[PATCH] benchtests: Refactor pthread trylock throughput test (BZ #33704)
H.J. Lu
hjl.tools@gmail.com
Tue Dec 16 23:44:41 GMT 2025
On Wed, Dec 17, 2025 at 1:14 AM Sunil K Pandey <sunil.k.pandey@intel.com> wrote:
>
> Refactor pthread trylock throughput benchmark test.
> No functionality change.
> ---
> benchtests/bench-pthread-mutex-trylock-base.c | 176 ++++++++++++++++++
> .../bench-pthread-mutex-trylock-throughput.c | 160 +---------------
> 2 files changed, 178 insertions(+), 158 deletions(-)
> create mode 100644 benchtests/bench-pthread-mutex-trylock-base.c
>
> diff --git a/benchtests/bench-pthread-mutex-trylock-base.c b/benchtests/bench-pthread-mutex-trylock-base.c
> new file mode 100644
> index 0000000000..ef9c5a5b9f
> --- /dev/null
> +++ b/benchtests/bench-pthread-mutex-trylock-base.c
> @@ -0,0 +1,176 @@
> +/* Measure pthread trylock throughput under high cache contention.
> + Copyright (C) 2025 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <https://www.gnu.org/licenses/>. */
> +
> +#define TEST_MAIN
> +#define TIMEOUT (20 * 60)
> +
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <math.h>
> +#include <pthread.h>
> +#include <sys/time.h>
> +#include <sys/sysinfo.h>
> +#include "bench-timing.h"
> +#include "bench-util.h"
> +#include "json-lib.h"
> +
> +#define ITERS 10000000
> +#define RUN_COUNT 10
> +
> +pthread_mutex_t mutex = PTHREAD_MUTEX_TYPE_INITIALIZER;
> +
> +/* Shared counter only incremented by successful threads. */
> +int counter = 0;
> +
> +static void *
> +worker (void *v)
> +{
> + for (int i = 0; i < ITERS; i++)
> + if (pthread_mutex_trylock(&mutex) == 0)
> + {
> + counter++;
> + pthread_mutex_unlock(&mutex);
> + }
> + return NULL;
> +}
> +
> +static void
> +do_bench_one (const char *name, int num_threads, int nprocs, json_ctx_t *js)
> +{
> + struct timeval ts, te;
> + double tsd, ted, td, mean, stdev;
> + int i, j;
> + pthread_t *threads = malloc (num_threads * sizeof (pthread_t));
> +
> + /* Array to hold throughput(#updates/second) result of each run. We do
> + RUN_COUNT + 2 runs so that we can discard the highest and lowest as
> + outliers. */
> + double throughput_count[RUN_COUNT + 2];
> +
> + for (i = 0; i < RUN_COUNT + 2; i++)
> + {
> + /* Initialize counter before each run. */
> + counter = 0;
> + gettimeofday (&ts, NULL);
> +
> + for (j = 0; j < num_threads; j++)
> + pthread_create (&threads[j], NULL, worker, NULL);
> +
> + for (j = 0; j < num_threads; j++)
> + pthread_join (threads[j], NULL);
> + gettimeofday (&te, NULL);
> + tsd = ts.tv_sec + ts.tv_usec / 1000000.0;
> + ted = te.tv_sec + te.tv_usec / 1000000.0;
> + td = ted - tsd;
> +
> + /* Number of successful updates per second. */
> + throughput_count[i] = counter / td;
> + }
> +
> + free (threads);
> +
> + /* Sort the results so we can discard the largest and smallest
> + throughput as outliers. */
> + for (i = 0; i < RUN_COUNT + 1; i++)
> + for (j = i + 1; j < RUN_COUNT + 2; j++)
> + if (throughput_count[i] > throughput_count[j])
> + {
> + double temp = throughput_count[i];
> + throughput_count[i] = throughput_count[j];
> + throughput_count[j] = temp;
> + }
> +
> + /* Calculate mean and standard deviation. */
> + mean = 0;
> + for (i = 1; i < RUN_COUNT + 1; i++)
> + mean += throughput_count[i];
> + mean /= RUN_COUNT;
> +
> + stdev = 0.0;
> + for (i = 1; i < RUN_COUNT + 1; i++)
> + {
> + double s = throughput_count[i] - mean;
> + stdev += s * s;
> + }
> + stdev = sqrt (stdev / (RUN_COUNT - 1));
> +
> + char buf[256];
> + snprintf (buf, sizeof buf, "%s,threads=%d,HW threads=%d", name, num_threads,
> + nprocs);
> +
> + json_attr_object_begin (js, buf);
> +
> + json_attr_uint (js, "mean", mean);
> + json_attr_uint (js, "stdev", stdev);
> + json_attr_uint (js, "min-outlier", throughput_count[0]);
> + json_attr_uint (js, "min", throughput_count[1]);
> + json_attr_uint (js, "max", throughput_count[RUN_COUNT]);
> + json_attr_uint (js, "max-outlier", throughput_count[RUN_COUNT + 1]);
> +
> + json_attr_object_end (js);
> +}
> +
> +int
> +do_bench (void)
> +{
> + int rv = 0;
> + json_ctx_t json_ctx;
> + int th_num, th_conf, nprocs;
> + char name[128];
> +
> + json_init (&json_ctx, 2, stdout);
> + json_attr_object_begin (&json_ctx, TEST_NAME);
> +
> + /* The thread config begins from 2, and increases by 2x until nprocs.
