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PEP 418: Patch bench_time.c to support systems without clock_gettime()

This commit is contained in:
Victor Stinner 2012-04-19 23:26:51 +02:00
parent a0e363488b
commit bfcd81b80e
1 changed files with 37 additions and 10 deletions
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47
pep-0418/bench_time.c
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@ -8,12 +8,20 @@
#include <stdio.h>
#include <sys/time.h>
#ifdef CLOCK_REALTIME
# define HAVE_CLOCK_GETTIME
#else
typedef int clockid_t;
#endif
#define NRUN 5
#define NLOOP 1000000
#define NLOOP 100000
#define UNROLL(expr) \
expr; expr; expr; expr; expr; expr; expr; expr; expr; expr
#define NUNROLL 10
#ifdef HAVE_CLOCK_GETTIME
typedef struct {
const char *name;
clockid_t identifier;
@ -80,6 +88,8 @@ void bench_clock_gettime(clockid_t clkid)
}
}
#endif /* HAVE_CLOCK_GETTIME */
void bench_time(clockid_t clkid)
{
unsigned long loop;
@ -117,25 +127,40 @@ void benchmark(const char *name, void (*func) (clockid_t clkid), clockid_t clkid
{
unsigned int run;
double dt, best;
struct timespec before, after, tmpspec;
#ifdef HAVE_CLOCK_GETTIME
struct timespec before, after;
#else
struct timeval before, after;
#endif
struct timeval tmpval;
best = 0;
best = -1.0;
for (run=0; run<NRUN; run++) {
#ifdef HAVE_CLOCK_GETTIME
clock_gettime(CLOCK_MONOTONIC, &before);
(*func) (clkid);
clock_gettime(CLOCK_MONOTONIC, &after);
dt = after.tv_sec - before.tv_sec;
dt = (after.tv_sec - before.tv_sec) * 1e9;
if (after.tv_nsec >= before.tv_nsec)
dt += (after.tv_nsec - before.tv_nsec) * 1e-9;
dt += (after.tv_nsec - before.tv_nsec);
else
{
dt -= (before.tv_nsec - after.tv_nsec) * 1e-9;
}
dt *= (double)1e9 / NLOOP / NUNROLL;
dt -= (before.tv_nsec - after.tv_nsec);
#else
gettimeofday(&before, NULL);
(*func) (clkid);
gettimeofday(&after, NULL);
if (best != 0.0) {
dt = (after.tv_sec - before.tv_sec) * 1e9;
if (after.tv_usec >= before.tv_usec)
dt += (after.tv_usec - before.tv_usec) * 1e3;
else
dt -= (before.tv_usec - after.tv_usec) * 1e3;
#endif
dt /= NLOOP;
dt /= NUNROLL;
if (best != -1.0) {
if (dt < best)
best = dt;
}
@ -147,12 +172,14 @@ void benchmark(const char *name, void (*func) (clockid_t clkid), clockid_t clkid
int main()
{
#ifdef HAVE_CLOCK_GETTIME
clockid_t clkid;
int i;
for (i=0; i<NCLOCKS; i++) {
benchmark(clocks[i].name, bench_clock_gettime, clocks[i].identifier);
}
#endif
benchmark("clock()", bench_clock, 0);
benchmark("gettimeofday()", bench_gettimeofday, 0);
benchmark("time()", bench_time, 0);