Better OS system time implementation

8 files changed, 350 insertions, 125 deletions

diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 70062b2305..8491c01b75 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -2120,6 +2120,8 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
 	}
     } 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("os_system_time_source", BIF_ARG_1)) {
+	BIF_RET(erts_system_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)) {
diff --git a/erts/emulator/beam/erl_time.h b/erts/emulator/beam/erl_time.h
index 35a1442dbd..7f8c4e0ed5 100644
--- a/erts/emulator/beam/erl_time.h
+++ b/erts/emulator/beam/erl_time.h
@@ -148,6 +148,7 @@ 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);
+Eterm erts_system_time_source(struct process*c_p);
 
 #ifdef SYS_CLOCK_RESOLUTION
 #define ERTS_CLKTCK_RESOLUTION ((ErtsMonotonicTime) (SYS_CLOCK_RESOLUTION*1000))
diff --git a/erts/emulator/beam/erl_time_sup.c b/erts/emulator/beam/erl_time_sup.c
index d961fae81a..ef39f4b5f4 100644
--- a/erts/emulator/beam/erl_time_sup.c
+++ b/erts/emulator/beam/erl_time_sup.c
@@ -133,12 +133,17 @@ struct time_sup_read_only__ {
     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;
-    Uint64 os_monotonic_extended;
+    int os_monotonic_time_disable;
+    char *os_monotonic_time_func;
+    char *os_monotonic_time_clock_id;
+    int os_monotonic_time_locked;
+    Uint64 os_monotonic_time_resolution;
+    Uint64 os_monotonic_time_extended;
+    char *os_system_time_func;
+    char *os_system_time_clock_id;
+    int os_system_time_locked;
+    Uint64 os_system_time_resolution;
+    Uint64 os_system_time_extended;
 #endif
 #if !ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT
     ErtsMonotonicTime start;
@@ -209,7 +214,7 @@ struct time_sup_infrequently_changed__ {
     ErtsMonotonicTime minit;
 #endif
     int finalized_offset;
-    SysTimeval inittv; /* Used everywhere, the initial time-of-day */
+    ErtsSystemTime sinit;
     ErtsMonotonicTime not_corrected_moffset;
     erts_atomic64_t offset;
 };
@@ -242,10 +247,8 @@ ErtsTimeSupData erts_time_sup__ erts_align_attribute(ERTS_CACHE_LINE_SIZE);
 erts_approx_time_t
 erts_get_approx_time(void)
 {
-    SysTimeval tv;
-    sys_gettimeofday(&tv);
-
-    return (erts_approx_time_t) tv.tv_sec;
+    ErtsSystemTime stime = erts_os_system_time();
+    return (erts_approx_time_t) ERTS_MONOTONIC_TO_SEC(stime);
 }
 
 static ERTS_INLINE void
@@ -403,7 +406,6 @@ check_time_correction(void *unused)
     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);
@@ -411,7 +413,7 @@ check_time_correction(void *unused)
     ASSERT(time_sup.inf.c.finalized_offset);
 
     os_mtime = erts_os_monotonic_time();
-    sys_gettimeofday(&tod);
+    os_stime = erts_os_system_time();
 
     cdata = time_sup.inf.c.parmon.cdata;
 
@@ -426,9 +428,6 @@ check_time_correction(void *unused)
     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;
@@ -686,7 +685,6 @@ init_check_time_correction(void *unused)
     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;
@@ -694,10 +692,7 @@ init_check_time_correction(void *unused)
     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);
+    stime = erts_os_system_time();
 
     mtime_diff = mtime - old_mtime;
     stime_diff = stime - old_stime;
@@ -729,7 +724,7 @@ init_check_time_correction(void *unused)
 #endif
 
 static ErtsMonotonicTime
-finalize_corrected_time_offset(SysTimeval *todp)
+finalize_corrected_time_offset(ErtsSystemTime *stimep)
 {
     ErtsMonotonicTime os_mtime;
     ErtsMonotonicCorrectionData cdata;
@@ -738,7 +733,7 @@ finalize_corrected_time_offset(SysTimeval *todp)
     erts_smp_rwmtx_rlock(&time_sup.inf.c.parmon.rwmtx);
 
     os_mtime = erts_os_monotonic_time();
-    sys_gettimeofday(todp);
+    *stimep = erts_os_system_time();
 
     cdata = time_sup.inf.c.parmon.cdata;
 