> + We also want to test nprocs and over-saturation case 2*nprocs and
> + 4*nprocs. */
> + nprocs = get_nprocs ();
> +
> + /* Allocate [nprocs + 2] thread config array. */
> + int *threads = malloc ((nprocs + 2) * sizeof (int));
> +
> + th_num = 2;
> + for (th_conf = 0; th_num < nprocs; th_conf++)
> + {
> + threads[th_conf] = th_num;
> + th_num <<= 1;
> + }
> + threads[th_conf++] = nprocs;
> + threads[th_conf++] = nprocs * 2;
> + threads[th_conf++] = nprocs * 4;
> +
> + snprintf (name, sizeof name, "type=throughput(#updates/second)");
> +
> + for (int i = 0; i < th_conf; i++)
> + {
> + th_num = threads[i];
> + do_bench_one (name, th_num, nprocs, &json_ctx);
> + }
> +
> + free (threads);
> +
> + json_attr_object_end (&json_ctx);
> +
> + return rv;
> +}
> +
> +#define TEST_FUNCTION do_bench
> +
> +#include <support/test-driver.c>
> diff --git a/benchtests/bench-pthread-mutex-trylock-throughput.c b/benchtests/bench-pthread-mutex-trylock-throughput.c
> index f212e326b7..5e2f9957d2 100644
> --- a/benchtests/bench-pthread-mutex-trylock-throughput.c
> +++ b/benchtests/bench-pthread-mutex-trylock-throughput.c
> @@ -16,162 +16,6 @@
> License along with the GNU C Library; if not, see
> <https://www.gnu.org/licenses/>. */
>
> -#define TEST_MAIN
> -#define TIMEOUT (20 * 60)
> #define TEST_NAME "pthread-mutex-trylock-throughput"
> -
> -#include <stdio.h>
> -#include <stdlib.h>
> -#include <string.h>
> -#include <unistd.h>
> -#include <math.h>
> -#include <pthread.h>
> -#include <sys/time.h>
> -#include <sys/sysinfo.h>
> -#include "bench-timing.h"
> -#include "bench-util.h"
> -#include "json-lib.h"
> -
> -#define ITERS 10000000
> -#define RUN_COUNT 10
> -
> -pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
> -
> -/* Shared counter only incremented by successful threads. */
> -int counter = 0;
> -
> -static void *
> -worker (void *v)
> -{
> - for (int i = 0; i < ITERS; i++)
> - if (pthread_mutex_trylock(&mutex) == 0)
> - {
> - counter++;
> - pthread_mutex_unlock(&mutex);
> - }
> - return NULL;
> -}
> -
> -static void
> -do_bench_one (const char *name, int num_threads, int nprocs, json_ctx_t *js)
> -{
> - struct timeval ts, te;
> - double tsd, ted, td, mean, stdev;
> - int i, j;
> - pthread_t *threads = malloc (num_threads * sizeof (pthread_t));
> -
> - /* Array to hold throughput(#updates/second) result of each run. We do
> - RUN_COUNT + 2 runs so that we can discard the highest and lowest as
> - outliers. */
> - double throughput_count[RUN_COUNT + 2];
> -
> - for (i = 0; i < RUN_COUNT + 2; i++)
> - {
> - /* Initialize counter before each run. */
> - counter = 0;
> - gettimeofday (&ts, NULL);
> -
> - for (j = 0; j < num_threads; j++)
> - pthread_create (&threads[j], NULL, worker, NULL);
> -
> - for (j = 0; j < num_threads; j++)
> - pthread_join (threads[j], NULL);
> - gettimeofday (&te, NULL);
