Merge branch 'rickard/timer-optimization/OTP-12650'

* rickard/timer-optimization/OTP-12650:
  Timer fixes, documentation, and test cases

Conflicts:
	erts/emulator/beam/erl_hl_timer.c

9 files changed, 657 insertions, 181 deletions

diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index ba5f80a9c1..6ca57566aa 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -536,29 +536,69 @@
       </desc>
     </func>
     <func>
-      <name name="cancel_timer" arity="1"/>
+      <name name="cancel_timer" arity="2"/>
       <fsummary>Cancel a timer</fsummary>
       <desc>
-        <p>Cancels a timer, where <c><anno>TimerRef</anno></c> was returned by
-          either
-          <seealso marker="#send_after/3">erlang:send_after/3</seealso>
-          or
-          <seealso marker="#start_timer/3">erlang:start_timer/3</seealso>.
-          If the timer is there to be removed, the function returns
-          the time in milliseconds left until the timer would have expired,
-          otherwise <c>false</c> (which means that <c><anno>TimerRef</anno></c> was
-          never a timer, that it has already been cancelled, or that it
-          has already delivered its message).</p>
+        <p>Cancels a timer. <c><anno>TimerRef</anno></c> needs to refer to
+	a timer	that was created by either
+	<seealso marker="#send_after/4"><c>erlang:send_after()</c></seealso>,
+        or <seealso marker="#start_timer/4"><c>erlang:start_timer()</c></seealso>.</p>
+	<p>Currently available <c><anno>Option</anno>s</c>:</p>
+        <taglist>
+          <tag><c>{async, Async}</c></tag>
+          <item>
+	    <p>Asynchronous request for cancellation. <c>Async</c>
+	    defaults to <c>false</c>. That is the operation will be
+	    performed synchronously. When <c>Async</c> is set to
+	    <c>true</c> the cancel operation will be performed
+	    asynchronously. That is, <c>cancel_timer()</c> will send
+	    a request for cancellation to the timer service that
+	  manages the timer, and then return <c>ok</c>.</p></item>
+          <tag><c>{info, Info}</c></tag>
+          <item>
+	    <p>Request information about the <c>Result</c> of the
+	    cancellation. <c>Info</c> defaults to <c>true</c>. That
+	    is information will be given. When <c>Info</c> is set to
+	    <c>false</c> no information about the result of the cancel
+	    operation will be given. When the operation is performed
+	    synchronously the <c>Result</c> will returned from
+	    <c>cancel_timer()</c>. When the operation is performed
+	    asynchronously, a message on the form
+	    <c>{cancel_timer, <anno>TimerRef</anno>, <anno>Result</anno>}</c>
+	    will be sent to the caller of <c>cancel_timer()</c> when
+	    the operation has been performed.</p></item>
+        </taglist>
+	<p>When the <c><anno>Result</anno></c> equals <c>false</c> a timer
+	corresponding to <c><anno>TimerRef</anno></c> could not be found. This
+	can be either because the timer had expired, been canceled, or because
+	<c><anno>TimerRef</anno></c> do not correspond to a timer. When the
+	<c><anno>Result</anno></c> is an integer, it represents
+	the time in milli seconds left before the timer will expire.</p>
+	<note><p>The timer service that manages the timer may be co-located
+	with another scheduler than the scheduler that the calling process
+	is executing on. In this case communication with the timer
+	service will be performed using asynchronous signals. If the calling
+	process is in critical path and can do other things while waiting
+	for the result of this operation, you want to use the <c>{async, true}</c>
+	option.</p></note>
         <p>See also 
-          <seealso marker="#send_after/3">erlang:send_after/3</seealso>,
-          <seealso marker="#start_timer/3">erlang:start_timer/3</seealso>,
+          <seealso marker="#send_after/4"><c>erlang:send_after/4</c></seealso>,
+          <seealso marker="#start_timer/4"><c>erlang:start_timer/4</c></seealso>,
           and
-          <seealso marker="#read_timer/1">erlang:read_timer/1</seealso>.</p>
+          <seealso marker="#read_timer/2"><c>erlang:read_timer/2</c></seealso>.</p>
         <p>Note: Cancelling a timer does not guarantee that the message
           has not already been delivered to the message queue.</p>
       </desc>
     </func>
-
+    <func>
+      <name name="cancel_timer" arity="1"/>
+      <fsummary>Cancel a timer</fsummary>
+      <desc>
+        <p>Cancels a timer. The same as calling
+	<seealso marker="#cancel_timer/2"><c>erlang:cancel_timer(TimerRef,
+	[{async, false}, {info, true}])</c></seealso>.</p>
+      </desc>
+    </func>
     <func>
       <name name="check_old_code" arity="1"/>
       <fsummary>Check if a module has old code</fsummary>
@@ -4505,23 +4545,54 @@ os_prompt% </pre>
       </desc>
     </func>
     <func>
-      <name name="read_timer" arity="1"/>
-      <fsummary>Number of milliseconds remaining for a timer</fsummary>
-      <desc>
-        <p><c><anno>TimerRef</anno></c> is a timer reference returned by
-          <seealso marker="#send_after/3">erlang:send_after/3</seealso>
-          or
-          <seealso marker="#start_timer/3">erlang:start_timer/3</seealso>.
-          If the timer is active, the function returns the time in
-          milliseconds left until the timer will expire, otherwise
-          <c>false</c> (which means that <c><anno>TimerRef</anno></c> was never a
-          timer, that it has been cancelled, or that it has already
-          delivered its message).</p>
+      <name name="read_timer" arity="2"/>
+      <fsummary>Read the state of a timer</fsummary>
+      <desc>
+        <p>Read the state of a timer. <c><anno>TimerRef</anno></c> 
+	needs to refer to a timer that was created by either
+	<seealso marker="#send_after/4"><c>erlang:send_after()</c></seealso>,
+        or <seealso marker="#start_timer/4"><c>erlang:start_timer()</c></seealso>.</p>
+	<p>Currently available <c><anno>Option</anno>s</c>:</p>
+        <taglist>
+          <tag><c>{async, Async}</c></tag>
+          <item>
+	    <p>Asynchronous request. <c>Async</c> defaults to <c>false</c>. That
+	    is the operation will be performed synchronously, and the <c>Result</c>
+	    will returned from <c>read_timer()</c>. When <c>Async</c> is set to
+	    <c>true</c>, <c>read_timer()</c> will send a request for the
+	    <c>Result</c> to a timer service that manages the timer and then
+	    return <c>ok</c>. A message  on the format
+	    <c>{read_timer, <anno>TimerRef</anno>, <anno>Result</anno>}</c>
+	    will be sent to the caller of <c>read_timer()</c> when
+	    the operation has been processed.</p></item>
+        </taglist>
+	<p>When the <c><anno>Result</anno></c> equals <c>false</c> a timer
+	corresponding to <c><anno>TimerRef</anno></c> could not be found. This
+	can be either because the timer had expired, been canceled, or because
+	<c><anno>TimerRef</anno></c> do not correspond to a timer. When the
+	<c><anno>Result</anno></c> is an integer, it represents
+	the time in milli seconds left before the timer will expire.</p>
+	<note><p>The timer service that manages the timer may be co-located
+	with another scheduler than the scheduler that the calling process
+	is executing on. In this case communication with the timer
+	service will be performed using asynchronous signals. If the calling
+	process is in critical path and can do other things while waiting
+	for the result of this operation, you want to use the <c>{async, true}</c>
+	option.</p></note>
         <p>See also 
-          <seealso marker="#send_after/3">erlang:send_after/3</seealso>,
-          <seealso marker="#start_timer/3">erlang:start_timer/3</seealso>,
+          <seealso marker="#send_after/4"><c>erlang:send_after/4</c></seealso>,
+          <seealso marker="#start_timer/4"><c>erlang:start_timer/4</c></seealso>,
           and
-          <seealso marker="#cancel_timer/1">erlang:cancel_timer/1</seealso>.</p>
+          <seealso marker="#cancel_timer/2"><c>erlang:cancel_timer/2</c></seealso>.</p>
+      </desc>
+    </func>
+    <func>
+      <name name="read_timer" arity="1"/>
+      <fsummary>Read the state of a timer</fsummary>
+      <desc>
+        <p>Read the state of a timer. The same as calling
+	<seealso marker="#read_timer/2"><c>erlang:read_timer(TimerRef,
+	[{async, false}])</c></seealso>.</p>
       </desc>
     </func>
     <func>
@@ -4670,6 +4741,63 @@ true</pre>
       </desc>
     </func>
     <func>
+      <name name="send_after" arity="4"/>
+      <fsummary>Start a timer</fsummary>
+      <desc>
+        <p>Starts a timer. When the timer expires, the message
+          <c><anno>Msg</anno></c> will be sent to