@@ -774,15 +769,11 @@ late_init_time_correction(void)
 
 static ErtsMonotonicTime get_not_corrected_time(void)
 {
-    SysTimeval tmp_tv;
     ErtsMonotonicTime stime, mtime;
 
     erts_smp_mtx_lock(&erts_get_time_mtx);
 
-    sys_gettimeofday(&tmp_tv);
-
-    stime = ERTS_SEC_TO_MONOTONIC(tmp_tv.tv_sec);
-    stime += ERTS_USEC_TO_MONOTONIC(tmp_tv.tv_usec);
+    stime = erts_os_system_time();
 
     mtime = stime - time_sup.inf.c.not_corrected_moffset;
 
@@ -820,7 +811,7 @@ int erts_check_time_adj_support(int time_correction,
     /* User wants time correction */
 
 #ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
-    return !time_sup.r.o.os_monotonic_disable;
+    return !time_sup.r.o.os_monotonic_time_disable;
 #else
     return 0;
 #endif
@@ -849,24 +840,33 @@ void erts_init_sys_time_sup(void)
 #endif
 
 #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;
-    time_sup.r.o.os_monotonic_extended
-	= sys_init_time_res.os_monotonic_info.extended;
+    time_sup.r.o.os_monotonic_time_disable
+	= !sys_init_time_res.have_os_monotonic_time;
+    time_sup.r.o.os_monotonic_time_func
+	= sys_init_time_res.os_monotonic_time_info.func;
+    time_sup.r.o.os_monotonic_time_clock_id
+	= sys_init_time_res.os_monotonic_time_info.clock_id;
+    time_sup.r.o.os_monotonic_time_locked
+	= sys_init_time_res.os_monotonic_time_info.locked_use;
+    time_sup.r.o.os_monotonic_time_resolution
+	= sys_init_time_res.os_monotonic_time_info.resolution;
+    time_sup.r.o.os_monotonic_time_extended
+	= sys_init_time_res.os_monotonic_time_info.extended;
+    time_sup.r.o.os_system_time_func
+	= sys_init_time_res.os_system_time_info.func;
+    time_sup.r.o.os_system_time_clock_id
+	= sys_init_time_res.os_system_time_info.clock_id;
+    time_sup.r.o.os_system_time_locked
+	= sys_init_time_res.os_system_time_info.locked_use;
+    time_sup.r.o.os_system_time_resolution
+	= sys_init_time_res.os_system_time_info.resolution;
 #endif
 }
 
 int 
 erts_init_time_sup(int time_correction, ErtsTimeWarpMode time_warp_mode)
 {
+    ErtsMonotonicTime resolution;
 #if !ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT
     ErtsMonotonicTime abs_native_offset, native_offset;
 #endif
@@ -935,11 +935,15 @@ erts_init_time_sup(int time_correction, ErtsTimeWarpMode time_warp_mode)
 
 #endif
 
+    resolution = time_sup.r.o.os_monotonic_time_resolution;
+    if (resolution > time_sup.r.o.os_system_time_resolution)
+	resolution = time_sup.r.o.os_system_time_resolution;
+
     time_sup.r.o.adj.large_diff = erts_time_sup__.r.o.monotonic_time_unit;
     time_sup.r.o.adj.large_diff *= 50;
-    time_sup.r.o.adj.large_diff /= time_sup.r.o.os_monotonic_resolution;
-    if (time_sup.r.o.adj.large_diff < ERTS_MSEC_TO_MONOTONIC(5))
-	time_sup.r.o.adj.large_diff = ERTS_MSEC_TO_MONOTONIC(5);
+    time_sup.r.o.adj.large_diff /= resolution;
+    if (time_sup.r.o.adj.large_diff < ERTS_USEC_TO_MONOTONIC(500))
+	time_sup.r.o.adj.large_diff = ERTS_USEC_TO_MONOTONIC(500);
     time_sup.r.o.adj.small_diff = time_sup.r.o.adj.large_diff/10;
 
