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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:49:45 +0000 |
commit | 2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch) | |
tree | 848558de17fb3008cdf4d861b01ac7781903ce39 /tools/perf/bench/futex-requeue.c | |
parent | Initial commit. (diff) | |
download | linux-upstream.tar.xz linux-upstream.zip |
Adding upstream version 6.1.76.upstream/6.1.76upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'tools/perf/bench/futex-requeue.c')
-rw-r--r-- | tools/perf/bench/futex-requeue.c | 314 |
1 files changed, 314 insertions, 0 deletions
diff --git a/tools/perf/bench/futex-requeue.c b/tools/perf/bench/futex-requeue.c new file mode 100644 index 000000000..69ad896f5 --- /dev/null +++ b/tools/perf/bench/futex-requeue.c @@ -0,0 +1,314 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2013 Davidlohr Bueso <davidlohr@hp.com> + * + * futex-requeue: Block a bunch of threads on futex1 and requeue them + * on futex2, N at a time. + * + * This program is particularly useful to measure the latency of nthread + * requeues without waking up any tasks (in the non-pi case) -- thus + * mimicking a regular futex_wait. + */ + +/* For the CLR_() macros */ +#include <string.h> +#include <pthread.h> + +#include <signal.h> +#include "../util/mutex.h" +#include "../util/stat.h" +#include <subcmd/parse-options.h> +#include <linux/compiler.h> +#include <linux/kernel.h> +#include <linux/time64.h> +#include <errno.h> +#include <perf/cpumap.h> +#include "bench.h" +#include "futex.h" + +#include <err.h> +#include <stdlib.h> +#include <sys/time.h> +#include <sys/mman.h> + +static u_int32_t futex1 = 0, futex2 = 0; + +static pthread_t *worker; +static bool done = false; +static struct mutex thread_lock; +static struct cond thread_parent, thread_worker; +static struct stats requeuetime_stats, requeued_stats; +static unsigned int threads_starting; +static int futex_flag = 0; + +static struct bench_futex_parameters params = { + /* + * How many tasks to requeue at a time. + * Default to 1 in order to make the kernel work more. + */ + .nrequeue = 1, +}; + +static const struct option options[] = { + OPT_UINTEGER('t', "threads", ¶ms.nthreads, "Specify amount of threads"), + OPT_UINTEGER('q', "nrequeue", ¶ms.nrequeue, "Specify amount of threads to requeue at once"), + OPT_BOOLEAN( 's', "silent", ¶ms.silent, "Silent mode: do not display data/details"), + OPT_BOOLEAN( 'S', "shared", ¶ms.fshared, "Use shared futexes instead of private ones"), + OPT_BOOLEAN( 'm', "mlockall", ¶ms.mlockall, "Lock all current and future memory"), + OPT_BOOLEAN( 'B', "broadcast", ¶ms.broadcast, "Requeue all threads at once"), + OPT_BOOLEAN( 'p', "pi", ¶ms.pi, "Use PI-aware variants of FUTEX_CMP_REQUEUE"), + + OPT_END() +}; + +static const char * const bench_futex_requeue_usage[] = { + "perf bench futex requeue <options>", + NULL +}; + +static void print_summary(void) +{ + double requeuetime_avg = avg_stats(&requeuetime_stats); + double requeuetime_stddev = stddev_stats(&requeuetime_stats); + unsigned int requeued_avg = avg_stats(&requeued_stats); + + printf("Requeued %d of %d threads in %.4f ms (+-%.2f%%)\n", + requeued_avg, + params.nthreads, + requeuetime_avg / USEC_PER_MSEC, + rel_stddev_stats(requeuetime_stddev, requeuetime_avg)); +} + +static void *workerfn(void *arg __maybe_unused) +{ + int ret; + + mutex_lock(&thread_lock); + threads_starting--; + if (!threads_starting) + cond_signal(&thread_parent); + cond_wait(&thread_worker, &thread_lock); + mutex_unlock(&thread_lock); + + while (1) { + if (!params.pi) { + ret = futex_wait(&futex1, 0, NULL, futex_flag); + if (!ret) + break; + + if (ret && errno != EAGAIN) { + if (!params.silent) + warnx("futex_wait"); + break; + } + } else { + ret = futex_wait_requeue_pi(&futex1, 0, &futex2, + NULL, futex_flag); + if (!ret) { + /* got the lock at futex2 */ + futex_unlock_pi(&futex2, futex_flag); + break; + } + + if (ret && errno != EAGAIN) { + if (!params.silent) + warnx("futex_wait_requeue_pi"); + break; + } + } + } + + return NULL; +} + +static void block_threads(pthread_t *w, + pthread_attr_t thread_attr, struct perf_cpu_map *cpu) +{ + cpu_set_t *cpuset; + unsigned int i; + int nrcpus = perf_cpu_map__nr(cpu); + size_t size; + + threads_starting = params.nthreads; + + cpuset = CPU_ALLOC(nrcpus); + BUG_ON(!cpuset); + size = CPU_ALLOC_SIZE(nrcpus); + + /* create and block all threads */ + for (i = 0; i < params.nthreads; i++) { + CPU_ZERO_S(size, cpuset); + CPU_SET_S(perf_cpu_map__cpu(cpu, i % perf_cpu_map__nr(cpu)).cpu, size, cpuset); + + if (pthread_attr_setaffinity_np(&thread_attr, size, cpuset)) { + CPU_FREE(cpuset); + err(EXIT_FAILURE, "pthread_attr_setaffinity_np"); + } + + if (pthread_create(&w[i], &thread_attr, workerfn, NULL)) { + CPU_FREE(cpuset); + err(EXIT_FAILURE, "pthread_create"); + } + } + CPU_FREE(cpuset); +} + +static void toggle_done(int sig __maybe_unused, + siginfo_t *info __maybe_unused, + void *uc __maybe_unused) +{ + done = true; +} + +int bench_futex_requeue(int argc, const char **argv) +{ + int ret = 0; + unsigned int i, j; + struct sigaction act; + pthread_attr_t thread_attr; + struct perf_cpu_map *cpu; + + argc = parse_options(argc, argv, options, bench_futex_requeue_usage, 0); + if (argc) + goto err; + + cpu = perf_cpu_map__new(NULL); + if (!cpu) + err(EXIT_FAILURE, "cpu_map__new"); + + memset(&act, 0, sizeof(act)); + sigfillset(&act.sa_mask); + act.sa_sigaction = toggle_done; + sigaction(SIGINT, &act, NULL); + + if (params.mlockall) { + if (mlockall(MCL_CURRENT | MCL_FUTURE)) + err(EXIT_FAILURE, "mlockall"); + } + + if (!params.nthreads) + params.nthreads = perf_cpu_map__nr(cpu); + + worker = calloc(params.nthreads, sizeof(*worker)); + if (!worker) + err(EXIT_FAILURE, "calloc"); + + if (!params.fshared) + futex_flag = FUTEX_PRIVATE_FLAG; + + if (params.nrequeue > params.nthreads) + params.nrequeue = params.nthreads; + + if (params.broadcast) + params.nrequeue = params.nthreads; + + printf("Run summary [PID %d]: Requeuing %d threads (from [%s] %p to %s%p), " + "%d at a time.\n\n", getpid(), params.nthreads, + params.fshared ? "shared":"private", &futex1, + params.pi ? "PI ": "", &futex2, params.nrequeue); + + init_stats(&requeued_stats); + init_stats(&requeuetime_stats); + pthread_attr_init(&thread_attr); + mutex_init(&thread_lock); + cond_init(&thread_parent); + cond_init(&thread_worker); + + for (j = 0; j < bench_repeat && !done; j++) { + unsigned int nrequeued = 0, wakeups = 0; + struct timeval start, end, runtime; + + /* create, launch & block all threads */ + block_threads(worker, thread_attr, cpu); + + /* make sure all threads are already blocked */ + mutex_lock(&thread_lock); + while (threads_starting) + cond_wait(&thread_parent, &thread_lock); + cond_broadcast(&thread_worker); + mutex_unlock(&thread_lock); + + usleep(100000); + + /* Ok, all threads are patiently blocked, start requeueing */ + gettimeofday(&start, NULL); + while (nrequeued < params.nthreads) { + int r; + + /* + * For the regular non-pi case, do not wakeup any tasks + * blocked on futex1, allowing us to really measure + * futex_wait functionality. For the PI case the first + * waiter is always awoken. + */ + if (!params.pi) { + r = futex_cmp_requeue(&futex1, 0, &futex2, 0, + params.nrequeue, + futex_flag); + } else { + r = futex_cmp_requeue_pi(&futex1, 0, &futex2, + params.nrequeue, + futex_flag); + wakeups++; /* assume no error */ + } + + if (r < 0) + err(EXIT_FAILURE, "couldn't requeue from %p to %p", + &futex1, &futex2); + + nrequeued += r; + } + + gettimeofday(&end, NULL); + timersub(&end, &start, &runtime); + + update_stats(&requeued_stats, nrequeued); + update_stats(&requeuetime_stats, runtime.tv_usec); + + if (!params.silent) { + if (!params.pi) + printf("[Run %d]: Requeued %d of %d threads in " + "%.4f ms\n", j + 1, nrequeued, + params.nthreads, + runtime.tv_usec / (double)USEC_PER_MSEC); + else { + nrequeued -= wakeups; + printf("[Run %d]: Awoke and Requeued (%d+%d) of " + "%d threads in %.4f ms\n", + j + 1, wakeups, nrequeued, + params.nthreads, + runtime.tv_usec / (double)USEC_PER_MSEC); + } + + } + + if (!params.pi) { + /* everybody should be blocked on futex2, wake'em up */ + nrequeued = futex_wake(&futex2, nrequeued, futex_flag); + if (params.nthreads != nrequeued) + warnx("couldn't wakeup all tasks (%d/%d)", + nrequeued, params.nthreads); + } + + for (i = 0; i < params.nthreads; i++) { + ret = pthread_join(worker[i], NULL); + if (ret) + err(EXIT_FAILURE, "pthread_join"); + } + } + + /* cleanup & report results */ + cond_destroy(&thread_parent); + cond_destroy(&thread_worker); + mutex_destroy(&thread_lock); + pthread_attr_destroy(&thread_attr); + + print_summary(); + + free(worker); + perf_cpu_map__put(cpu); + return ret; +err: + usage_with_options(bench_futex_requeue_usage, options); + exit(EXIT_FAILURE); +} |