+	<c><anno>Dest</anno></c>.</p>
+	<p>If <c><anno>Dest</anno></c> is a <c>pid()</c> it has to
+	be a <c>pid()</c> of a local process, dead or alive.</p>
+	<p>Currently available <c><anno>Option</anno>s</c>:</p>
+        <taglist>
+          <tag><c>{abs, Abs}</c></tag>
+          <item>
+	    <p>Absolute timeout. When <c>Abs</c> is <c>false</c>
+	    the <c><anno>Time</anno></c> value will be interpreted
+	    as a time in milli-seconds relative current
+	    <seealso marker="time_correction#Erlang_Monotonic_Time">Erlang
+	    monotonic time</seealso>. When <c>Abs</c> is <c>true</c> the
+	    <c><anno>Time</anno></c> value will be interpreted as an absolute
+	    Erlang monotonic time of milli second time unit. <c>Abs</c>
+	    defaults to <c>false</c>.</p>
+	  </item>
+        </taglist>
+	<p>The absolute time when the timer is set to expire needs
+	to be in the range between
+	<seealso marker="#system_info_start_time"><c>erlang:system_info(start_time)</c></seealso>
+	and
+	<seealso marker="#system_info_end_time"><c>erlang:system_info(end_time)</c></seealso>.
+	If a negative relative time is specified the time is not
+	allowed to be negative.</p>
+        <p>If <c><anno>Dest</anno></c> is an <c>atom()</c>, it is supposed to be the name of
+          a registered process. The process referred to by the name is
+          looked up at the time of delivery. No error is given if
+          the name does not refer to a process.</p>
+        <p>If <c><anno>Dest</anno></c> is a <c>pid()</c>, the timer will be automatically
+          canceled if the process referred to by the <c>pid()</c> is not alive,
+          or when the process exits. This feature was introduced in
+          erts version 5.4.11. Note that timers will not be
+          automatically canceled when <c><anno>Dest</anno></c> is an <c>atom()</c>.</p>
+        <p>See also
+          <seealso marker="#start_timer/4"><c>erlang:send_timer/4</c></seealso>,
+          <seealso marker="#cancel_timer/2"><c>erlang:cancel_timer/2</c></seealso>,
+          and
+          <seealso marker="#read_timer/2"><c>erlang:read_timer/2</c></seealso>.</p>
+        <p>Failure: <c>badarg</c> if the arguments does not satisfy
+          the requirements specified above.</p>
+      </desc>
+    </func>
+    <func>
+      <name name="send_after" arity="3"/>
+      <fsummary>Start a timer</fsummary>
+      <desc>
+        <p>Starts a timer. The same as calling
+	<seealso marker="#send_timer/4"><c>erlang:send_after(<anno>Time</anno>,
+	<anno>Dest</anno>, <anno>Msg</anno>, [{abs, false}])</c></seealso>.</p>
+      </desc>
+    </func>
+    <func>
       <name name="send_after" arity="3"/>
       <type_desc variable="Time">0 &lt;= Time &lt;= 4294967295</type_desc>
       <fsummary>Start a timer</fsummary>
@@ -4690,9 +4818,9 @@ true</pre>
           automatically canceled when <c><anno>Dest</anno></c> is an <c>atom</c>.</p>
         <p>See also
           <seealso marker="#start_timer/3">erlang:start_timer/3</seealso>,
-          <seealso marker="#cancel_timer/1">erlang:cancel_timer/1</seealso>,
+          <seealso marker="#cancel_timer/2">erlang:cancel_timer/2</seealso>,
           and
-          <seealso marker="#read_timer/1">erlang:read_timer/1</seealso>.</p>
+          <seealso marker="#read_timer/2">erlang:read_timer/2</seealso>.</p>
         <p>Failure: <c>badarg</c> if the arguments does not satisfy
           the requirements specified above.</p>
       </desc>
@@ -5100,15 +5228,35 @@ true</pre>
       </desc>
     </func>
     <func>
-      <name name="start_timer" arity="3"/>
-      <type_desc variable="Time">0 &lt;= Time &lt;= 4294967295</type_desc>
+      <name name="start_timer" arity="4"/>
       <fsummary>Start a timer</fsummary>
       <desc>
-        <p>Starts a timer which will send the message
-          <c>{timeout, <anno>TimerRef</anno>, <anno>Msg</anno>}</c> to <c><anno>Dest</anno></c>
-          after <c><anno>Time</anno></c> milliseconds.</p>
-	<p>If <c><anno>Dest</anno></c> is a <c>pid()</c> it has to be a <c>pid()</c> of a local process, dead or alive.</p>
-	<p>The <c><anno>Time</anno></c> value can, in the current implementation, not be greater than 4294967295.</p>
+        <p>Starts a timer. When the timer expires, the message
+          <c>{timeout, <anno>TimerRef</anno>, <anno>Msg</anno>}</c>
+	  will be sent to <c><anno>Dest</anno></c>.</p>
+	<p>If <c><anno>Dest</anno></c> is a <c>pid()</c> it has to
+	be a <c>pid()</c> of a local process, dead or alive.</p>
+	<p>Currently available <c><anno>Option</anno>s</c>:</p>
+        <taglist>
+          <tag><c>{abs, Abs}</c></tag>
+          <item>
+	    <p>Absolute timeout. When <c>Abs</c> is <c>false</c>
+	    the <c><anno>Time</anno></c> value will be interpreted
+	    as a time in milli-seconds relative current
+	    <seealso marker="time_correction#Erlang_Monotonic_Time">Erlang
+	    monotonic time</seealso>. When <c>Abs</c> is <c>true</c> the
+	    <c><anno>Time</anno></c> value will be interpreted as an absolute
+	    Erlang monotonic time of milli second time unit. <c>Abs</c>
+	    defaults to <c>false</c>.</p>
+	  </item>
+        </taglist>
+	<p>The absolute time when the timer is set to expire needs
+	to be in the range between
+	<seealso marker="#system_info_start_time"><c>erlang:system_info(start_time)</c></seealso>
+	and
+	<seealso marker="#system_info_end_time"><c>erlang:system_info(end_time)</c></seealso>.
+	If a negative relative time is specified the time is not
+	allowed to be negative.</p>
         <p>If <c><anno>Dest</anno></c> is an <c>atom()</c>, it is supposed to be the name of
           a registered process. The process referred to by the name is
           looked up at the time of delivery. No error is given if
@@ -5119,15 +5267,24 @@ true</pre>
           erts version 5.4.11. Note that timers will not be
           automatically canceled when <c><anno>Dest</anno></c> is an <c>atom()</c>.</p>
         <p>See also
-          <seealso marker="#send_after/3">erlang:send_after/3</seealso>,
-          <seealso marker="#cancel_timer/1">erlang:cancel_timer/1</seealso>,
+          <seealso marker="#send_after/4"><c>erlang:send_after/4</c></seealso>,
+          <seealso marker="#cancel_timer/2"><c>erlang:cancel_timer/2</c></seealso>,
           and
-          <seealso marker="#read_timer/1">erlang:read_timer/1</seealso>.</p>
+          <seealso marker="#read_timer/2"><c>erlang:read_timer/2</c></seealso>.</p>
         <p>Failure: <c>badarg</c> if the arguments does not satisfy
           the requirements specified above.</p>
       </desc>
     </func>
     <func>
+      <name name="start_timer" arity="3"/>
+      <fsummary>Start a timer</fsummary>
+      <desc>
+        <p>Starts a timer. The same as calling
+	<seealso marker="#start_timer/4"><c>erlang:start_timer(<anno>Time</anno>,
+	<anno>Dest</anno>, <anno>Msg</anno>, [{abs, false}])</c></seealso>.</p>
+      </desc>
+    </func>
+    <func>
       <name name="statistics" arity="1" clause_i="1"/>
       <fsummary>Information about context switches</fsummary>
       <desc>
@@ -6236,6 +6393,14 @@ ok
             (i.e. <c>system_info(dynamic_trace)</c> returns
             <c>dtrace</c> or <c>systemtap</c>).</p>
           </item>
+	  <tag><marker id="system_info_end_time"/><c>end_time</c></tag>
+	  <item><p>The last <seealso marker="#monotonic_time/0">Erlang monotonic
+	  time</seealso> in <c>native</c>
+	  <seealso marker="#type_time_unit">time unit</seealso> that
+	  can be represented internally in the current Erlang runtime system
+	  instance. The time between the
+	  <seealso marker="#system_info_start_time">start time</seealso> and
+	  the end time is at least a quarter of a millennium.</p></item>
           <tag><c>elib_malloc</c></tag>
           <item>
             <p>This option will be removed in a future release.
diff --git a/erts/emulator/beam/erl_alloc.c b/erts/emulator/beam/erl_alloc.c
index b832626e7b..dcae5509ec 100644
--- a/erts/emulator/beam/erl_alloc.c
+++ b/erts/emulator/beam/erl_alloc.c
@@ -2331,6 +2331,22 @@ erts_memory(int *print_to_p, void *print_to_arg, void *proc, Eterm earg)
 		       &size.processes_used,
 		       fi,
 		       ERTS_ALC_T_MSG_REF);
+	add_fix_values(&size.processes,
+		       &size.processes_used,
+		       fi,
+		       ERTS_ALC_T_LL_PTIMER);
+	add_fix_values(&size.processes,
+		       &size.processes_used,
+		       fi,
+		       ERTS_ALC_T_HL_PTIMER);
+	add_fix_values(&size.processes,
+		       &size.processes_used,
+		       fi,
+		       ERTS_ALC_T_BIF_TIMER);
+	add_fix_values(&size.processes,
+		       &size.processes_used,
+		       fi,
+		       ERTS_ALC_T_ABIF_TIMER);
     }
 