 #ifdef ERTS_TIME_CORRECTION_PRINT
@@ -961,7 +965,7 @@ erts_init_time_sup(int time_correction, ErtsTimeWarpMode time_warp_mode)
 #ifndef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
     time_sup.r.o.correction = 0;
 #else
-    if (time_sup.r.o.os_monotonic_disable)
+    if (time_sup.r.o.os_monotonic_time_disable)
 	time_sup.r.o.correction = 0;
 
     if (time_sup.r.o.correction) {
@@ -969,10 +973,9 @@ erts_init_time_sup(int time_correction, ErtsTimeWarpMode time_warp_mode)
 	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.inf.c.sinit = erts_os_system_time();
 	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);
+	offset = time_sup.inf.c.sinit;
 	offset -= ERTS_MONOTONIC_TIME_UNIT;
 	init_time_offset(offset);
 
@@ -985,10 +988,7 @@ erts_init_time_sup(int time_correction, ErtsTimeWarpMode time_warp_mode)
 	cdatap = &time_sup.inf.c.parmon.cdata;
     
 #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.sys = time_sup.inf.c.sinit;
 	cdatap->drift.intervals[0].time.mon = time_sup.inf.c.minit;
 	cdatap->curr.correction.drift = 0;
 #endif
@@ -1006,9 +1006,7 @@ erts_init_time_sup(int time_correction, ErtsTimeWarpMode time_warp_mode)
     {
 	ErtsMonotonicTime stime, offset;
 	time_sup.r.o.get_time = get_not_corrected_time;
-	sys_gettimeofday(&time_sup.inf.c.inittv);
-	stime = ERTS_SEC_TO_MONOTONIC(time_sup.inf.c.inittv.tv_sec);
- 	stime += ERTS_USEC_TO_MONOTONIC(time_sup.inf.c.inittv.tv_usec);
+	stime = time_sup.inf.c.sinit = erts_os_system_time();
 	offset = stime - ERTS_MONOTONIC_TIME_UNIT;
 	time_sup.inf.c.not_corrected_moffset = offset;
 	init_time_offset(offset);
@@ -1085,17 +1083,12 @@ erts_finalize_time_offset(void)
 
 	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);
+		ErtsMonotonicTime stime = erts_os_system_time();
 
 		mtime = stime - time_sup.inf.c.not_corrected_moffset;
 
@@ -1114,11 +1107,9 @@ erts_finalize_time_offset(void)
 	    }
 #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;
-
+		ErtsSystemTime stime;
+		mtime = finalize_corrected_time_offset(&stime);
+		new_offset = stime - mtime;
 	    }
 #endif
 	    new_offset = ERTS_MONOTONIC_TO_USEC(new_offset);
@@ -1613,13 +1604,16 @@ erts_get_monotonic_time(void)
 void
 get_sys_now(Uint* megasec, Uint* sec, Uint* microsec)
 {
-    SysTimeval now;
-    
-    sys_gettimeofday(&now);
-    
-    *megasec = (Uint) (now.tv_sec / 1000000);
-    *sec = (Uint) (now.tv_sec % 1000000);
-    *microsec = (Uint) (now.tv_usec);
+    ErtsSystemTime stime = erts_os_system_time();
+    ErtsSystemTime ms, s, us;
+
+    us = ERTS_MONOTONIC_TO_USEC(stime);
+    s = us / (1000*1000);
+    ms = s / (1000*1000);
+
+    *megasec = (Uint) ms;
+    *sec = (Uint) (s - ms*(1000*1000));
+    *microsec = (Uint) (us - s*(1000*1000));
 }
 
 #ifdef HAVE_ERTS_NOW_CPU
@@ -1848,25 +1842,28 @@ bld_monotonic_time_source(Uint **hpp, Uint *szp, Sint64 os_mtime)
     Eterm k[6];
     Eterm v[6];
 
-    if (time_sup.r.o.os_monotonic_disable)
+    if (time_sup.r.o.os_monotonic_time_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);
+    v[i++] = erts_bld_atom(hpp, szp,
+			   time_sup.r.o.os_monotonic_time_func);
 
