nif_error(undefined).
+
 %% prepare_loading/2
 -spec erlang:prepare_loading(Module, Code) -> PreparedCode | {error, Reason} when
       Module :: module(),
@@ -2118,6 +2221,8 @@ subtract(_,_) ->
                         (trace_control_word, TCW) -> OldTCW when
       TCW :: non_neg_integer(),
       OldTCW :: non_neg_integer();
+			(time_offset, finalize) -> OldState when
+      OldState :: preliminary | final | volatile;
                         %% These are deliberately not documented
 			(internal_cpu_topology, term()) -> term();
                         (sequential_tracer, pid() | port() | false) -> pid() | port() | false;
@@ -2254,6 +2359,7 @@ tuple_to_list(_Tuple) ->
          (multi_scheduling_blockers) -> [PID :: pid()];
          (nif_version) -> string();
          (otp_release) -> string();
+         (os_monotonic_time_source) -> [{atom(),term()}];
          (port_count) -> non_neg_integer();
          (port_limit) -> pos_integer();
          (process_count) -> pos_integer();
@@ -2271,10 +2377,14 @@ tuple_to_list(_Tuple) ->
          (scheduler_id) -> SchedulerId :: pos_integer();
          (schedulers | schedulers_online) -> pos_integer();
          (smp_support) -> boolean();
+         (start_time) -> integer();
          (system_version) -> string();
          (system_architecture) -> string();
          (threads) -> boolean();
          (thread_pool_size) -> non_neg_integer();
+         (time_correction) -> true | false;
+         (time_offset) -> preliminary | final | volatile;
+         (time_warp_mode) -> no_time_warp | single_time_warp | multi_time_warp;
          (tolerant_timeofday) -> enabled | disabled;
          (trace_control_word) -> non_neg_integer();
          (update_cpu_info) -> changed | unchanged;
@@ -3041,16 +3151,6 @@ integer_to_binary(I0, Base, R0) ->
         true -> integer_to_binary(I1, Base, R1)
     end.
 
-%% erlang:flush_monitor_message/2 is for internal use only!
-%%
-%% erlang:demonitor(Ref, [flush]) traps to
-%% erlang:flush_monitor_message(Ref, Res) when
-%% it needs to flush a monitor message.
-flush_monitor_message(Ref, Res) when erlang:is_reference(Ref),
-                                     erlang:is_atom(Res) ->
-    receive {_, Ref, _, _, _} -> ok after 0 -> ok end,
-    Res.
-
 -record(cpu, {node = -1,
 	      processor = -1,
 	      processor_node = -1,
diff --git a/erts/preloaded/src/erts_internal.erl b/erts/preloaded/src/erts_internal.erl
index 2c5bd82cf0..30df75b406 100644
--- a/erts/preloaded/src/erts_internal.erl
+++ b/erts/preloaded/src/erts_internal.erl
@@ -38,6 +38,10 @@
 
 -export([check_process_code/2]).
 
+-export([flush_monitor_messages/3]).
+
+-export([time_unit/0]).
+
 %%
 %% Await result of send to port
 %%
@@ -178,3 +182,29 @@ cmp_term(_A,_B) ->
 
 map_to_tuple_keys(_M) ->
     erlang:nif_error(undefined).
+
+-spec erts_internal:flush_monitor_messages(Ref, Multi, Res) -> term() when
+      Ref :: reference(),
+      Multi :: boolean(),
+      Res :: term().
+
+%% erlang:demonitor(Ref, [flush]) traps to
+%% erts_internal:flush_monitor_messages(Ref, Res) when
+%% it needs to flush monitor messages.
+flush_monitor_messages(Ref, Multi, Res) when is_reference(Ref) ->
+    receive
+	{_, Ref, _, _, _} ->
+	    case Multi of
+		false ->
+		    Res;
+		_ ->
+		    flush_monitor_messages(Ref, Multi, Res)
+	    end
+    after 0 ->
+	    Res
+    end.
+
+-spec erts_internal:time_unit() -> pos_integer().
+
+time_unit() ->
+    erlang:nif_error(undefined).
diff --git a/erts/vsn.mk b/erts/vsn.mk
index d0dc8f7243..ab98bd4a17 100644
--- a/erts/vsn.mk
+++ b/erts/vsn.mk
@@ -17,7 +17,7 @@
 # %CopyrightEnd%
 # 
 