     if (want.atom || want.atom_used) {
diff --git a/erts/emulator/beam/erl_hl_timer.c b/erts/emulator/beam/erl_hl_timer.c
index cf92ded415..51cd843935 100644
--- a/erts/emulator/beam/erl_hl_timer.c
+++ b/erts/emulator/beam/erl_hl_timer.c
@@ -850,8 +850,6 @@ hl_timer_destroy(ErtsHLTimer *tmr)
     if (!(roflgs & ERTS_TMR_ROFLG_BIF_TMR))
 	erts_free(ERTS_ALC_T_HL_PTIMER, tmr);
     else {
-	if (tmr->btm.bp)
-	    free_message_buffer(tmr->btm.bp);
 	if (roflgs & ERTS_TMR_ROFLG_PRE_ALC)
 	    bif_timer_pre_free(tmr);
 	else if (roflgs & ERTS_TMR_ROFLG_ABIF_TMR)
@@ -898,10 +896,6 @@ schedule_hl_timer_destroy(ErtsHLTimer *tmr, Uint32 roflgs)
 	 * Message buffer can be dropped at
 	 * once...
 	 */
-	if (tmr->btm.bp) {
-	    free_message_buffer(tmr->btm.bp);
-	    tmr->btm.bp = NULL;
-	}
 	size = sizeof(ErtsHLTimer);
     }
 
@@ -1121,6 +1115,7 @@ hlt_bif_timer_timeout(ErtsHLTimer *tmr, Uint32 roflgs)
 {
     ErtsProcLocks proc_locks = ERTS_PROC_LOCKS_MSG_SEND;
     Process *proc;
+    int queued_message = 0;
     int dec_refc = 0;
     Uint32 is_reg_name = (roflgs & ERTS_TMR_ROFLG_REG_NAME);
     ERTS_HLT_ASSERT(roflgs & ERTS_TMR_ROFLG_BIF_TMR);
@@ -1152,6 +1147,7 @@ hlt_bif_timer_timeout(ErtsHLTimer *tmr, Uint32 roflgs)
 	    erts_queue_message(proc, &proc_locks, tmr->btm.bp,
 			       tmr->btm.message, NIL);
 	    erts_smp_proc_unlock(proc, ERTS_PROC_LOCKS_MSG_SEND);
+	    queued_message = 1;
 	    proc_locks &= ~ERTS_PROC_LOCKS_MSG_SEND;
 	    tmr->btm.bp = NULL;
 	    if (tmr->btm.proc_tree.parent != ERTS_HLT_PFIELD_NOT_IN_TABLE) {
@@ -1165,6 +1161,8 @@ hlt_bif_timer_timeout(ErtsHLTimer *tmr, Uint32 roflgs)
 	if (dec_refc)
 	    hl_timer_pre_dec_refc(tmr);
     }
+    if (!queued_message && tmr->btm.bp)
+	free_message_buffer(tmr->btm.bp);
 }
 
 static ERTS_INLINE void
@@ -1682,6 +1680,8 @@ setup_bif_timer(Process *c_p, ErtsMonotonicTime timeout_pos,
 					  rcvr, ERTS_PROC_LOCK_BTM,
 					  ERTS_P2P_FLG_INC_REFC);
 	if (!proc) {
+	    if (tmr->btm.bp)
+		free_message_buffer(tmr->btm.bp);
 	    hlt_delete_timer(esdp, tmr);
 	    hl_timer_destroy(tmr);
 	}
@@ -1714,6 +1714,9 @@ cancel_bif_timer(ErtsHLTimer *tmr)
     if (state != ERTS_TMR_STATE_ACTIVE)
 	return 0;
 
+    if (tmr->btm.bp)
+	free_message_buffer(tmr->btm.bp);
+
     res = -1;
 
     roflgs = tmr->head.roflgs;
@@ -1827,18 +1830,25 @@ access_sched_local_btm(Process *c_p, Eterm pid,
 	if (!async)
 	    hsz += REF_THING_SIZE;
 	else {
-	    if (is_non_value(tref))
+	    if (is_non_value(tref) || proc != c_p)
 		hsz += REF_THING_SIZE;
 	    hsz += 1; /* upgrade to 3-tuple */
 	}
 	if (time_left > (Sint64) MAX_SMALL)
 	    hsz += ERTS_SINT64_HEAP_SIZE(time_left);
 
-	hp = erts_alloc_message_heap(hsz,
-				     &bp,
-				     &ohp,
-				     proc,
-				     &proc_locks);
+	if (proc == c_p) {
+	    bp = NULL;
+	    ohp = NULL;
+	    hp = HAlloc(c_p, hsz);
+	}
+	else {
+	    hp = erts_alloc_message_heap(hsz,
+					 &bp,
+					 &ohp,
+					 proc,
+					 &proc_locks);
+	}
 
 #ifdef ERTS_HLT_DEBUG
 	hp_end = hp + hsz;
@@ -1864,7 +1874,7 @@ access_sched_local_btm(Process *c_p, Eterm pid,
 	}
 	else {
 	    Eterm tag = cancel ? am_cancel_timer : am_read_timer;
-	    if (is_value(tref))
+	    if (is_value(tref) && proc == c_p)
 		ref = tref;
 	    else {
 		write_ref_thing(hp,
@@ -1975,8 +1985,6 @@ try_access_sched_remote_btm(ErtsSchedulerData *esdp,
     }
     else {
 	Eterm tag, res, msg;
-	ErlOffHeap *ohp;
-	ErlHeapFragment* bp;
 	Uint hsz;
 	Eterm *hp;
 	ErtsProcLocks proc_locks = ERTS_PROC_LOCK_MAIN;
@@ -1985,11 +1993,7 @@ try_access_sched_remote_btm(ErtsSchedulerData *esdp,
 	if (time_left > (Sint64) MAX_SMALL)
 	    hsz += ERTS_SINT64_HEAP_SIZE(time_left);
 