> - tsd = ts.tv_sec + ts.tv_usec / 1000000.0;
> - ted = te.tv_sec + te.tv_usec / 1000000.0;
> - td = ted - tsd;
> -
> - /* Number of successful updates per second. */
> - throughput_count[i] = counter / td;
> - }
> -
> - free (threads);
> -
> - /* Sort the results so we can discard the largest and smallest
> - throughput as outliers. */
> - for (i = 0; i < RUN_COUNT + 1; i++)
> - for (j = i + 1; j < RUN_COUNT + 2; j++)
> - if (throughput_count[i] > throughput_count[j])
> - {
> - double temp = throughput_count[i];
> - throughput_count[i] = throughput_count[j];
> - throughput_count[j] = temp;
> - }
> -
> - /* Calculate mean and standard deviation. */
> - mean = 0;
> - for (i = 1; i < RUN_COUNT + 1; i++)
> - mean += throughput_count[i];
> - mean /= RUN_COUNT;
> -
> - stdev = 0.0;
> - for (i = 1; i < RUN_COUNT + 1; i++)
> - {
> - double s = throughput_count[i] - mean;
> - stdev += s * s;
> - }
> - stdev = sqrt (stdev / (RUN_COUNT - 1));
> -
> - char buf[256];
> - snprintf (buf, sizeof buf, "%s,threads=%d,HW threads=%d", name, num_threads,
> - nprocs);
> -
> - json_attr_object_begin (js, buf);
> -
> - json_attr_uint (js, "mean", mean);
> - json_attr_uint (js, "stdev", stdev);
> - json_attr_uint (js, "min-outlier", throughput_count[0]);
> - json_attr_uint (js, "min", throughput_count[1]);
> - json_attr_uint (js, "max", throughput_count[RUN_COUNT]);
> - json_attr_uint (js, "max-outlier", throughput_count[RUN_COUNT + 1]);
> -
> - json_attr_object_end (js);
> -}
> -
> -int
> -do_bench (void)
> -{
> - int rv = 0;
> - json_ctx_t json_ctx;
> - int th_num, th_conf, nprocs;
> - char name[128];
> -
> - json_init (&json_ctx, 2, stdout);
> - json_attr_object_begin (&json_ctx, TEST_NAME);
> -
> - /* The thread config begins from 2, and increases by 2x until nprocs.
> - We also want to test nprocs and over-saturation case 2*nprocs and
> - 4*nprocs. */
> - nprocs = get_nprocs ();
> -
> - /* Allocate [nprocs + 2] thread config array. */
> - int *threads = malloc ((nprocs + 2) * sizeof (int));
> -
> - th_num = 2;
> - for (th_conf = 0; th_num < nprocs; th_conf++)
> - {
> - threads[th_conf] = th_num;
> - th_num <<= 1;
> - }
> - threads[th_conf++] = nprocs;
> - threads[th_conf++] = nprocs * 2;
> - threads[th_conf++] = nprocs * 4;
> -
> - snprintf (name, sizeof name, "type=throughput(#updates/second)");
> -
> - for (int i = 0; i < th_conf; i++)
> - {
> - th_num = threads[i];
> - do_bench_one (name, th_num, nprocs, &json_ctx);
> - }
> -
> - free (threads);
> -
> - json_attr_object_end (&json_ctx);
> -
> - return rv;
> -}
> -
> -#define TEST_FUNCTION do_bench
> -
> -#include <support/test-driver.c>
> +#define PTHREAD_MUTEX_TYPE_INITIALIZER PTHREAD_MUTEX_INITIALIZER
> +#include "bench-pthread-mutex-trylock-base.c"
> --
> 2.51.0
>
LGTM.
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
Thanks.
--
H.J.
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