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-rw-r--r--tools/perf/bench/futex-requeue.c314
1 files changed, 314 insertions, 0 deletions
diff --git a/tools/perf/bench/futex-requeue.c b/tools/perf/bench/futex-requeue.c
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index 000000000..69ad896f5
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+++ 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", &params.nthreads, "Specify amount of threads"),
+ OPT_UINTEGER('q', "nrequeue", &params.nrequeue, "Specify amount of threads to requeue at once"),
+ OPT_BOOLEAN( 's', "silent", &params.silent, "Silent mode: do not display data/details"),
+ OPT_BOOLEAN( 'S', "shared", &params.fshared, "Use shared futexes instead of private ones"),
+ OPT_BOOLEAN( 'm', "mlockall", &params.mlockall, "Lock all current and future memory"),
+ OPT_BOOLEAN( 'B', "broadcast", &params.broadcast, "Requeue all threads at once"),
+ OPT_BOOLEAN( 'p', "pi", &params.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);
+}
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