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Diffstat (limited to 'erts/emulator/sys/unix/sys_time.c')
-rw-r--r--erts/emulator/sys/unix/sys_time.c132
1 files changed, 123 insertions, 9 deletions
diff --git a/erts/emulator/sys/unix/sys_time.c b/erts/emulator/sys/unix/sys_time.c
index 95b3daa4ed..4f26639703 100644
--- a/erts/emulator/sys/unix/sys_time.c
+++ b/erts/emulator/sys/unix/sys_time.c
@@ -1,7 +1,7 @@
/*
* %CopyrightBegin%
*
- * Copyright Ericsson AB 2005-2009. All Rights Reserved.
+ * Copyright Ericsson AB 2005-2016. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -65,6 +65,8 @@
# include <fcntl.h>
#endif
+static void init_perf_counter(void);
+
/******************* Routines for time measurement *********************/
#undef ERTS_SYS_TIME_INTERNAL_STATE_WRITE_FREQ__
@@ -217,7 +219,10 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
#endif
init_resp->os_monotonic_time_info.resolution = (Uint64) 1000*1000*1000;
-#if defined(HAVE_CLOCK_GETRES) && defined(MONOTONIC_CLOCK_ID)
+#if defined(ERTS_HAVE_MACH_CLOCK_GETRES) && defined(MONOTONIC_CLOCK_ID)
+ init_resp->os_monotonic_time_info.resolution
+ = mach_clock_getres(&internal_state.r.o.mach.clock.monotonic);
+#elif defined(HAVE_CLOCK_GETRES) && defined(MONOTONIC_CLOCK_ID)
{
struct timespec ts;
if (clock_getres(MONOTONIC_CLOCK_ID, &ts) == 0) {
@@ -227,9 +232,6 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
init_resp->os_monotonic_time_info.resolution = 1;
}
}
-#elif defined(ERTS_HAVE_MACH_CLOCK_GETRES) && defined(MONOTONIC_CLOCK_ID)
- init_resp->os_monotonic_time_info.resolution
- = mach_clock_getres(&internal_state.r.o.mach.clock.monotonic);
#endif
#ifdef MONOTONIC_CLOCK_ID_STR
@@ -377,7 +379,10 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
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)
+#if defined(ERTS_HAVE_MACH_CLOCK_GETRES) && defined(WALL_CLOCK_ID)
+ init_resp->os_system_time_info.resolution
+ = mach_clock_getres(&internal_state.r.o.mach.clock.wall);
+#elif defined(HAVE_CLOCK_GETRES) && defined(WALL_CLOCK_ID)
{
struct timespec ts;
if (clock_getres(WALL_CLOCK_ID, &ts) == 0) {
@@ -387,9 +392,6 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
init_resp->os_system_time_info.resolution = 1;
}
}
-#elif defined(ERTS_HAVE_MACH_CLOCK_GETRES) && defined(WALL_CLOCK_ID)
- init_resp->os_system_time_info.resolution
- = mach_clock_getres(&internal_state.r.o.mach.clock.wall);
#endif
#if defined(OS_SYSTEM_TIME_USING_CLOCK_GETTIME)
@@ -404,6 +406,8 @@ sys_init_time(ErtsSysInitTimeResult *init_resp)
# error Missing erts_os_system_time() implementation
#endif
+ init_perf_counter();
+
}
void
@@ -908,10 +912,120 @@ erts_os_times(ErtsMonotonicTime *mtimep, ErtsSystemTime *stimep)
#endif
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *\
+ * Performance counter functions *
+\* */
+
+
+/* What resolution to spin to in micro seconds */
+#define RESOLUTION 100
+/* How many iterations to spin */
+#define ITERATIONS 1
+/* How many significant figures to round to */
+#define SIGFIGS 3
+
+static ErtsSysPerfCounter calculate_perf_counter_unit(void) {
+ int i;
+ ErtsSysPerfCounter pre, post;
+ double value = 0;
+ double round_factor;
+#if defined(HAVE_GETHRTIME) && defined(GETHRTIME_WITH_CLOCK_GETTIME)