-	hp = erts_alloc_message_heap(hsz,
-				     &bp,
-				     &ohp,
-				     c_p,
-				     &proc_locks);
+	hp = HAlloc(c_p, hsz);
 	if (cancel)
 	    tag = am_cancel_timer;
 	else
@@ -2004,7 +2008,7 @@ try_access_sched_remote_btm(ErtsSchedulerData *esdp,
 
 	msg = TUPLE3(hp, tag, tref, res);
 
-	erts_queue_message(c_p, &proc_locks, bp, msg, NIL);
+	erts_queue_message(c_p, &proc_locks, NULL, msg, NIL);
 
 	proc_locks &= ~ERTS_PROC_LOCK_MAIN;
 	if (proc_locks)
@@ -2149,7 +2153,7 @@ parse_bif_timer_options(Eterm option_list, int *async, int *info,
     if (async)
 	*async = 0;
     if (info)
-	*info = 0;
+	*info = 1;
     if (abs)
 	*abs = 0;
     if (accessor)
@@ -2218,13 +2222,19 @@ exit_cancel_bif_timer(ErtsHLTimer *tmr, void *vesdp)
     tmr->btm.proc_tree.parent = ERTS_HLT_PFIELD_NOT_IN_TABLE;
 
     if (sid == (Uint32) esdp->no) {
-	if (state == ERTS_TMR_STATE_ACTIVE)
+	if (state == ERTS_TMR_STATE_ACTIVE) {
+	    if (tmr->btm.bp)
+		free_message_buffer(tmr->btm.bp);
 	    hlt_delete_timer(esdp, tmr);
+	}
 	hl_timer_dec_refc(tmr, roflgs);
     }
     else {
-	if (state == ERTS_TMR_STATE_ACTIVE)
+	if (state == ERTS_TMR_STATE_ACTIVE) {
+	    if (tmr->btm.bp)
+		free_message_buffer(tmr->btm.bp);
 	    queue_canceled_timer(esdp, sid, (ErtsTimer *) tmr);
+	}
 	else
 	    hl_timer_dec_refc(tmr, roflgs);
     }
@@ -2398,7 +2408,7 @@ BIF_RETTYPE send_after_3(BIF_ALIST_3)
     tres = parse_timeout_pos(ERTS_PROC_GET_SCHDATA(BIF_P), BIF_ARG_1, NULL,
 			     0, &timeout_pos, &short_time);
     if (tres != 0)
-	BIF_ERROR(BIF_P, tres < 0 ? BADARG : SYSTEM_LIMIT);
+	BIF_ERROR(BIF_P, BADARG);
 
     return setup_bif_timer(BIF_P, timeout_pos, short_time,
 			   BIF_ARG_2, BIF_ARG_2, BIF_ARG_3, 0);
@@ -2416,7 +2426,7 @@ BIF_RETTYPE send_after_4(BIF_ALIST_4)
     tres = parse_timeout_pos(ERTS_PROC_GET_SCHDATA(BIF_P), BIF_ARG_1, NULL,
 			     abs, &timeout_pos, &short_time);
     if (tres != 0)
-	BIF_ERROR(BIF_P, tres < 0 ? BADARG : SYSTEM_LIMIT);
+	BIF_ERROR(BIF_P, BADARG);
 
     return setup_bif_timer(BIF_P, timeout_pos, short_time,
 			   BIF_ARG_2, accessor, BIF_ARG_3, 0);
@@ -2430,7 +2440,7 @@ BIF_RETTYPE start_timer_3(BIF_ALIST_3)
     tres = parse_timeout_pos(ERTS_PROC_GET_SCHDATA(BIF_P), BIF_ARG_1, NULL,
 			     0, &timeout_pos, &short_time);
     if (tres != 0)
-	BIF_ERROR(BIF_P, tres < 0 ? BADARG : SYSTEM_LIMIT);
+	BIF_ERROR(BIF_P, BADARG);
 
     return setup_bif_timer(BIF_P, timeout_pos, short_time,
 			   BIF_ARG_2, BIF_ARG_2, BIF_ARG_3, !0);
@@ -2448,7 +2458,7 @@ BIF_RETTYPE start_timer_4(BIF_ALIST_4)
     tres = parse_timeout_pos(ERTS_PROC_GET_SCHDATA(BIF_P), BIF_ARG_1, NULL,
 			     abs, &timeout_pos, &short_time);
     if (tres != 0)
-	BIF_ERROR(BIF_P, tres < 0 ? BADARG : SYSTEM_LIMIT);
+	BIF_ERROR(BIF_P, BADARG);
 
     return setup_bif_timer(BIF_P, timeout_pos, short_time,
 			   BIF_ARG_2, accessor, BIF_ARG_3, !0);
diff --git a/erts/emulator/beam/time.c b/erts/emulator/beam/time.c
index ea19d8b362..8bffdedb2b 100644
--- a/erts/emulator/beam/time.c
+++ b/erts/emulator/beam/time.c
@@ -135,39 +135,40 @@ struct ErtsTimerWheel_ {
     ErtsMonotonicTime next_timeout_time;
 };
 
-/* get the time (in units of TIW_ITIME) to the next timeout,
-   or -1 if there are no timeouts                     */
-
 static ERTS_INLINE ErtsMonotonicTime
-find_next_timeout(ErtsTimerWheel *tiw,
-		  ErtsMonotonicTime curr_time,
-		  ErtsMonotonicTime max_search_time)
+find_next_timeout(ErtsSchedulerData *esdp,
+		  ErtsTimerWheel *tiw,
+		  int search_all,
+		  ErtsMonotonicTime curr_time,       /* When !search_all */
+		  ErtsMonotonicTime max_search_time) /* When !search_all */
 {
     int start_ix, tiw_pos_ix;
     ErtsTWheelTimer *p;
-    int true_min_timeout;
+    int true_min_timeout = 0;
     ErtsMonotonicTime min_timeout, min_timeout_pos, slot_timeout_pos;
 
-    if (tiw->true_next_timeout_time)
-	return tiw->next_timeout_time;
-
     if (tiw->nto == 0) { /* no timeouts in wheel */
-	true_min_timeout = 0;
-	min_timeout_pos = ERTS_MONOTONIC_TO_CLKTCKS(curr_time + ERTS_MONOTONIC_DAY);
+	if (!search_all)
+	    min_timeout_pos = tiw->pos;
+	else {
+	    curr_time = erts_get_monotonic_time(esdp);
+	    tiw->pos = min_timeout_pos = ERTS_MONOTONIC_TO_CLKTCKS(curr_time);
+	}
+	min_timeout_pos += ERTS_MONOTONIC_TO_CLKTCKS(ERTS_MONOTONIC_DAY);
 	goto found_next;
     }
 
-    slot_timeout_pos = tiw->pos;
-    min_timeout_pos = ERTS_MONOTONIC_TO_CLKTCKS(curr_time + max_search_time);
+    slot_timeout_pos = min_timeout_pos = tiw->pos;
+    if (search_all)
+	min_timeout_pos += ERTS_MONOTONIC_TO_CLKTCKS(ERTS_MONOTONIC_DAY);
+    else
+	min_timeout_pos = ERTS_MONOTONIC_TO_CLKTCKS(curr_time + max_search_time);
 
     start_ix = tiw_pos_ix = (int) (tiw->pos & (ERTS_TIW_SIZE-1));
 
     do {
-	slot_timeout_pos++;
-	if (slot_timeout_pos >= min_timeout_pos) {
-	    true_min_timeout = 0;
+	if (++slot_timeout_pos >= min_timeout_pos)
 	    break;
-	}
 
 	p = tiw->w[tiw_pos_ix];
 
