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Diffstat (limited to 'src/bin/pg_test_timing/pg_test_timing.c')
-rw-r--r--src/bin/pg_test_timing/pg_test_timing.c186
1 files changed, 153 insertions, 33 deletions
diff --git a/src/bin/pg_test_timing/pg_test_timing.c b/src/bin/pg_test_timing/pg_test_timing.c
index ce7aad4b25a..a5621251afc 100644
--- a/src/bin/pg_test_timing/pg_test_timing.c
+++ b/src/bin/pg_test_timing/pg_test_timing.c
@@ -9,19 +9,30 @@
#include <limits.h>
#include "getopt_long.h"
+#include "port/pg_bitutils.h"
#include "portability/instr_time.h"
static const char *progname;
static unsigned int test_duration = 3;
+static double max_rprct = 99.99;
+
+/* record duration in powers of 2 nanoseconds */
+static long long int histogram[32];
+
+/* record counts of first 10K durations directly */
+#define NUM_DIRECT 10000
+static long long int direct_histogram[NUM_DIRECT];
+
+/* separately record highest observed duration */
+static int32 largest_diff;
+static long long int largest_diff_count;
+
static void handle_args(int argc, char *argv[]);
static uint64 test_timing(unsigned int duration);
static void output(uint64 loop_count);
-/* record duration in powers of 2 microseconds */
-static long long int histogram[32];
-
int
main(int argc, char *argv[])
{
@@ -44,6 +55,7 @@ handle_args(int argc, char *argv[])
{
static struct option long_options[] = {
{"duration", required_argument, NULL, 'd'},
+ {"cutoff", required_argument, NULL, 'c'},
{NULL, 0, NULL, 0}
};
@@ -56,7 +68,7 @@ handle_args(int argc, char *argv[])
{
if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
{
- printf(_("Usage: %s [-d DURATION]\n"), progname);
+ printf(_("Usage: %s [-d DURATION] [-c CUTOFF]\n"), progname);
exit(0);
}
if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)
@@ -66,7 +78,7 @@ handle_args(int argc, char *argv[])
}
}
- while ((option = getopt_long(argc, argv, "d:",
+ while ((option = getopt_long(argc, argv, "d:c:",
long_options, &optindex)) != -1)
{
switch (option)
@@ -93,6 +105,26 @@ handle_args(int argc, char *argv[])
}
break;
+ case 'c':
+ errno = 0;
+ max_rprct = strtod(optarg, &endptr);
+
+ if (endptr == optarg || *endptr != '\0' || errno != 0)
+ {
+ fprintf(stderr, _("%s: invalid argument for option %s\n"),
+ progname, "--cutoff");
+ fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
+ exit(1);
+ }
+
+ if (max_rprct < 0 || max_rprct > 100)
+ {
+ fprintf(stderr, _("%s: %s must be in range %u..%u\n"),
+ progname, "--cutoff", 0, 100);
+ exit(1);
+ }
+ break;
+
default:
fprintf(stderr, _("Try \"%s --help\" for more information.\n"),
progname);
@@ -111,7 +143,6 @@ handle_args(int argc, char *argv[])
exit(1);
}
-
printf(ngettext("Testing timing overhead for %u second.\n",
"Testing timing overhead for %u seconds.\n",
test_duration),
@@ -130,23 +161,33 @@ test_timing(unsigned int duration)
end_time,
temp;
- total_time = duration > 0 ? duration * INT64CONST(1000000) : 0;
+ /*
+ * 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);
- cur = INSTR_TIME_GET_MICROSEC(start_time);
+ cur = INSTR_TIME_GET_NANOSEC(start_time);
while (time_elapsed < total_time)
{
int32 diff,
- bits = 0;
+ bits;
prev = cur;
INSTR_TIME_SET_CURRENT(temp);
- cur = INSTR_TIME_GET_MICROSEC(temp);
+ cur = INSTR_TIME_GET_NANOSEC(temp);
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);
@@ -154,25 +195,37 @@ test_timing(unsigned int duration)
}
/* What is the highest bit in the time diff? */
