Merge branch 'rickard/time_api/OTP-11997'

* rickard/time_api/OTP-11997:
  Better OS system time implementation
  Documentation adjustments
  Fix zero timout timers
  erts_sys_hrtime() for lcnt
  Better support for poor os monotonic sources

Conflicts:
	erts/preloaded/ebin/erlang.beam

1 files changed, 239 insertions, 152 deletions

diff --git a/erts/emulator/sys/unix/sys_time.c b/erts/emulator/sys/unix/sys_time.c
index 9fdb1930b7..d6591a8296 100644
--- a/erts/emulator/sys/unix/sys_time.c
+++ b/erts/emulator/sys/unix/sys_time.c
@@ -33,6 +33,7 @@
 
 #include "sys.h"
 #include "global.h"
+#include "erl_os_monotonic_time_extender.h"
 
 #ifdef NO_SYSCONF
 #  define TICKS_PER_SEC()	HZ
@@ -55,36 +56,19 @@
 
 #undef ERTS_SYS_TIME_INTERNAL_STATE_WRITE_FREQ__
 #undef ERTS_SYS_TIME_INTERNAL_STATE_READ_ONLY__
+#undef ERTS_SYS_TIME_INTERNAL_STATE_READ_MOSTLY__
 
 #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
+static Uint32
+get_tick_count(void)
+{
+    struct tms unused;
+    return (Uint32) times(&unused);
+}
 
-#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
+#define ERTS_SYS_TIME_INTERNAL_STATE_READ_ONLY__
+#define ERTS_SYS_TIME_INTERNAL_STATE_READ_MOSTLY__
 
 #endif
 
@@ -101,16 +85,23 @@ ErtsSysTimeData__ erts_sys_time_data__ erts_align_attribute(ERTS_CACHE_LINE_SIZE
 
 #define ERTS_SYS_TIME_INTERNAL_STATE_WRITE_FREQ__
 
-ErtsMonotonicTime clock_gettime_monotonic_raw(void);
-ErtsMonotonicTime clock_gettime_monotonic_verified(void);
+static ErtsMonotonicTime clock_gettime_monotonic_raw(void);
+static 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;
+    int times_shift;
+#endif
+};
+#endif
+
+#ifdef ERTS_SYS_TIME_INTERNAL_STATE_READ_MOSTLY__
+struct sys_time_internal_state_read_mostly__ {
+#if defined(OS_MONOTONIC_TIME_USING_TIMES)
+    ErtsOsMonotonicTimeExtendState os_mtime_xtnd;
 #endif
 };
 #endif
@@ -121,15 +112,6 @@ struct sys_time_internal_state_write_freq__ {
 #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
 
@@ -144,6 +126,14 @@ static struct {
 		     * ASSUMED_CACHE_LINE_SIZE];
     } r;
 #endif
+#ifdef ERTS_SYS_TIME_INTERNAL_STATE_READ_MOSTLY__
+    union {
+	struct sys_time_internal_state_read_mostly__ m;
+	char align__[(((sizeof(struct sys_time_internal_state_read_mostly__) - 1)
+		       / ASSUMED_CACHE_LINE_SIZE) + 1)
+		     * ASSUMED_CACHE_LINE_SIZE];
+    } wr;
+#endif
 #ifdef ERTS_SYS_TIME_INTERNAL_STATE_WRITE_FREQ__
     union {
 	struct sys_time_internal_state_write_freq__ f;
@@ -160,46 +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_info.locked_use = 1;
-    init_resp->os_monotonic_info.resolution = TICKS_PER_SEC();
+    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);
 
@@ -222,7 +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)) */
     {
@@ -239,7 +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;
 	    }
 	}
     }
@@ -247,7 +237,9 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
 
 #endif /* defined(ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT) */
 
+#ifdef ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT
     init_resp->os_monotonic_time_unit = ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT;
+#endif
     init_resp->sys_clock_resolution = SYS_CLOCK_RESOLUTION;
 
     /* 
@@ -258,38 +250,171 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
 	erl_exit(ERTS_ABORT_EXIT, "Can't get clock ticks/sec\n");
     
 #if defined(OS_MONOTONIC_TIME_USING_TIMES)
+#if ERTS_COMPILE_TIME_MONOTONIC_TIME_UNIT
+#  error Time unit is supposed to be determined at runtime...
+#endif
+    {
+	ErtsMonotonicTime resolution = erts_sys_time_data__.r.o.ticks_per_sec;
+	ErtsMonotonicTime time_unit = resolution;
+	int shift = 0;
 