-    if (time_sup.r.o.os_monotonic_clock_id) {
+    if (time_sup.r.o.os_monotonic_time_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);
+	v[i++] = erts_bld_atom(hpp, szp,
+			       time_sup.r.o.os_monotonic_time_clock_id);
     }
 
     k[i] = erts_bld_atom(hpp, szp, "resolution");
-    v[i++] = erts_bld_uint64(hpp, szp, time_sup.r.o.os_monotonic_resolution);
+    v[i++] = erts_bld_uint64(hpp, szp,
+			     time_sup.r.o.os_monotonic_time_resolution);
 
     k[i] = erts_bld_atom(hpp, szp, "extended");
-    v[i++] = time_sup.r.o.os_monotonic_extended ? am_yes : am_no;
+    v[i++] = time_sup.r.o.os_monotonic_time_extended ? am_yes : am_no;
 
     k[i] = erts_bld_atom(hpp, szp, "parallel");
-    v[i++] = time_sup.r.o.os_monotonic_locked ? am_no : am_yes;
+    v[i++] = time_sup.r.o.os_monotonic_time_locked ? am_no : am_yes;
 
     k[i] = erts_bld_atom(hpp, szp, "time");
     v[i++] = erts_bld_sint64(hpp, szp, os_mtime);
@@ -1882,7 +1879,7 @@ erts_monotonic_time_source(struct process *c_p)
     Eterm *hp = NULL;
     Sint64 os_mtime = 0;
 #ifdef ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT
-    if (!time_sup.r.o.os_monotonic_disable)
+    if (!time_sup.r.o.os_monotonic_time_disable)
 	os_mtime = (Sint64) erts_os_monotonic_time();
 #endif
 
@@ -1892,6 +1889,49 @@ erts_monotonic_time_source(struct process *c_p)
     return bld_monotonic_time_source(&hp, NULL, os_mtime);
 }
 
+static Eterm
+bld_system_time_source(Uint **hpp, Uint *szp, Sint64 os_stime)
+{
+    int i = 0;
+    Eterm k[5];
+    Eterm v[5];
+
+    k[i] = erts_bld_atom(hpp, szp, "function");
+    v[i++] = erts_bld_atom(hpp, szp,
+			   time_sup.r.o.os_system_time_func);
+
+    if (time_sup.r.o.os_system_time_clock_id) {
+	k[i] = erts_bld_atom(hpp, szp, "clock_id");
+	v[i++] = erts_bld_atom(hpp, szp,
+			       time_sup.r.o.os_system_time_clock_id);
+    }
+
+    k[i] = erts_bld_atom(hpp, szp, "resolution");
+    v[i++] = erts_bld_uint64(hpp, szp,
+			     time_sup.r.o.os_system_time_resolution);
+
+    k[i] = erts_bld_atom(hpp, szp, "parallel");
+    v[i++] = am_yes;
+
+    k[i] = erts_bld_atom(hpp, szp, "time");
+    v[i++] = erts_bld_sint64(hpp, szp, os_stime);
+
+    return erts_bld_2tup_list(hpp, szp, (Sint) i, k, v);
+}
+
+Eterm
+erts_system_time_source(struct process *c_p)
+{
+    Uint hsz = 0;
+    Eterm *hp = NULL;
+    Sint64 os_stime = (Sint64) erts_os_system_time();
+
+    bld_system_time_source(NULL, &hsz, os_stime);
+    if (hsz)
+	hp = HAlloc(c_p, hsz);
+    return bld_system_time_source(&hp, NULL, os_stime);
+}
+
 
 #include "bif.h"
 
@@ -2066,21 +2106,13 @@ BIF_RETTYPE timestamp_0(BIF_ALIST_0)
 
 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);
+    ErtsSystemTime stime = erts_os_system_time();
     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);
+    ErtsSystemTime stime = erts_os_system_time();
     BIF_RET(time_unit_conversion(BIF_P, BIF_ARG_1, stime, 0));
 }
 
diff --git a/erts/emulator/beam/sys.h b/erts/emulator/beam/sys.h
index c51b665db9..27a55e0ec7 100644
--- a/erts/emulator/beam/sys.h
+++ b/erts/emulator/beam/sys.h
@@ -684,7 +684,7 @@ typedef enum {
 } ErtsTimeWarpMode;
 
 typedef struct {
-    int have_os_monotonic;
+    int have_os_monotonic_time;
     ErtsMonotonicTime os_monotonic_time_unit;
     ErtsMonotonicTime sys_clock_resolution;
     struct {
@@ -693,7 +693,13 @@ typedef struct {
 	char *clock_id;
 	int locked_use;
 	int extended;
-    } os_monotonic_info;
+    } os_monotonic_time_info;
+    struct {
+	Uint64 resolution;
+	char *func;
+	char *clock_id;
+	int locked_use;
+    } os_system_time_info;
 } ErtsSysInitTimeResult;
 