@@ -269,24 +270,16 @@ remove_timer(ErtsTimerWheel *tiw, ErtsTWheelTimer *p)
 
     p->slot = ERTS_TWHEEL_SLOT_INACTIVE;
 
-#if 0
-    p->next = NULL;
-    p->prev = NULL;
-#endif
-
     tiw->nto--;
 }
 
 ErtsMonotonicTime
 erts_check_next_timeout_time(ErtsSchedulerData *esdp)
 {
-    /*
-     * Called before a scheduler is about to wait. We wont
-     * check more than 10 minutes into the future.
-     */
-    return find_next_timeout(esdp->timer_wheel,
-			     erts_get_monotonic_time(esdp),
-			     ERTS_SEC_TO_MONOTONIC(10*60));
+    ErtsTimerWheel *tiw = esdp->timer_wheel;
+    if (tiw->true_next_timeout_time)
+	return tiw->next_timeout_time;
+    return find_next_timeout(esdp, tiw, 1, 0, 0);
 }
 
 #ifndef ERTS_TW_DEBUG
@@ -330,14 +323,11 @@ timeout_timer(ErtsTWheelTimer *p)
 {
     ErlTimeoutProc timeout;
     void *arg;
-#if 0
-    p->next = NULL;
-    p->prev = NULL;
-#endif
     p->slot = ERTS_TWHEEL_SLOT_INACTIVE;
     timeout = p->u.func.timeout;
     arg = p->u.func.arg;
     (*timeout)(arg);
+    ASSERT_NO_LOCKED_LOCKS;
 }
 
 void
@@ -508,7 +498,7 @@ erts_bump_timers(ErtsTimerWheel *tiw, ErtsMonotonicTime curr_time)
     tiw->next_timeout_time = curr_time + ERTS_MONOTONIC_DAY;
 
     /* Search at most two seconds ahead... */
-    (void) find_next_timeout(tiw, curr_time, ERTS_SEC_TO_MONOTONIC(2));
+    (void) find_next_timeout(NULL, tiw, 0, curr_time, ERTS_SEC_TO_MONOTONIC(2));
 }
 
 Uint
diff --git a/erts/emulator/test/after_SUITE.erl b/erts/emulator/test/after_SUITE.erl
index 699a1436ce..c855481489 100644
--- a/erts/emulator/test/after_SUITE.erl
+++ b/erts/emulator/test/after_SUITE.erl
@@ -27,7 +27,8 @@
 	 init_per_group/2,end_per_group/2, 
 	 t_after/1, receive_after/1, receive_after_big/1,
 	 receive_after_errors/1, receive_var_zero/1, receive_zero/1,
-	 multi_timeout/1, receive_after_32bit/1]).
+	 multi_timeout/1, receive_after_32bit/1,
+	 receive_after_blast/1]).
 
 -export([init_per_testcase/2, end_per_testcase/2]).
 
@@ -40,7 +41,7 @@ suite() -> [{ct_hooks,[ts_install_cth]}].
 all() -> 
     [t_after, receive_after, receive_after_big,
      receive_after_errors, receive_var_zero, receive_zero,
-     multi_timeout, receive_after_32bit].
+     multi_timeout, receive_after_32bit, receive_after_blast].
 
 groups() -> 
     [].
@@ -244,4 +245,26 @@ recv_after_32bit(I, T) when I rem 2 =:= 0 ->
     receive after T -> exit(timeout) end;
 recv_after_32bit(_, _) ->
     receive after 16#ffffFFFF -> exit(timeout) end.
-		    
+
+blaster() ->
+    receive
+	{go, TimeoutTime} ->
+	    Tmo = TimeoutTime - erlang:monotonic_time(milli_seconds),
+	    receive after Tmo -> ok end
+    end.
+
+spawn_blasters(0) ->
+    [];
+spawn_blasters(N) ->
+    [spawn_monitor(fun () -> blaster() end)|spawn_blasters(N-1)].
+
+receive_after_blast(Config) when is_list(Config) ->
+    PMs = spawn_blasters(10000),
+    TimeoutTime = erlang:monotonic_time(milli_seconds) + 5000,
+    lists:foreach(fun ({P, _}) -> P ! {go, TimeoutTime} end, PMs),
+    lists:foreach(fun ({P, M}) ->
+			  receive
+			      {'DOWN', M, process, P, normal} ->
+				  ok
+			  end
+		  end, PMs).
diff --git a/erts/emulator/test/system_info_SUITE.erl b/erts/emulator/test/system_info_SUITE.erl
index 0fd6696536..e3ac2d5d83 100644
--- a/erts/emulator/test/system_info_SUITE.erl
+++ b/erts/emulator/test/system_info_SUITE.erl
@@ -264,6 +264,37 @@ memory_test(_Config) ->
 		     []),
     cmp_memory(MWs, "unlink procs"),
 
+    mem_workers_call(MWs, 
+		     fun () ->
+			     lists:foreach(
+			       fun (P) ->
+				       Tmr = erlang:start_timer(1 bsl 34,
+								P,
+								hello),
+				       Tmrs = case get('BIF_TMRS') of
+						  undefined -> [];
+						  Rs -> Rs
+					      end,
+				       true = is_reference(Tmr),
+				       put('BIF_TMRS', [Tmr|Tmrs])
+			       end, Ps)
+		     end,
+		     []),
+    cmp_memory(MWs, "start BIF timer procs"),
+
+    mem_workers_call(MWs, 
+		     fun () ->
+			     lists:foreach(fun (Tmr) ->
+						   true = is_reference(Tmr),
+						   true = is_integer(erlang:cancel_timer(Tmr))
+					   end, get('BIF_TMRS')),
+			     put('BIF_TMRS', undefined),
+			     garbage_collect()
+		     end,
+		     []),
+    erts_debug:set_internal_state(wait, deallocations),
+    cmp_memory(MWs, "cancel BIF timer procs"),
+
     DMs = mem_workers_call(MWs,
 			   fun () ->
 				   lists:map(fun (P) ->
diff --git a/erts/emulator/test/timer_bif_SUITE.erl b/erts/emulator/test/timer_bif_SUITE.erl
index 3701dd8437..d406456f98 100644
--- a/erts/emulator/test/timer_bif_SUITE.erl
+++ b/erts/emulator/test/timer_bif_SUITE.erl
@@ -26,11 +26,17 @@
 	 cancel_timer_1/1,
 	 start_timer_big/1, send_after_big/1,
 	 start_timer_e/1, send_after_e/1, cancel_timer_e/1,
-	 read_timer_trivial/1, read_timer/1,
-	 cleanup/1, evil_timers/1, registered_process/1]).
+	 read_timer_trivial/1, read_timer/1, read_timer_async/1,
+	 cleanup/1, evil_timers/1, registered_process/1, same_time_yielding/1,
+	 same_time_yielding_with_cancel/1, same_time_yielding_with_cancel_other/1,
+	 same_time_yielding_with_cancel_other_accessor/1, auto_cancel_yielding/1]).
 
 -include_lib("test_server/include/test_server.hrl").
 
