diff options
Diffstat (limited to 'src/bin')
| -rw-r--r-- | src/bin/pg_test_timing/pg_test_timing.c | 18 |
1 files changed, 14 insertions, 4 deletions
diff --git a/src/bin/pg_test_timing/pg_test_timing.c b/src/bin/pg_test_timing/pg_test_timing.c index 64d080335eb..a5621251afc 100644 --- a/src/bin/pg_test_timing/pg_test_timing.c +++ b/src/bin/pg_test_timing/pg_test_timing.c @@ -20,8 +20,8 @@ static double max_rprct = 99.99; /* record duration in powers of 2 nanoseconds */ static long long int histogram[32]; -/* record counts of first 1024 durations directly */ -#define NUM_DIRECT 1024 +/* record counts of first 10K durations directly */ +#define NUM_DIRECT 10000 static long long int direct_histogram[NUM_DIRECT]; /* separately record highest observed duration */ @@ -161,6 +161,16 @@ test_timing(unsigned int duration) end_time, temp; + /* + * Pre-zero the statistics data structures. They're already zero by + * default, but this helps bring them into processor cache and avoid + * possible timing glitches due to COW behavior. + */ + memset(direct_histogram, 0, sizeof(direct_histogram)); + memset(histogram, 0, sizeof(histogram)); + largest_diff = 0; + largest_diff_count = 0; + total_time = duration > 0 ? duration * INT64CONST(1000000000) : 0; INSTR_TIME_SET_CURRENT(start_time); @@ -177,7 +187,7 @@ test_timing(unsigned int duration) diff = cur - prev; /* Did time go backwards? */ - if (diff < 0) + if (unlikely(diff < 0)) { fprintf(stderr, _("Detected clock going backwards in time.\n")); fprintf(stderr, _("Time warp: %d ms\n"), diff); @@ -215,7 +225,7 @@ test_timing(unsigned int duration) INSTR_TIME_SUBTRACT(end_time, start_time); - printf(_("Per loop time including overhead: %0.2f ns\n"), + printf(_("Average loop time including overhead: %0.2f ns\n"), INSTR_TIME_GET_DOUBLE(end_time) * 1e9 / loop_count); return loop_count; |