 #define ERTS_SYS_INIT_TIME_RESULT_INITER \
diff --git a/erts/emulator/sys/unix/erl_unix_sys.h b/erts/emulator/sys/unix/erl_unix_sys.h
index a14a4b3eae..5394e94c8c 100644
--- a/erts/emulator/sys/unix/erl_unix_sys.h
+++ b/erts/emulator/sys/unix/erl_unix_sys.h
@@ -169,6 +169,10 @@ typedef long long ErtsSysHrTime;
 #error No signed 64-bit type found...
 #endif
 
+typedef ErtsMonotonicTime ErtsSystemTime;
+
+ErtsSystemTime erts_os_system_time(void);
+
 #define ERTS_MONOTONIC_TIME_MIN (((ErtsMonotonicTime) 1) << 63)
 #define ERTS_MONOTONIC_TIME_MAX (~ERTS_MONOTONIC_TIME_MIN)
 
diff --git a/erts/emulator/sys/unix/sys_time.c b/erts/emulator/sys/unix/sys_time.c
index 134e3a67b0..d6591a8296 100644
--- a/erts/emulator/sys/unix/sys_time.c
+++ b/erts/emulator/sys/unix/sys_time.c
@@ -150,44 +150,46 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
 {
 #if !defined(ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT)
 
-    init_resp->have_os_monotonic = 0;
+    init_resp->have_os_monotonic_time = 0;
 
 #else /* defined(ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT) */
 
     int major, minor, build, vsn;
 
-    init_resp->os_monotonic_info.resolution = (Uint64) 1000*1000*1000;
+    init_resp->os_monotonic_time_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;
+	if (clock_getres(MONOTONIC_CLOCK_ID, &ts) == 0) {
+	    if (ts.tv_sec == 0 && ts.tv_nsec != 0)
+		init_resp->os_monotonic_time_info.resolution /= ts.tv_nsec;
+	    else if (ts.tv_sec >= 1)
+		init_resp->os_monotonic_time_info.resolution = 1;
 	}
     }
 #endif
 
 #ifdef MONOTONIC_CLOCK_ID_STR
-    init_resp->os_monotonic_info.clock_id = MONOTONIC_CLOCK_ID_STR;
+    init_resp->os_monotonic_time_info.clock_id = MONOTONIC_CLOCK_ID_STR;
 #else
-    init_resp->os_monotonic_info.clock_id = NULL;
+    init_resp->os_monotonic_time_info.clock_id = NULL;
 #endif
 
-    init_resp->os_monotonic_info.locked_use = 0;
+    init_resp->os_monotonic_time_info.locked_use = 0;
 
 #if defined(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME)
-    init_resp->os_monotonic_info.func = "clock_gettime";
+    init_resp->os_monotonic_time_info.func = "clock_gettime";
 #elif defined(OS_MONOTONIC_TIME_USING_MACH_CLOCK_GET_TIME)
-    init_resp->os_monotonic_info.func = "clock_get_time";
+    init_resp->os_monotonic_time_info.func = "clock_get_time";
 #elif defined(OS_MONOTONIC_TIME_USING_GETHRTIME)
-    init_resp->os_monotonic_info.func = "gethrtime";
+    init_resp->os_monotonic_time_info.func = "gethrtime";
 #elif defined(OS_MONOTONIC_TIME_USING_TIMES)
-    init_resp->os_monotonic_info.func = "times";
+    init_resp->os_monotonic_time_info.func = "times";
 #else
 # error Unknown erts_os_monotonic_time() implementation
 #endif
 
-    init_resp->have_os_monotonic = 1;
+    init_resp->have_os_monotonic_time = 1;
 
     os_version(&major, &minor, &build);
 