+-define(SHORT_TIMEOUT, 5000). %% Bif timers as short as this may be pre-allocated
+-define(TIMEOUT_YIELD_LIMIT, 100).
+-define(AUTO_CANCEL_YIELD_LIMIT, 100).
+
 init_per_testcase(_Case, Config) ->
     ?line Dog=test_server:timetrap(test_server:seconds(30)),
     case catch erts_debug:get_internal_state(available_internal_state) of
@@ -45,6 +51,7 @@ end_per_testcase(_Case, Config) ->
     ok.
 
 init_per_suite(Config) ->
+    erts_debug:set_internal_state(available_internal_state, true),
     Config.
 
 end_per_suite(_Config) ->
@@ -56,8 +63,12 @@ all() ->
     [start_timer_1, send_after_1, send_after_2,
      cancel_timer_1, start_timer_e, send_after_e,
      cancel_timer_e, start_timer_big, send_after_big,
-     read_timer_trivial, read_timer, cleanup, evil_timers,
-     registered_process].
+     read_timer_trivial, read_timer, read_timer_async,
+     cleanup, evil_timers, registered_process,
+     same_time_yielding, same_time_yielding_with_cancel,
+     same_time_yielding_with_cancel_other,
+     same_time_yielding_with_cancel_other_accessor,
+     auto_cancel_yielding].
 
 groups() -> 
     [].
@@ -162,7 +173,7 @@ cancel_timer_1(Config) when is_list(Config) ->
 start_timer_e(doc) -> ["Error cases for start_timer/3"];
 start_timer_e(Config) when is_list(Config) ->
     ?line {'EXIT', _} = (catch erlang:start_timer(-4, self(), hej)),
-    ?line {'EXIT', _} = (catch erlang:start_timer(4728472847827482,
+    ?line {'EXIT', _} = (catch erlang:start_timer(1 bsl 64,
 						  self(), hej)),
 
     ?line {'EXIT', _} = (catch erlang:start_timer(4.5, self(), hej)),
@@ -180,7 +191,7 @@ send_after_e(doc) -> ["Error cases for send_after/3"];
 send_after_e(suite) -> [];
 send_after_e(Config) when is_list(Config) ->
     ?line {'EXIT', _} = (catch erlang:send_after(-4, self(), hej)),
-    ?line {'EXIT', _} = (catch erlang:send_after(4728472847827482,
+    ?line {'EXIT', _} = (catch erlang:send_after(1 bsl 64,
 						 self(), hej)),
 
     ?line {'EXIT', _} = (catch erlang:send_after(4.5, self(), hej)),
@@ -213,44 +224,79 @@ read_timer_trivial(Config) when is_list(Config) ->
 read_timer(doc) -> ["Test that read_timer/1 seems to return the correct values."];
 read_timer(suite) -> [];
 read_timer(Config) when is_list(Config) ->
-    ?line Big = 1 bsl 31,
-    ?line R = erlang:send_after(Big, self(), hej_hopp),
+    process_flag(scheduler, 1),
+    Big = 1 bsl 31,
+    R = erlang:send_after(Big, self(), hej_hopp),
+
+    receive after 200 -> ok end,		% Delay and clear reductions.
+    Left = erlang:read_timer(R),
+    Left2 = erlang:cancel_timer(R),
+    case Left == Left2 of
+	true -> ok;
+	false -> Left = Left2 + 1
+    end,
+    false = erlang:read_timer(R),
 
-    ?line receive after 200 -> ok end,		% Delay and clear reductions.
-    ?line Left = erlang:read_timer(R),
-    ?line Left = erlang:cancel_timer(R),
-    ?line false = erlang:read_timer(R),
+    case Big - Left of
+	Diff when Diff >= 200, Diff < 10000 ->
+	    ok;
+	_Diff ->
+	    test_server:fail({big, Big, Left})
+    end,
+    process_flag(scheduler, 0),
+    ok.
 
-    ?line case Big - Left of
-	      Diff when Diff >= 200, Diff < 10000 ->
-		  ok;
-	      _Diff ->
-		  test_server:fail({big, Big, Left})
-	  end,
+read_timer_async(doc) -> ["Test that read_timer/1 seems to return the correct values."];
+read_timer_async(suite) -> [];
+read_timer_async(Config) when is_list(Config) ->
+    process_flag(scheduler, 1),
+    Big = 1 bsl 33,
+    R = erlang:send_after(Big, self(), hej_hopp),
+
+    %% Access from another scheduler
+    process_flag(scheduler, erlang:system_info(schedulers_online)),
+
+    receive after 200 -> ok end,		% Delay and clear reductions.
+    ok = erlang:read_timer(R, [{async, true}]),
+    ok = erlang:cancel_timer(R, [{async, true}, {info, true}]),
+    ok = erlang:read_timer(R, [{async, true}]),
+
+    {read_timer, R, Left} = receive_one(),
+    {cancel_timer, R, Left2} = receive_one(),
+    case Left == Left2 of
+	true -> ok;
+	false -> Left = Left2 + 1
+    end,
+    {read_timer, R, false} = receive_one(),
+
+    case Big - Left of
+	Diff when Diff >= 200, Diff < 10000 ->
+	    ok;
+	_Diff ->
+	    test_server:fail({big, Big, Left})
+    end,
+    process_flag(scheduler, 0),
     ok.
 
 cleanup(doc) -> [];
 cleanup(suite) -> [];
 cleanup(Config) when is_list(Config) ->
-    {skipped, "Test needs to be UPDATED for new timer implementation"}.
-
-cleanup_test(Config) when is_list(Config) ->
     ?line Mem = mem(),
     %% Timer on dead process
     ?line P1 = spawn(fun () -> ok end),
     ?line wait_until(fun () -> process_is_cleaned_up(P1) end),
-    ?line T1 = erlang:start_timer(10000, P1, "hej"),
-    ?line T2 = erlang:send_after(10000, P1, "hej"),
+    ?line T1 = erlang:start_timer(?SHORT_TIMEOUT*2, P1, "hej"),
+    ?line T2 = erlang:send_after(?SHORT_TIMEOUT*2, P1, "hej"),
     receive after 1000 -> ok end,
     ?line Mem = mem(),
     ?line false = erlang:read_timer(T1),
     ?line false = erlang:read_timer(T2),
     ?line Mem = mem(),
     %% Process dies before timeout
-    ?line P2 = spawn(fun () -> receive after 500 -> ok end end),
-    ?line T3 = erlang:start_timer(10000, P2, "hej"),
-    ?line T4 = erlang:send_after(10000, P2, "hej"),
-    ?line true = Mem < mem(),
+    ?line P2 = spawn(fun () -> receive after (?SHORT_TIMEOUT div 10) -> ok end end),
+    ?line T3 = erlang:start_timer(?SHORT_TIMEOUT*2, P2, "hej"),
+    ?line T4 = erlang:send_after(?SHORT_TIMEOUT*2, P2, "hej"),
+    ?line true = mem_larger_than(Mem),
     ?line true = is_integer(erlang:read_timer(T3)),
     ?line true = is_integer(erlang:read_timer(T4)),
     ?line wait_until(fun () -> process_is_cleaned_up(P2) end),
@@ -259,21 +305,22 @@ cleanup_test(Config) when is_list(Config) ->
     ?line false = erlang:read_timer(T4),
     ?line Mem = mem(),
     %% Cancel timer
-    ?line P3 = spawn(fun () -> receive after 20000 -> ok end end),
-    ?line T5 = erlang:start_timer(10000, P3, "hej"),
-    ?line T6 = erlang:send_after(10000, P3, "hej"),
-    ?line true = Mem < mem(),
+    ?line P3 = spawn(fun () -> receive after ?SHORT_TIMEOUT*4 -> ok end end),
+    ?line T5 = erlang:start_timer(?SHORT_TIMEOUT*2, P3, "hej"),
+    ?line T6 = erlang:send_after(?SHORT_TIMEOUT*2, P3, "hej"),
+    ?line true = mem_larger_than(Mem),
     ?line true = is_integer(erlang:cancel_timer(T5)),
     ?line true = is_integer(erlang:cancel_timer(T6)),
     ?line false = erlang:read_timer(T5),
     ?line false = erlang:read_timer(T6),
     ?line exit(P3, kill),
+    ?line wait_until(fun () -> process_is_cleaned_up(P3) end),
     ?line Mem = mem(),
     %% Timeout
     ?line Ref = make_ref(),
-    ?line T7 = erlang:start_timer(500, self(), Ref),
-    ?line T8 = erlang:send_after(500, self(), Ref),
-    ?line true = Mem < mem(),
+    ?line T7 = erlang:start_timer(?SHORT_TIMEOUT+1, self(), Ref),
+    ?line T8 = erlang:send_after(?SHORT_TIMEOUT+1, self(), Ref),
+    ?line true = mem_larger_than(Mem),
     ?line true = is_integer(erlang:read_timer(T7)),
     ?line true = is_integer(erlang:read_timer(T8)),
     ?line receive {timeout, T7, Ref} -> ok end,
@@ -423,15 +470,12 @@ evil_recv_timeouts(TOs, N, M) ->
 registered_process(doc) -> [];
 registered_process(suite) -> [];
 registered_process(Config) when is_list(Config) ->
-    {skipped, "Test needs to be UPDATED for new timer implementation"}.
-
-registered_process_test(Config)  when is_list(Config) ->
     ?line Mem = mem(),
     %% Cancel
-    ?line T1 = erlang:start_timer(500, ?MODULE, "hej"),
-    ?line T2 = erlang:send_after(500, ?MODULE, "hej"),
+    ?line T1 = erlang:start_timer(?SHORT_TIMEOUT+1, ?MODULE, "hej"),
+    ?line T2 = erlang:send_after(?SHORT_TIMEOUT+1, ?MODULE, "hej"),
     ?line undefined = whereis(?MODULE),
-    ?line true = Mem < mem(),
+    ?line true = mem_larger_than(Mem),
     ?line true = is_integer(erlang:cancel_timer(T1)),
     ?line true = is_integer(erlang:cancel_timer(T2)),
     ?line false = erlang:read_timer(T1),
@@ -439,10 +483,10 @@ registered_process_test(Config)  when is_list(Config) ->
     ?line Mem = mem(),
     %% Timeout register after start
     ?line Ref1 = make_ref(),
-    ?line T3 = erlang:start_timer(500, ?MODULE, Ref1),
-    ?line T4 = erlang:send_after(500, ?MODULE, Ref1),
+    ?line T3 = erlang:start_timer(?SHORT_TIMEOUT+1, ?MODULE, Ref1),
+    ?line T4 = erlang:send_after(?SHORT_TIMEOUT+1, ?MODULE, Ref1),
     ?line undefined = whereis(?MODULE),
-    ?line true = Mem < mem(),
+    ?line true = mem_larger_than(Mem),
     ?line true = is_integer(erlang:read_timer(T3)),
     ?line true = is_integer(erlang:read_timer(T4)),
     ?line true = register(?MODULE, self()),
@@ -451,9 +495,9 @@ registered_process_test(Config)  when is_list(Config) ->
     ?line Mem = mem(),
     %% Timeout register before start
     ?line Ref2 = make_ref(),
-    ?line T5 = erlang:start_timer(500, ?MODULE, Ref2),
-    ?line T6 = erlang:send_after(500, ?MODULE, Ref2),
-    ?line true = Mem < mem(),
+    ?line T5 = erlang:start_timer(?SHORT_TIMEOUT+1, ?MODULE, Ref2),
+    ?line T6 = erlang:send_after(?SHORT_TIMEOUT+1, ?MODULE, Ref2),
+    ?line true = mem_larger_than(Mem),
     ?line true = is_integer(erlang:read_timer(T5)),
     ?line true = is_integer(erlang:read_timer(T6)),
     ?line receive {timeout, T5, Ref2} -> ok end,
@@ -462,19 +506,135 @@ registered_process_test(Config)  when is_list(Config) ->
     ?line true = unregister(?MODULE),
     ?line ok.
 