-VSN = 6.3
+VSN = 7.0
 
 # Port number 4365 in 4.2
 # Port number 4366 in 4.3
diff --git a/lib/kernel/doc/src/os.xml b/lib/kernel/doc/src/os.xml
index 2b57e75023..763bf01cc9 100644
--- a/lib/kernel/doc/src/os.xml
+++ b/lib/kernel/doc/src/os.xml
@@ -129,14 +129,49 @@ DirOut = os:cmd("dir"), % on Win32 platform</code>
       </desc>
     </func>
     <func>
+      <name name="system_time" arity="0"/>
+      <fsummary>Current OS system time</fsummary>
+      <desc>
+	<p>Returns current
+	<seealso marker="erts:time_correction#OS_System_Time">OS system time</seealso>
+	in <c>native</c>
+	<seealso marker="erts:erlang#type_time_unit">time unit</seealso>.</p>
+
+	<note><p>This time is <em>not</em> a monotonically increasing time.</p></note>
+      </desc>
+    </func>
+    <func>
+      <name name="system_time" arity="1"/>
+      <fsummary>Current OS system time</fsummary>
+      <desc>
+	<p>Returns current
+	<seealso marker="erts:time_correction#OS_System_Time">OS system time</seealso>
+	converted into the <c><anno>Unit</anno></c> passed as argument.</p>
+
+	<p>Calling <c>os:system_time(<anno>Unit</anno>)</c> is equivalent to: 
+	<seealso marker="erts:erlang#convert_time_unit/3"><c>erlang:convert_time_unit</c></seealso><c>(</c><seealso marker="#system_time/0"><c>os:system_time()</c></seealso><c>,
+	native, <anno>Unit</anno>)</c>.</p>
+
+	<note><p>This time is <em>not</em> a monotonically increasing time.</p></note>
+      </desc>
+    </func>
+    <func>
       <name name="timestamp" arity="0"/>
       <type_desc variable="Timestamp">Timestamp = {MegaSecs, Secs, MicroSecs}</type_desc>
-      <fsummary>Returna a timestamp from the OS in the erlang:now/0 format</fsummary>
+      <fsummary>Current OS system time on the erlang:timestamp/0 format</fsummary>
       <desc>
-      <p>Returns a tuple in the same format as <seealso marker="erts:erlang#now/0">erlang:now/0</seealso>. The difference is that this function returns what the operating system thinks (a.k.a. the wall clock time) without any attempts at time correction. The result of two different calls to this function is <em>not</em> guaranteed to be different.</p>
-      <p>The most obvious use for this function is logging. The tuple can be used together with the function <seealso marker="stdlib:calendar#now_to_universal_time/1">calendar:now_to_universal_time/1</seealso> 
-or <seealso marker="stdlib:calendar#now_to_local_time/1">calendar:now_to_local_time/1</seealso> to get calendar time. Using the calendar time together with the <c>MicroSecs</c> part of the return tuple from this function allows you to log timestamps in high resolution and consistent with the time in the rest of the operating system.</p>
-      <p>Example of code formatting a string in the format &quot;DD Mon YYYY HH:MM:SS.mmmmmm&quot;, where DD is the day of month, Mon is the textual month name, YYYY is the year, HH:MM:SS is the time and mmmmmm is the microseconds in six positions:</p>
+      <p>Returns current
+	<seealso marker="erts:time_correction#OS_System_Time">OS system time</seealso>
+        in the same format as <seealso marker="erts:erlang#timestamp/0">erlang:timestamp/0</seealso>.
+	The tuple can be used together with the function
+	<seealso marker="stdlib:calendar#now_to_universal_time/1">calendar:now_to_universal_time/1</seealso> 
+        or <seealso marker="stdlib:calendar#now_to_local_time/1">calendar:now_to_local_time/1</seealso> to
+        get calendar time. Using the calendar time together with the <c>MicroSecs</c> part of the return
+        tuple from this function allows you to log timestamps in high resolution and consistent with the
+        time in the rest of the operating system.</p>
+      <p>Example of code formatting a string in the format &quot;DD Mon YYYY HH:MM:SS.mmmmmm&quot;, where
+         DD is the day of month, Mon is the textual month name, YYYY is the year, HH:MM:SS is the time and
+         mmmmmm is the microseconds in six positions:</p>
 <code>
 -module(print_time).
 -export([format_utc_timestamp/0]).
@@ -155,6 +190,9 @@ format_utc_timestamp() ->
 1> <input>io:format("~s~n",[print_time:format_utc_timestamp()]).</input>
 29 Apr 2009  9:55:30.051711
 </pre>
+       <p>OS system time can also be retreived by
+	<c><seealso marker="#system_time/0"><c>os:system_time/0</c></seealso></c>,
+	and <seealso marker="#system_time/1"><c>os:system_time/1</c></seealso>.</p>
       </desc>
     </func>
     <func>
diff --git a/lib/kernel/src/os.erl b/lib/kernel/src/os.erl
index 187fd0001b..3d308a43b0 100644
--- a/lib/kernel/src/os.erl
+++ b/lib/kernel/src/os.erl
@@ -26,7 +26,8 @@
 
