1 files changed, 238 insertions, 0 deletions
diff --git a/tools/perf/bench/futex-wake.c b/tools/perf/bench/futex-wake.c
new file mode 100644
index 000000000..9ecab6620
--- /dev/null
+++ b/tools/perf/bench/futex-wake.c
@@ -0,0 +1,238 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2013  Davidlohr Bueso <davidlohr@hp.com>
+ *
+ * futex-wake: Block a bunch of threads on a futex and wake'em up, N at a time.
+ *
+ * This program is particularly useful to measure the latency of nthread wakeups
+ * in non-error situations:  all waiters are queued and all wake calls wakeup
+ * one or more tasks, and thus the waitqueue is never empty.
+ */
+
+/* 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>
+
+/* all threads will block on the same futex */
+static u_int32_t futex1 = 0;
+
+static pthread_t *worker;
+static bool done = false;
+static struct mutex thread_lock;
+static struct cond thread_parent, thread_worker;
+static struct stats waketime_stats, wakeup_stats;
+static unsigned int threads_starting;
+static int futex_flag = 0;
+
+static struct bench_futex_parameters params = {
+	/*
+	 * How many wakeups to do at a time.
+	 * Default to 1 in order to make the kernel work more.
+	 */
+	.nwakes  = 1,
+};
+
+static const struct option options[] = {
+	OPT_UINTEGER('t', "threads", &params.nthreads, "Specify amount of threads"),
+	OPT_UINTEGER('w', "nwakes",  &params.nwakes, "Specify amount of threads to wake 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_END()
+};
+
+static const char * const bench_futex_wake_usage[] = {
+	"perf bench futex wake <options>",
+	NULL
+};
+
+static void *workerfn(void *arg __maybe_unused)
+{
+	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 (futex_wait(&futex1, 0, NULL, futex_flag) != EINTR)
+			break;
+	}
+
+	pthread_exit(NULL);
+	return NULL;
+}
+
+static void print_summary(void)
+{
+	double waketime_avg = avg_stats(&waketime_stats);
+	double waketime_stddev = stddev_stats(&waketime_stats);
+	unsigned int wakeup_avg = avg_stats(&wakeup_stats);
+
+	printf("Wokeup %d of %d threads in %.4f ms (+-%.2f%%)\n",
+	       wakeup_avg,
+	       params.nthreads,
+	       waketime_avg / USEC_PER_MSEC,
+	       rel_stddev_stats(waketime_stddev, waketime_avg));
+}
+
+static void block_threads(pthread_t *w,
+			  pthread_attr_t thread_attr, struct perf_cpu_map *cpu)
+{
+	cpu_set_t *cpuset;
+	unsigned int i;
+	size_t size;
+	int nrcpus = perf_cpu_map__nr(cpu);
+	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_wake(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_wake_usage, 0);
+	if (argc) {
+		usage_with_options(bench_futex_wake_usage, options);
+		exit(EXIT_FAILURE);
+	}
+
+	cpu = perf_cpu_map__new(NULL);
+	if (!cpu)
+		err(EXIT_FAILURE, "calloc");
+
+	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;
+
+	printf("Run summary [PID %d]: blocking on %d threads (at [%s] futex %p), "
+	       "waking up %d at a time.\n\n",
+	       getpid(), params.nthreads, params.fshared ? "shared":"private",
+	       &futex1, params.nwakes);
+
+	init_stats(&wakeup_stats);
+	init_stats(&waketime_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 nwoken = 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 waking folks up */
+		gettimeofday(&start, NULL);
+		while (nwoken != params.nthreads)
+			nwoken += futex_wake(&futex1,
+					     params.nwakes, futex_flag);
+		gettimeofday(&end, NULL);
+		timersub(&end, &start, &runtime);
+
+		update_stats(&wakeup_stats, nwoken);
+		update_stats(&waketime_stats, runtime.tv_usec);
+
+		if (!params.silent) {
+			printf("[Run %d]: Wokeup %d of %d threads in %.4f ms\n",
+			       j + 1, nwoken, params.nthreads,
+			       runtime.tv_usec / (double)USEC_PER_MSEC);
+		}
+
+		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;
+}