-mem() ->
-    TSrvs = erts_internal:get_bif_timer_servers(),
-    lists:foldl(fun (Tab, Sz) ->
-			case lists:member(ets:info(Tab, owner), TSrvs) of
-			    true ->
-				ets:info(Tab, memory) + Sz;
-			    false ->
-				Sz
-			end
-		end,
-		0,
-		ets:all())*erlang:system_info({wordsize,external}).
-					    
+same_time_yielding(Config) when is_list(Config) ->
+    Mem = mem(),
+    SchdlrsOnln = erlang:system_info(schedulers_online),
+    Tmo = erlang:monotonic_time(milli_seconds) + 3000,
+    Tmrs = lists:map(fun (I) ->
+			     process_flag(scheduler, (I rem SchdlrsOnln) + 1),
+			     erlang:start_timer(Tmo, self(), hej, [{abs, true}])
+		     end,
+		     lists:seq(1, (?TIMEOUT_YIELD_LIMIT*3+1)*SchdlrsOnln)),
+    true = mem_larger_than(Mem),
+    lists:foreach(fun (Tmr) -> receive {timeout, Tmr, hej} -> ok end end, Tmrs),
+    Done = erlang:monotonic_time(milli_seconds),
+    true = Done >= Tmo,
+    case erlang:system_info(build_type) of
+	opt -> true = Done < Tmo + 200;
+	_ -> true = Done < Tmo + 1000
+    end,
+    Mem = mem(),
+    ok.
+
+same_time_yielding_with_cancel(Config) when is_list(Config) ->
+    same_time_yielding_with_cancel_test(false, false).
+
+same_time_yielding_with_cancel_other(Config) when is_list(Config) ->
+    same_time_yielding_with_cancel_test(true, false).
+
+same_time_yielding_with_cancel_other_accessor(Config) when is_list(Config) ->
+    same_time_yielding_with_cancel_test(true, true).
+
+do_cancel_tmrs(Tmo, Tmrs, Tester) ->
+    BeginCancel = erlang:convert_time_unit(Tmo,
+					   milli_seconds,
+					   micro_seconds) - 100,
+    busy_wait_until(fun () ->
+			    erlang:monotonic_time(micro_seconds) >= BeginCancel
+		    end),
+    lists:foreach(fun (Tmr) ->
+			  erlang:cancel_timer(Tmr,
+					      [{async, true},
+					       {info, true}])
+		  end, Tmrs),
+    case Tester == self() of
+	true -> ok;
+	false -> forward_msgs(Tester)
+    end.
+
+same_time_yielding_with_cancel_test(Other, Accessor) ->
+    Mem = mem(),
+    SchdlrsOnln = erlang:system_info(schedulers_online),
+    Tmo = erlang:monotonic_time(milli_seconds) + 3000,
+    Tester = self(),
+    Cancelor = case Other of
+		   false ->
+		       Tester;
+		   true ->
+		       spawn(fun () ->
+				     receive
+					 {timers, Tmrs} ->
+					     do_cancel_tmrs(Tmo, Tmrs, Tester)
+				     end
+			     end)
+	       end,
+    Opts = case Accessor of
+	       false -> [{abs, true}];
+	       true -> [{accessor, Cancelor}, {abs, true}]
+	   end,
+    Tmrs = lists:map(fun (I) ->
+			     process_flag(scheduler, (I rem SchdlrsOnln) + 1),
+			     erlang:start_timer(Tmo, self(), hej, Opts)
+		     end,
+		     lists:seq(1, (?TIMEOUT_YIELD_LIMIT*3+1)*SchdlrsOnln)),
+    true = mem_larger_than(Mem),
+    case Other of
+	false ->
+	    do_cancel_tmrs(Tmo, Tmrs, Tester);
+	true ->
+	    Cancelor ! {timers, Tmrs}
+    end,
+    {Tmos, Cncls} = lists:foldl(fun (Tmr, {T, C}) ->
+					receive
+					    {timeout, Tmr, hej} ->
+						receive
+						    {cancel_timer, Tmr, Info} ->
+							false = Info,
+							{T+1, C}
+						end;
+					    {cancel_timer, Tmr, false} ->
+						receive
+						    {timeout, Tmr, hej} ->
+							{T+1, C}
+						end;
+					    {cancel_timer, Tmr, TimeLeft} ->
+						true = is_integer(TimeLeft),
+						{T, C+1}
+					end
+				end,
+				{0, 0},
+				Tmrs),
+    io:format("Timeouts: ~p Cancels: ~p~n", [Tmos, Cncls]),
+    Mem = mem(),
+    case Other of
+	true -> exit(Cancelor, bang);
+	false -> ok
+    end,
+    {comment,
+     "Timeouts: " ++ integer_to_list(Tmos) ++ " Cancels: "
+     ++ integer_to_list(Cncls)}.
+
+auto_cancel_yielding(Config) when is_list(Config) ->
+    Mem = mem(),
+    SchdlrsOnln = erlang:system_info(schedulers_online),
+    P = spawn(fun () ->
+		      lists:foreach(
+			fun (I) ->
+				process_flag(scheduler, (I rem SchdlrsOnln)+1),
+				erlang:start_timer((1 bsl 28)+I*10, self(), hej)
+			end,
+			lists:seq(1,
+				  ((?AUTO_CANCEL_YIELD_LIMIT*3+1)
+				   *SchdlrsOnln))),
+		      receive after infinity -> ok end
+	      end),
+    true = mem_larger_than(Mem),
+    exit(P, bang),
+    wait_until(fun () -> process_is_cleaned_up(P) end),
+    receive after 1000 -> ok end,
+    Mem = mem(),
+    ok.
+
 process_is_cleaned_up(P) when is_pid(P) ->
     undefined == erts_debug:get_internal_state({process_status, P}).
 