 %%% BIFs
 
--export([getenv/0, getenv/1, getpid/0, putenv/2, timestamp/0, unsetenv/1]).
+-export([getenv/0, getenv/1, getpid/0, putenv/2, system_time/0, system_time/1,
+	 timestamp/0, unsetenv/1]).
 
 -spec getenv() -> [string()].
 
@@ -52,6 +53,17 @@ getpid() ->
 putenv(_, _) ->
     erlang:nif_error(undef).
 
+-spec system_time() -> integer().
+
+system_time() ->
+    erlang:nif_error(undef).
+
+-spec system_time(Unit) -> integer() when
+      Unit :: erlang:time_unit().
+
+system_time(_Unit) ->
+    erlang:nif_error(undef).
+
 -spec timestamp() -> Timestamp when
       Timestamp :: erlang:timestamp().
 
diff --git a/lib/stdlib/src/otp_internal.erl b/lib/stdlib/src/otp_internal.erl
index 6c25beabe9..0c59af621d 100644
--- a/lib/stdlib/src/otp_internal.erl
+++ b/lib/stdlib/src/otp_internal.erl
@@ -59,6 +59,11 @@ obsolete_1(erl_eval, arg_list, 3) ->
 obsolete_1(erlang, hash, 2) ->
     {deprecated, {erlang, phash2, 2}};
 
+obsolete_1(erlang, now, 0) ->
+    {deprecated,
+     "Deprecated BIF. See the \"Time and Time Correction in Erlang\" "
+     "chapter of the ERTS User's Guide for more information."};
+
 obsolete_1(calendar, local_time_to_universal_time, 1) ->
     {deprecated, {calendar, local_time_to_universal_time_dst, 1}};
 
diff --git a/system/doc/efficiency_guide/advanced.xml b/system/doc/efficiency_guide/advanced.xml
index 51f1b2612c..ed7a6670ed 100644
--- a/system/doc/efficiency_guide/advanced.xml
+++ b/system/doc/efficiency_guide/advanced.xml
@@ -199,6 +199,31 @@ On 64-bit architectures: 4 words for a reference from the current local node, an
        available, and operating system specific settings and limits.</item>
       <tag><em>Number of arguments to a function or fun</em></tag>
       <item>255</item>
+      <tag><marker id="unique_references"/><em>Unique References on a Runtime System Instance</em></tag>
+      <item>Each scheduler thread has its own set of references, and all
+      other threads have a shared set of references. Each set of references
+      consist of <c>2⁶⁴ - 1</c> unique references. That is the total
+      amount of unique references that can be produced on a runtime
+      system instance is <c>(NoSchedulers + 1) * (2⁶⁴ - 1)</c>. If a
+      scheduler thread create a new reference each nano second,
+      references will at earliest be reused after more than 584 years.
+      That is, for the foreseeable future they are unique enough.</item>
+      <tag><marker id="unique_integers"/><em>Unique Integers on a Runtime System Instance</em></tag>
+      <item>There are two types of unique integers both created using the
+      <seealso marker="erts:erlang#unique_integer/1">erlang:unique_integer()</seealso>
+      BIF. Unique integers created:
+      <taglist>
+	<tag><em>with</em> the <c>monotonic</c> modifier</tag>
+	<item>consist of a set of <c>2⁶⁴ - 1</c> unique integers.</item>
+	<tag><em>without</em> the <c>monotonic</c> modifier</tag>
+	<item>consist of a set of <c>2⁶⁴ - 1</c> unique integers per scheduler
+	thread and a set of <c>2⁶⁴ - 1</c> unique integers shared by
+	other threads. That is the total amount of unique integers without
+	the <c>monotonic</c> modifier is <c>(NoSchedulers + 1) * (2⁶⁴ - 1)</c></item>
+      </taglist>
+      If a unique integer is created each nano second, unique integers
+      will at earliest be reused after more than 584 years. That is, for
+      the foreseeable future they are unique enough.</item>
     </taglist>
   </section>
 </chapter>