@@ -210,7 +212,7 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
 			  "os_monotonic_time");
 	internal_state.w.f.last_delivered
 	    = clock_gettime_monotonic_raw();
-	init_resp->os_monotonic_info.locked_use = 1;
+	init_resp->os_monotonic_time_info.locked_use = 1;
     }
 #else /* !(defined(__linux__) && defined(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME)) */
     {
@@ -227,7 +229,7 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
 #if defined(HAVE_SYSCONF) && defined(_SC_NPROCESSORS_CONF)
 		if (sysconf(_SC_NPROCESSORS_CONF) > 1)
 #endif
-		    init_resp->have_os_monotonic = 0;
+		    init_resp->have_os_monotonic_time = 0;
 	    }
 	}
     }
@@ -261,9 +263,9 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
 	    shift++;
 	}
 
-	init_resp->os_monotonic_info.resolution = resolution;
+	init_resp->os_monotonic_time_info.resolution = resolution;
 	init_resp->os_monotonic_time_unit = time_unit;
-	init_resp->os_monotonic_info.extended = 1;
+	init_resp->os_monotonic_time_info.extended = 1;
 	internal_state.r.o.times_shift = shift;
 
 	erts_init_os_monotonic_time_extender(&internal_state.wr.m.os_mtime_xtnd,
@@ -272,6 +274,38 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
     }
 #endif /* defined(OS_MONOTONIC_TIME_USING_TIMES) */
 
+#ifdef WALL_CLOCK_ID_STR
+    init_resp->os_system_time_info.clock_id = WALL_CLOCK_ID_STR;
+#else
+    init_resp->os_system_time_info.clock_id = NULL;
+#endif
+
+    init_resp->os_system_time_info.locked_use = 0;
+    init_resp->os_system_time_info.resolution = (Uint64) 1000*1000*1000;
+#if defined(HAVE_CLOCK_GETRES) && defined(WALL_CLOCK_ID)
+    {
+	struct timespec ts;
+	if (clock_getres(WALL_CLOCK_ID, &ts) == 0) {
+	    if (ts.tv_sec == 0 && ts.tv_nsec != 0)
+		init_resp->os_system_time_info.resolution /= ts.tv_nsec;
+	    else if (ts.tv_sec >= 1)
+		init_resp->os_system_time_info.resolution = 1;
+	}
+    }
+#endif
+
+#if defined(OS_SYSTEM_TIME_USING_CLOCK_GETTIME)
+    init_resp->os_system_time_info.func = "clock_gettime";
+#elif defined(OS_SYSTEM_TIME_USING_MACH_CLOCK_GET_TIME)
+    init_resp->os_system_time_info.func = "clock_get_time";
+#elif defined(OS_SYSTEM_TIME_GETTIMEOFDAY)
+    init_resp->os_system_time_info.func = "gettimeofday";    
+    init_resp->os_system_time_info.resolution = 1000*1000;
+    init_resp->os_system_time_info.clock_id = NULL;
+#else
+#  error Missing erts_os_system_time() implmenentation
+#endif
+
 }
 