@@ -484,6 +644,19 @@ wait_until(Pred) when is_function(Pred) ->
 	_ -> receive after 50 -> ok end, wait_until(Pred)
     end.
 
+busy_wait_until(Pred) when is_function(Pred) ->
+    case catch Pred() of
+	true -> ok;
+	_ -> busy_wait_until(Pred)
+    end.
+
+forward_msgs(To) ->
+    receive
+	Msg ->
+	    To ! Msg
+    end,
+    forward_msgs(To).
+
 get(Time, Msg) ->
     receive 
 	Msg ->
@@ -566,5 +739,58 @@ type(X) when is_port(X) -> {port, node(X)};
 type(X) when is_binary(X) -> binary;
 type(X) when is_atom(X) -> atom;
 type(_) -> unknown.
-    
 
+
+mem_larger_than(no_fix_alloc) ->
+    true;
+mem_larger_than(Mem) ->
+    mem() > Mem.
+
+mem() ->
+    erts_debug:set_internal_state(wait, deallocations),
+    erts_debug:set_internal_state(wait, deallocations),
+    case mem_get() of
+	{-1, -1} -> no_fix_alloc;
+	{A, U} -> io:format("mem = ~p ~p~n", [A, U]), U
+    end.
+
+mem_get() ->
+    % Bif timer memory
+    Ref = make_ref(),
+    erlang:system_info({memory_internal, Ref, [fix_alloc]}),
+    mem_recv(erlang:system_info(schedulers), Ref, {0, 0}).
+
+mem_recv(0, _Ref, AU) ->
+    AU;
+mem_recv(N, Ref, AU) ->
+    receive
+	{Ref, _, IL} ->
+	    mem_recv(N-1, Ref, mem_parse_ilists(IL, AU))
+    end.
+
+
+mem_parse_ilists([], AU) ->
+    AU;
+mem_parse_ilists([I|Is], AU) ->
+    mem_parse_ilists(Is, mem_parse_ilist(I, AU)).
+
+mem_parse_ilist({fix_alloc, false}, _) ->
+    {-1, -1};
+mem_parse_ilist({fix_alloc, _, IDL}, {A, U}) ->
+    case lists:keyfind(fix_types, 1, IDL) of
+	{fix_types, TL} ->
+	    {ThisA, ThisU} = mem_get_btm_aus(TL, 0, 0),
+	    {ThisA + A, ThisU + U};
+	{fix_types, Mask, TL} ->
+	    {ThisA, ThisU} = mem_get_btm_aus(TL, 0, 0),
+	    {(ThisA + A) band Mask , (ThisU + U) band Mask}
+    end.
+
+mem_get_btm_aus([], A, U) ->
+    {A, U};
+mem_get_btm_aus([{BtmType, BtmA, BtmU} | Types],
+	    A, U) when BtmType == bif_timer;
+		       BtmType == accessor_bif_timer ->
+    mem_get_btm_aus(Types, BtmA+A, BtmU+U);
+mem_get_btm_aus([_|Types], A, U) ->
+    mem_get_btm_aus(Types, A, U).
diff --git a/erts/preloaded/ebin/erlang.beam b/erts/preloaded/ebin/erlang.beam
index ce61199567..aa9d8ae4fe 100644
--- a/erts/preloaded/ebin/erlang.beam
+++ b/erts/preloaded/ebin/erlang.beam
diff --git a/erts/preloaded/src/erlang.erl b/erts/preloaded/src/erlang.erl
index 4ef4288ead..ea8a911a2c 100644
--- a/erts/preloaded/src/erlang.erl
+++ b/erts/preloaded/src/erlang.erl
@@ -425,19 +425,23 @@ call_on_load_function(_P1) ->
     erlang:nif_error(undefined).
 
 %% cancel_timer/1
--spec erlang:cancel_timer(TimerRef) -> Time | false when
+-spec erlang:cancel_timer(TimerRef) -> Result when
       TimerRef :: reference(),
-      Time :: non_neg_integer().
+      Time :: non_neg_integer(),
+      Result :: Time | false.
 
 cancel_timer(_TimerRef) ->
     erlang:nif_error(undefined).
 
 %% cancel_timer/2
--spec erlang:cancel_timer(TimerRef, Options) -> Time | false | ok when
+-spec erlang:cancel_timer(TimerRef, Options) -> Result | ok when
       TimerRef :: reference(),
-      Option :: {async, boolean()} | {info, boolean()},
+      Async :: boolean(),
+      Info :: boolean(),
+      Option :: {async, Async} | {info, Info},
       Options :: [Option],
-      Time :: non_neg_integer().
+      Time :: non_neg_integer(),
+      Result :: Time | false.
 
 cancel_timer(_TimerRef, _Options) ->
     erlang:nif_error(undefined).
@@ -1478,17 +1482,22 @@ raise(_Class, _Reason, _Stacktrace) ->
     erlang:nif_error(undefined).
 
 %% read_timer/1
--spec erlang:read_timer(TimerRef) -> non_neg_integer() | false when
-      TimerRef :: reference().
+-spec erlang:read_timer(TimerRef) -> Result when
+      TimerRef :: reference(),
+      Time :: non_neg_integer(),
+      Result :: Time | false.
 
 read_timer(_TimerRef) ->
     erlang:nif_error(undefined).
 
 %% read_timer/2
--spec erlang:read_timer(TimerRef, Options) -> non_neg_integer() | false | ok when
+-spec erlang:read_timer(TimerRef, Options) -> Result | ok when
       TimerRef :: reference(),
-      Option :: {async, boolean()},
-      Options :: [Option].
+      Async :: boolean(),
+      Option :: {async, Async},
+      Options :: [Option],
+      Time :: non_neg_integer(),
+      Result :: Time | false.
 
 read_timer(_TimerRef, _Options) ->
     erlang:nif_error(undefined).
@@ -1547,7 +1556,8 @@ send_after(_Time, _Dest, _Msg) ->
       Dest :: pid() | atom(),
       Msg :: term(),
       Options :: [Option],
-      Option :: {abs, boolean()} | {accessor, pid()},
+      Abs :: boolean(),
+      Option :: {abs, Abs}, %% | {accessor, Accessor} undocumented feature for now,
       TimerRef :: reference().
 
 send_after(_Time, _Dest, _Msg, _Options) ->
@@ -1634,7 +1644,8 @@ start_timer(_Time, _Dest, _Msg) ->
       Dest :: pid() | atom(),
       Msg :: term(),
       Options :: [Option],
-      Option :: {abs, boolean()} | {accessor, pid()},
+      Abs :: boolean(),
+      Option :: {abs, Abs}, %% | {accessor, Accessor} undocumented feature for now,
       TimerRef :: reference().
 
 start_timer(_Time, _Dest, _Msg, _Options) ->
@@ -3589,7 +3600,11 @@ blocks_size([], Acc) ->
 get_fix_proc([{ProcType, A1, U1}| Rest], {A0, U0}) when ProcType == proc;
 							ProcType == monitor_sh;
 							ProcType == nlink_sh;
-							ProcType == msg_ref ->
+							ProcType == msg_ref;
+							ProcType == ll_ptimer;
+							ProcType == hl_ptimer;
+							ProcType == bif_timer;
+							ProcType == accessor_bif_timer ->
     get_fix_proc(Rest, {A0+A1, U0+U1});
 get_fix_proc([_|Rest], Acc) ->
     get_fix_proc(Rest, Acc);