- while (diff)
- {
- diff >>= 1;
- bits++;
- }
+ if (diff > 0)
+ bits = pg_leftmost_one_pos32(diff) + 1;
+ else
+ bits = 0;
/* Update appropriate duration bucket */
histogram[bits]++;
+ /* Update direct histogram of time diffs */
+ if (diff < NUM_DIRECT)
+ direct_histogram[diff]++;
+
+ /* Also track the largest observed duration, even if >= NUM_DIRECT */
+ if (diff > largest_diff)
+ {
+ largest_diff = diff;
+ largest_diff_count = 1;
+ }
+ else if (diff == largest_diff)
+ largest_diff_count++;
+
loop_count++;
INSTR_TIME_SUBTRACT(temp, start_time);
- time_elapsed = INSTR_TIME_GET_MICROSEC(temp);
+ time_elapsed = INSTR_TIME_GET_NANOSEC(temp);
}
INSTR_TIME_SET_CURRENT(end_time);
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;
@@ -181,28 +234,95 @@ test_timing(unsigned int duration)
static void
output(uint64 loop_count)
{
- int64 max_bit = 31,
- i;
- char *header1 = _("< us");
- char *header2 = /* xgettext:no-c-format */ _("% of total");
- char *header3 = _("count");
+ int max_bit = 31;
+ const char *header1 = _("<= ns");
+ const char *header1b = _("ns");
+ const char *header2 = /* xgettext:no-c-format */ _("% of total");
+ const char *header3 = /* xgettext:no-c-format */ _("running %");
+ const char *header4 = _("count");
int len1 = strlen(header1);
int len2 = strlen(header2);
int len3 = strlen(header3);
+ int len4 = strlen(header4);
+ double rprct;
+ bool stopped = false;
/* find highest bit value */
while (max_bit > 0 && histogram[max_bit] == 0)
max_bit--;
+ /* set minimum column widths */
+ len1 = Max(8, len1);
+ len2 = Max(10, len2);
+ len3 = Max(10, len3);
+ len4 = Max(10, len4);
+
printf(_("Histogram of timing durations:\n"));
- printf("%*s %*s %*s\n",
- Max(6, len1), header1,
- Max(10, len2), header2,
- Max(10, len3), header3);
-
- for (i = 0; i <= max_bit; i++)
- printf("%*ld %*.5f %*lld\n",
- Max(6, len1), 1l << i,
- Max(10, len2) - 1, (double) histogram[i] * 100 / loop_count,
- Max(10, len3), histogram[i]);
+ printf("%*s %*s %*s %*s\n",
+ len1, header1,
+ len2, header2,
+ len3, header3,
+ len4, header4);
+
+ rprct = 0;
+ for (int i = 0; i <= max_bit; i++)
+ {
+ double prct = (double) histogram[i] * 100 / loop_count;
+
+ rprct += prct;
+ printf("%*ld %*.4f %*.4f %*lld\n",
+ len1, (1L << i) - 1,
+ len2, prct,
+ len3, rprct,
+ len4, histogram[i]);
+ }
+
+ printf(_("\nObserved timing durations up to %.4f%%:\n"), max_rprct);
+ printf("%*s %*s %*s %*s\n",
+ len1, header1b,
+ len2, header2,
+ len3, header3,
+ len4, header4);
+
+ rprct = 0;
+ for (int i = 0; i < NUM_DIRECT; i++)
+ {
+ if (direct_histogram[i])
+ {
+ double prct = (double) direct_histogram[i] * 100 / loop_count;
+ bool print_it = !stopped;
+
+ rprct += prct;
+
+ /* if largest diff is < NUM_DIRECT, be sure we print it */
+ if (i == largest_diff)
+ {
+ if (stopped)
+ printf("...\n");
+ print_it = true;
+ }
+
+ if (print_it)
+ printf("%*d %*.4f %*.4f %*lld\n",
+ len1, i,
+ len2, prct,
+ len3, rprct,
+ len4, direct_histogram[i]);
+ if (rprct >= max_rprct)
+ stopped = true;
+ }
+ }
+
+ /* print largest diff when it's outside the array range */
+ if (largest_diff >= NUM_DIRECT)
+ {
+ double prct = (double) largest_diff_count * 100 / loop_count;
+
+ printf("...\n");
+ printf("%*d %*.4f %*.4f %*lld\n",
+ len1, largest_diff,
+ len2, prct,
+ len3, 100.0,
+ len4, largest_diff_count);
+ }
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-07-11 13:44:47 +0000