-    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 */
-	internal_state.r.o.ticks_bsr = 3;
-    } else {
-	internal_state.r.o.ticks_bsr = 0;
+	while (time_unit < 1000*1000) {
+	    time_unit <<= 1;
+	    shift++;
+	}
+
+	init_resp->os_monotonic_time_info.resolution = resolution;
+	init_resp->os_monotonic_time_unit = time_unit;
+	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,
+					     get_tick_count,
+					     (1 << 29) / resolution);
     }
+#endif /* defined(OS_MONOTONIC_TIME_USING_TIMES) */
 
-    internal_state.r.o.ticks_per_sec_wrap
-	= (erts_sys_time_data__.r.o.ticks_per_sec
-	   >> internal_state.r.o.ticks_bsr);
+#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
 
-    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);
+    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)
     {
-	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;
+	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
 
-#endif /* defined(OS_MONOTONIC_TIME_USING_TIMES) */
+#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
+erts_late_sys_init_time(void)
+{
+#if defined(OS_MONOTONIC_TIME_USING_TIMES)
+    erts_late_init_os_monotonic_time_extender(&internal_state.wr.m.os_mtime_xtnd);
+#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
@@ -314,7 +439,7 @@ clock_gettime_monotonic(void)
 
 #if defined(__linux__)
 
-ErtsMonotonicTime clock_gettime_monotonic_verified(void)
+static ErtsMonotonicTime clock_gettime_monotonic_verified(void)
 {
     ErtsMonotonicTime mtime;
 
@@ -330,7 +455,7 @@ ErtsMonotonicTime clock_gettime_monotonic_verified(void)
     return mtime;
 }
 
-ErtsMonotonicTime clock_gettime_monotonic_raw(void)
+static ErtsMonotonicTime clock_gettime_monotonic_raw(void)
 {
     return clock_gettime_monotonic();
 }
@@ -344,6 +469,12 @@ ErtsMonotonicTime erts_os_monotonic_time(void)
 
 #endif /* !defined(__linux__) */
 
+ErtsSysHrTime
+erts_sys_hrtime(void)
+{
+    return (ErtsSysHrTime) clock_gettime_monotonic();
+}
+
 #elif defined(OS_MONOTONIC_TIME_USING_MACH_CLOCK_GET_TIME)
 
 #include <mach/clock.h>
@@ -377,91 +508,47 @@ ErtsMonotonicTime erts_os_monotonic_time(void)
     return mtime;
 }
 
-#elif defined(OS_MONOTONIC_TIME_USING_TIMES)
-
-static clock_t sys_times_wrap(void)
-{
-    SysTimes dummy;
-    clock_t result = (sys_times(&dummy) >> internal_state.r.o.ticks_bsr);
-    return result;
-}
-
-void
-erts_os_time_offset_finalize(void)
+ErtsSysHrTime
+erts_sys_hrtime(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);
+    return (ErtsSysHrTime) erts_os_monotonic_time();
 }
 
-#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))
+#elif defined(OS_MONOTONIC_TIME_USING_TIMES)
 
-/* 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;
-	}
-    }
+    Uint32 ticks = get_tick_count();
+    ERTS_CHK_EXTEND_OS_MONOTONIC_TIME(&internal_state.wr.m.os_mtime_xtnd,
+				      ticks);
+    return ERTS_EXTEND_OS_MONOTONIC_TIME(&internal_state.wr.m.os_mtime_xtnd,
+					 ticks) << internal_state.r.o.times_shift;
+}
 
-    if (internal_state.w.f.last_tick_monotonic_time < tick_monotonic_time)
-	internal_state.w.f.last_tick_monotonic_time = tick_monotonic_time;
+#  define ERTS_NEED_ERTS_SYS_HRTIME_FALLBACK
 
-    res = internal_state.w.f.last_tick_monotonic_time;
+#else  /* !defined(OS_MONOTONIC_TIME_USING_TIMES) */
+/* No os-monotonic-time */
+#  define ERTS_NEED_ERTS_SYS_HRTIME_FALLBACK
+#endif
 
-    erts_smp_mtx_unlock(&internal_state.w.f.mtx);
+#ifdef ERTS_NEED_ERTS_SYS_HRTIME_FALLBACK
 
-    return res;
+ErtsSysHrTime
+erts_sys_hrtime(void)
+{
+    ErtsSysHrTime time;
+    struct timeval tv;
+    gettimeofday(&tv);
+    time = (ErtsSysHrTime) tv.tv_sec;
+    time *= (ErtsSysHrTime) 1000*1000*1000;
+    time += ((ErtsSysHrTime) tv.tv_usec)*1000;
+    return time;
 }
 
-#endif  /* !defined(OS_MONOTONIC_TIME_USING_TIMES) */
+#endif
+
 
 #ifdef HAVE_GETHRVTIME_PROCFS_IOCTL