diff options
Diffstat (limited to 'erts/emulator/sys/unix')
| -rw-r--r-- | erts/emulator/sys/unix/erl_unix_sys.h | 27 | ||||
| -rw-r--r-- | erts/emulator/sys/unix/sys_time.c | 114 |
2 files changed, 140 insertions, 1 deletions
diff --git a/erts/emulator/sys/unix/erl_unix_sys.h b/erts/emulator/sys/unix/erl_unix_sys.h index 0352ee1b3c..8b1822ca9f 100644 --- a/erts/emulator/sys/unix/erl_unix_sys.h +++ b/erts/emulator/sys/unix/erl_unix_sys.h @@ -101,6 +101,10 @@ #endif #include <netdb.h> +#ifdef HAVE_MACH_ABSOLUTE_TIME +#include <mach/mach_time.h> +#endif + #ifdef HAVE_POSIX_MEMALIGN # define ERTS_HAVE_ERTS_SYS_ALIGNED_ALLOC 1 #endif @@ -157,6 +161,7 @@ typedef long long ErtsSysHrTime; #endif typedef ErtsMonotonicTime ErtsSystemTime; +typedef ErtsSysHrTime ErtsSysPerfCounter; #define ERTS_MONOTONIC_TIME_MIN (((ErtsMonotonicTime) 1) << 63) #define ERTS_MONOTONIC_TIME_MAX (~ERTS_MONOTONIC_TIME_MIN) @@ -205,6 +210,7 @@ ErtsSystemTime erts_os_system_time(void); * It may or may not be monotonic. */ ErtsSysHrTime erts_sys_hrtime(void); +#define ERTS_HRTIME_UNIT (1000*1000*1000) struct erts_sys_time_read_only_data__ { #ifdef ERTS_OS_MONOTONIC_INLINE_FUNC_PTR_CALL__ @@ -213,6 +219,8 @@ struct erts_sys_time_read_only_data__ { #ifdef ERTS_OS_TIMES_INLINE_FUNC_PTR_CALL__ void (*os_times)(ErtsMonotonicTime *, ErtsSystemTime *); #endif + ErtsSysPerfCounter (*perf_counter)(void); + ErtsSysPerfCounter perf_counter_unit; int ticks_per_sec; }; @@ -266,7 +274,24 @@ erts_os_times(ErtsMonotonicTime *mtimep, ErtsSystemTime *stimep) #endif /* ERTS_HAVE_OS_MONOTONIC_TIME_SUPPORT */ /* - * + * Functions for getting the performance counter + */ + +ERTS_GLB_INLINE ErtsSysPerfCounter erts_sys_perf_counter(void); +#define erts_sys_perf_counter_unit() erts_sys_time_data__.r.o.perf_counter_unit + +#if ERTS_GLB_INLINE_INCL_FUNC_DEF + +ERTS_GLB_INLINE ErtsSysPerfCounter +erts_sys_perf_counter() +{ + return (*erts_sys_time_data__.r.o.perf_counter)(); +} + +#endif /* ERTS_GLB_INLINE_INCL_FUNC_DEF */ + +/* + * Functions for measuring CPU time */ #if (defined(HAVE_GETHRVTIME) || defined(HAVE_CLOCK_GETTIME_CPU_TIME)) diff --git a/erts/emulator/sys/unix/sys_time.c b/erts/emulator/sys/unix/sys_time.c index 2e1914f564..03d39c7ce6 100644 --- a/erts/emulator/sys/unix/sys_time.c +++ b/erts/emulator/sys/unix/sys_time.c @@ -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__ @@ -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; |