[Python-checkins] peps: PEP 418: Patch bench_time.c to support systems without clock_gettime()

Thu Apr 19 23:26:53 CEST 2012

http://hg.python.org/peps/rev/0705221c05c3
changeset: 4279:0705221c05c3
user: Victor Stinner <victor.stinner at gmail.com>
date: Thu Apr 19 23:26:51 2012 +0200
summary:
 PEP 418: Patch bench_time.c to support systems without clock_gettime()
files:
 pep-0418/bench_time.c | 47 ++++++++++++++++++++++++------
 1 files changed, 37 insertions(+), 10 deletions(-)

diff --git a/pep-0418/bench_time.c b/pep-0418/bench_time.c
--- a/pep-0418/bench_time.c
+++ b/pep-0418/bench_time.c
@@ -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 @@
 }
 }
 
+#endif /* HAVE_CLOCK_GETTIME */
+
 void bench_time(clockid_t clkid)
 {
 unsigned long loop;
@@ -117,25 +127,40 @@
 {
 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 @@
 
 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);
-- 
Repository URL: http://hg.python.org/peps