+ struct timespec basetime,comparetime;
+#define __GETTIME(arg) clock_gettime(CLOCK_MONOTONIC,arg)
+#define __GETUSEC(arg) (arg.tv_nsec / 1000)
+#else
+ SysTimeval basetime,comparetime;
+#define __GETTIME(arg) sys_gettimeofday(arg)
+#define __GETUSEC(arg) arg.tv_usec
+#endif
+
+ for (i = 0; i < ITERATIONS; i++) {
+ /* Make sure usec just flipped over at current resolution */
+ __GETTIME(&basetime);
+ do {
+ __GETTIME(&comparetime);
+ } while ((__GETUSEC(basetime) / RESOLUTION) == (__GETUSEC(comparetime) / RESOLUTION));
+
+ pre = erts_sys_perf_counter();
+
+ __GETTIME(&basetime);
+ do {
+ __GETTIME(&comparetime);
+ } while ((__GETUSEC(basetime) / RESOLUTION) == (__GETUSEC(comparetime) / RESOLUTION));
+
+ post = erts_sys_perf_counter();
+
+ value += post - pre;
+ }
+ /* After this value is ticks per us */
+ value /= (RESOLUTION*ITERATIONS);
+
+ /* We round to 3 significant figures */
+ round_factor = pow(10.0, SIGFIGS - ceil(log10(value)));
+ value = ((ErtsSysPerfCounter)(value * round_factor + 0.5)) / round_factor;
+
+ /* convert to ticks per second */
+ return 1000000 * value;
+}
+
+static int have_rdtscp(void)
+{
+#if defined(ETHR_X86_RUNTIME_CONF__)
+ /* On early x86 cpu's the tsc varies with the current speed of the cpu,
+ which means that the time per tick vary depending on the current
+ load of the cpu. We do not want this as it would give very scewed
+ numbers when the cpu is mostly idle.
+ The linux kernel seems to think that checking for constant and
+ reliable is enough to trust the counter so we do the same.
+
+ If this test is not good enough, I don't know what we'll do.
+ Maybe fallback on erts_sys_hrtime always, but that would be a shame as
+ rdtsc is about 3 times faster than hrtime... */
+ return ETHR_X86_RUNTIME_CONF_HAVE_CONSTANT_TSC__ &&
+ ETHR_X86_RUNTIME_CONF_HAVE_TSC_RELIABLE__;
+#else
+ return 0;
+#endif
+}
+
+static ErtsSysPerfCounter rdtsc(void)
+{
+ /* It may have been a good idea to put the cpuid instruction before
+ the rdtsc, but I decided against it because it is not really
+ needed for msacc, and it slows it down by quite a bit (5-7 times slower).
+ As a result though, this timestamp becomes much less
+ accurate as it might be re-ordered to be executed way before or after this
+ function is called.
+ */
+ ErtsSysPerfCounter ts;
+#if defined(__x86_64__)
+ __asm__ __volatile__ ("rdtsc\n\t"
+ "shl $32, %%rdx\n\t"
+ "or %%rdx, %0" : "=a" (ts) : : "rdx");
+#elif defined(__i386__)
+ __asm__ __volatile__ ("rdtsc\n\t"
+ : "=A" (ts) );
+#endif
+ return ts;
+}
+
+static void init_perf_counter(void)
+{
+ if (have_rdtscp()) {
+ erts_sys_time_data__.r.o.perf_counter = rdtsc;
+ erts_sys_time_data__.r.o.perf_counter_unit = calculate_perf_counter_unit();
+ } else {
+ erts_sys_time_data__.r.o.perf_counter = erts_sys_hrtime;
+ erts_sys_time_data__.r.o.perf_counter_unit = ERTS_HRTIME_UNIT;
+ }
+}
+
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
#ifdef HAVE_GETHRVTIME_PROCFS_IOCTL
+/* The code below only has effect on solaris < 10,
+ needed in order for gehhrvtime to work properly */
int sys_start_hrvtime(void)
{
long msacct = PR_MSACCT;
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