 void
@@ -282,6 +316,105 @@ erts_late_sys_init_time(void)
 #endif
 }
 
+static ERTS_INLINE ErtsSystemTime
+adj_stime_time_unit(ErtsSystemTime stime, Uint32 res)
+{
+    if (res == ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT)
+	return stime;
+    if (res == (Uint32) 1000*1000*1000
+	&& ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT == 1000*1000)
+	return stime/1000;
+    if (res == (Uint32) 1000*1000
+	&& ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT == 1000*1000*1000)
+	return stime*1000;
+    return ((ErtsSystemTime)
+	    erts_time_unit_conversion(stime,
+				      (Uint32) res,
+				      (Uint32) ERTS_MONOTONIC_TIME_UNIT));
+}
+
+#if defined(OS_SYSTEM_TIME_USING_CLOCK_GETTIME)
+
+ErtsSystemTime
+erts_os_system_time(void)
+{
+    ErtsSystemTime stime;
+    struct timespec ts;
+
+    if (clock_gettime(WALL_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",
+		 WALL_CLOCK_ID_STR, errstr, err);
+
+    }
+
+    stime = (ErtsSystemTime) ts.tv_sec;
+    stime *= (ErtsSystemTime) 1000*1000*1000;
+    stime += (ErtsSystemTime) ts.tv_nsec;
+    return adj_stime_time_unit(stime, (Uint32) 1000*1000*1000);
+}
+
+#elif defined(OS_SYSTEM_TIME_USING_MACH_CLOCK_GET_TIME)
+
+ErtsSystemTime
+erts_os_system_time(void)
+{
+    ErtsSystemTime stime;
+    kern_return_t res;
+    clock_serv_t clk_srv;
+    mach_timespec_t time_spec;
+    int err;
+
+    host_get_clock_service(mach_host_self(),
+			   WALL_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);
+    }
+
+    stime = (ErtsSystemTime) time_spec.tv_sec;
+    stime *= (ErtsSystemTime) 1000*1000*1000;
+    stime += (ErtsSystemTime) time_spec.tv_nsec;
+
+    return adj_stime_time_unit(stime, (Uint32) 1000*1000*1000);
+}
+
+#elif defined(OS_SYSTEM_TIME_GETTIMEOFDAY)
+
+ErtsSystemTime
+erts_os_system_time(void)
+{
+    ErtsSystemTime stime;
+    struct timeval tv;
+
+    if (gettimeofday(&tv, NULL) != 0) {
+	int err = errno;
+	char *errstr = err ? strerror(err) : "unknown";
+	erl_exit(ERTS_ABORT_EXIT,
+		 "gettimeofday(_, NULL) failed: %s (%d)\n",
+		 errstr, err);
+    }
+
+    stime = (ErtsSystemTime) tv.tv_sec;
+    stime *= (ErtsSystemTime) 1000*1000;
+    stime += (ErtsSystemTime) tv.tv_usec;
+
+    return adj_stime_time_unit(stime, (Uint32) 1000*1000);
+}
+
+#else
+#  error Missing erts_os_system_time() implmenentation
+#endif
+
 #if defined(OS_MONOTONIC_TIME_USING_CLOCK_GETTIME)
 
 static ERTS_INLINE ErtsMonotonicTime
diff --git a/erts/emulator/sys/win32/erl_win_sys.h b/erts/emulator/sys/win32/erl_win_sys.h
index febf3b5cca..d214ba002c 100644
--- a/erts/emulator/sys/win32/erl_win_sys.h
+++ b/erts/emulator/sys/win32/erl_win_sys.h
@@ -181,6 +181,10 @@ typedef LONGLONG ErtsMonotonicTime;
 typedef LONGLONG ErtsSysHrTime;
 #endif
 
+typedef ErtsMonotonicTime ErtsSystemTime;
+
+ErtsSystemTime erts_os_system_time(void);
+
 #define ERTS_MONOTONIC_TIME_MIN (((ErtsMonotonicTime) 1) << 63)
 #define ERTS_MONOTONIC_TIME_MAX (~ERTS_MONOTONIC_TIME_MIN)
 
diff --git a/erts/emulator/sys/win32/sys_time.c b/erts/emulator/sys/win32/sys_time.c
index ea180f067f..da9c4d2e29 100644
--- a/erts/emulator/sys/win32/sys_time.c
+++ b/erts/emulator/sys/win32/sys_time.c
@@ -73,6 +73,8 @@ 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}};
 
+#define ERTS_GET_TICK_COUNT_TIME_UNIT_SHIFT 10
+
 /*
  * erts_os_monotonic_time()
  */
@@ -81,6 +83,7 @@ struct sys_time_internal_state_read_only__ {
     ULONGLONG (WINAPI *pGetTickCount64)(void);
     BOOL (WINAPI *pQueryPerformanceCounter)(LARGE_INTEGER *);
     Sint32 pcf;
+    int using_get_tick_count_time_unit;
 };
 
 struct sys_time_internal_state_read_mostly__ {
@@ -199,7 +202,7 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
     char kernel_dll_name[] = "kernel32";
     HMODULE module;
 
-    init_resp->os_monotonic_info.clock_id = NULL;
+    init_resp->os_monotonic_time_info.clock_id = NULL;
 
     module = GetModuleHandle(kernel_dll_name);
     if (!module) {
@@ -209,13 +212,15 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
 	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_time_info.func = "GetTickCount";
+	init_resp->os_monotonic_time_info.locked_use = 1;
 	/* 10-16 ms resolution according to MicroSoft documentation */
-	init_resp->os_monotonic_info.resolution = 100; /* 10 ms */
-	time_unit = (ErtsMonotonicTime) (1000 << 10);
+	init_resp->os_monotonic_time_info.resolution = 100; /* 10 ms */
+	time_unit = (ErtsMonotonicTime) 1000;
+	time_unit <<= ERTS_GET_TICK_COUNT_TIME_UNIT_SHIFT;
+	internal_state.r.o.using_get_tick_count_time_unit = 1;
 	os_mtime_func = os_monotonic_time_gtc32;
-	init_resp->os_monotonic_info.extended = 1;
+	init_resp->os_monotonic_time_info.extended = 1;
 	erts_init_os_monotonic_time_extender(&internal_state.wr.m.os_mtime_xtnd,
 					     get_tick_count,
 					     60*60*24*7); /* Check once a week */
@@ -237,11 +242,13 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
 	    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_time_info.func = "GetTickCount64";
+	    init_resp->os_monotonic_time_info.locked_use = 0;
 	    /* 10-16 ms resolution according to MicroSoft documentation */
-	    init_resp->os_monotonic_info.resolution = 100; /* 10 ms */
-	    time_unit = (ErtsMonotonicTime) (1000 << 10);
+	    init_resp->os_monotonic_time_info.resolution = 100; /* 10 ms */
+	    time_unit = (ErtsMonotonicTime) 1000;
+	    time_unit <<= ERTS_GET_TICK_COUNT_TIME_UNIT_SHIFT;
+	    internal_state.r.o.using_get_tick_count_time_unit = 1;
 	    os_mtime_func = os_monotonic_time_gtc64;
 	    if (!sys_hrtime_func)
 		sys_hrtime_func = sys_hrtime_gtc64;
@@ -279,25 +286,30 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
 	    if (pf.QuadPart < (LONGLONG) 1000*1000*1000)
 		goto get_tick_count64;
 
-	    init_resp->os_monotonic_info.func = "QueryPerformanceCounter";
-	    init_resp->os_monotonic_info.locked_use = 0;
+	    init_resp->os_monotonic_time_info.func = "QueryPerformanceCounter";
+	    init_resp->os_monotonic_time_info.locked_use = 0;
 	    time_unit = (ErtsMonotonicTime) pf.QuadPart;
-	    init_resp->os_monotonic_info.resolution = time_unit;
+	    internal_state.r.o.using_get_tick_count_time_unit = 0;
+	    init_resp->os_monotonic_time_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->have_os_monotonic_time = 1;
     init_resp->sys_clock_resolution = 1;
 
+    init_resp->os_system_time_info.func = "GetSystemTime";    
+    init_resp->os_system_time_info.clock_id = NULL;
+    init_resp->os_system_time_info.resolution = 100;
+    init_resp->os_system_time_info.locked_use = 0;
+
     if(GetTimeZoneInformation(&static_tzi) && 
        static_tzi.StandardDate.wMonth != 0 &&
        static_tzi.DaylightDate.wMonth != 0) {
 	have_static_tzi = 1;
     }
-
 }
 
 void
@@ -585,6 +597,37 @@ sys_gettimeofday(SysTimeval *tv)
 			 EPOCH_JULIAN_DIFF);
 }
 
+ErtsSystemTime
+erts_os_system_time(void)
+{
+    SYSTEMTIME t;
+    FILETIME ft;
+    ULARGE_INTEGER ull;
+    ErtsSystemTime stime;
+
+    GetSystemTime(&t);
+    SystemTimeToFileTime(&t, &ft);
+    FILETIME_TO_ULI(ull,ft);
+
+    /* now in 100 ns units */
+
+    stime = (ErtsSystemTime) ull.QuadPart;
+    stime -= (((ErtsSystemTime) EPOCH_JULIAN_DIFF)
+	      * ((ErtsSystemTime) (10*1000*1000)));
+    stime /= (ErtsSystemTime) (10*1000);
+
+    if (internal_state.r.o.using_get_tick_count_time_unit) {
+	stime <<= ERTS_GET_TICK_COUNT_TIME_UNIT_SHIFT;
+	return stime;
+    }
+
+    return ((ErtsSystemTime)
+	    erts_time_unit_conversion(stime,
+				      (Uint32) 1000,
+				      (Uint32) ERTS_MONOTONIC_TIME_UNIT));
+}
+
+
 clock_t 
 sys_times(SysTimes *buffer) {
     clock_t kernel_ticks = (GetTickCount() /