tools/perf/bench/futex-wake-parallel.c - kernel/quantenna - Git at Google

 /*
  * Copyright (C) 2015 Davidlohr Bueso.
  *
  * Block a bunch of threads and let parallel waker threads wakeup an
  * equal amount of them. The program output reflects the avg latency
  * for each individual thread to service its share of work. Ultimately
  * it can be used to measure futex_wake() changes.
  */

 #include "../perf.h"
 #include "../util/util.h"
 #include "../util/stat.h"
 #include <subcmd/parse-options.h>
 #include "../util/header.h"
 #include "bench.h"
 #include "futex.h"

 #include <err.h>
 #include <stdlib.h>
 #include <sys/time.h>
 #include <pthread.h>

 struct thread_data {
 	pthread_t worker;
 	unsigned int nwoken;
 	struct timeval runtime;
 };

 static unsigned int nwakes = 1;

 /* all threads will block on the same futex -- hash bucket chaos ;) */
 static u_int32_t futex = 0;

 static pthread_t *blocked_worker;
 static bool done = false, silent = false, fshared = false;
 static unsigned int nblocked_threads = 0, nwaking_threads = 0;
 static pthread_mutex_t thread_lock;
 static pthread_cond_t thread_parent, thread_worker;
 static struct stats waketime_stats, wakeup_stats;
 static unsigned int ncpus, threads_starting;
 static int futex_flag = 0;

 static const struct option options[] = {
 	OPT_UINTEGER('t', "threads", &nblocked_threads, "Specify amount of threads"),
 	OPT_UINTEGER('w', "nwakers", &nwaking_threads, "Specify amount of waking threads"),
 	OPT_BOOLEAN( 's', "silent",  &silent,   "Silent mode: do not display data/details"),
 	OPT_BOOLEAN( 'S', "shared",  &fshared,  "Use shared futexes instead of private ones"),
 	OPT_END()
 };

 static const char * const bench_futex_wake_parallel_usage[] = {
 	"perf bench futex wake-parallel <options>",
 	NULL
 };

 static void *waking_workerfn(void *arg)
 {
 	struct thread_data *waker = (struct thread_data *) arg;
 	struct timeval start, end;

 	gettimeofday(&start, NULL);

 	waker->nwoken = futex_wake(&futex, nwakes, futex_flag);
 	if (waker->nwoken != nwakes)
 		warnx("couldn't wakeup all tasks (%d/%d)",
 		      waker->nwoken, nwakes);

 	gettimeofday(&end, NULL);
 	timersub(&end, &start, &waker->runtime);

 	pthread_exit(NULL);
 	return NULL;
 }

 static void wakeup_threads(struct thread_data *td, pthread_attr_t thread_attr)
 {
 	unsigned int i;

 	pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_JOINABLE);

 	/* create and block all threads */
 	for (i = 0; i < nwaking_threads; i++) {
 		/*
 		 * Thread creation order will impact per-thread latency
 		 * as it will affect the order to acquire the hb spinlock.
 		 * For now let the scheduler decide.
 		 */
 		if (pthread_create(&td[i].worker, &thread_attr,
 				   waking_workerfn, (void *)&td[i]))
 			err(EXIT_FAILURE, "pthread_create");
 	}

 	for (i = 0; i < nwaking_threads; i++)
 		if (pthread_join(td[i].worker, NULL))
 			err(EXIT_FAILURE, "pthread_join");
 }

 static void *blocked_workerfn(void *arg __maybe_unused)
 {
 	pthread_mutex_lock(&thread_lock);
 	threads_starting--;
 	if (!threads_starting)
 		pthread_cond_signal(&thread_parent);
 	pthread_cond_wait(&thread_worker, &thread_lock);
 	pthread_mutex_unlock(&thread_lock);

 	while (1) { /* handle spurious wakeups */
 		if (futex_wait(&futex, 0, NULL, futex_flag) != EINTR)
 			break;
 	}

 	pthread_exit(NULL);
 	return NULL;
 }

 static void block_threads(pthread_t *w, pthread_attr_t thread_attr)
 {
 	cpu_set_t cpu;
 	unsigned int i;

 	threads_starting = nblocked_threads;

 	/* create and block all threads */
 	for (i = 0; i < nblocked_threads; i++) {
 		CPU_ZERO(&cpu);
 		CPU_SET(i % ncpus, &cpu);

 		if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu))
 			err(EXIT_FAILURE, "pthread_attr_setaffinity_np");

 		if (pthread_create(&w[i], &thread_attr, blocked_workerfn, NULL))
 			err(EXIT_FAILURE, "pthread_create");
 	}
 }

 static void print_run(struct thread_data *waking_worker, unsigned int run_num)
 {
 	unsigned int i, wakeup_avg;
 	double waketime_avg, waketime_stddev;
 	struct stats __waketime_stats, __wakeup_stats;

 	init_stats(&__wakeup_stats);
 	init_stats(&__waketime_stats);

 	for (i = 0; i < nwaking_threads; i++) {
 		update_stats(&__waketime_stats, waking_worker[i].runtime.tv_usec);
 		update_stats(&__wakeup_stats, waking_worker[i].nwoken);
 	}

 	waketime_avg = avg_stats(&__waketime_stats);
 	waketime_stddev = stddev_stats(&__waketime_stats);
 	wakeup_avg = avg_stats(&__wakeup_stats);

 	printf("[Run %d]: Avg per-thread latency (waking %d/%d threads) "
 	       "in %.4f ms (+-%.2f%%)\n", run_num + 1, wakeup_avg,
 	       nblocked_threads, waketime_avg/1e3,
 	       rel_stddev_stats(waketime_stddev, waketime_avg));
 }

 static void print_summary(void)
 {
 	unsigned int wakeup_avg;
 	double waketime_avg, waketime_stddev;

 	waketime_avg = avg_stats(&waketime_stats);
 	waketime_stddev = stddev_stats(&waketime_stats);
 	wakeup_avg = avg_stats(&wakeup_stats);

 	printf("Avg per-thread latency (waking %d/%d threads) in %.4f ms (+-%.2f%%)\n",
 	       wakeup_avg,
 	       nblocked_threads,
 	       waketime_avg/1e3,
 	       rel_stddev_stats(waketime_stddev, waketime_avg));
 }


 static void do_run_stats(struct thread_data *waking_worker)
 {
 	unsigned int i;

 	for (i = 0; i < nwaking_threads; i++) {
 		update_stats(&waketime_stats, waking_worker[i].runtime.tv_usec);
 		update_stats(&wakeup_stats, waking_worker[i].nwoken);
 	}

 }

 static void toggle_done(int sig __maybe_unused,
 			siginfo_t *info __maybe_unused,
 			void *uc __maybe_unused)
 {
 	done = true;
 }

 int bench_futex_wake_parallel(int argc, const char **argv,
 			      const char *prefix __maybe_unused)
 {
 	int ret = 0;
 	unsigned int i, j;
 	struct sigaction act;
 	pthread_attr_t thread_attr;
 	struct thread_data *waking_worker;

 	argc = parse_options(argc, argv, options,
 			     bench_futex_wake_parallel_usage, 0);
 	if (argc) {
 		usage_with_options(bench_futex_wake_parallel_usage, options);
 		exit(EXIT_FAILURE);
 	}

 	sigfillset(&act.sa_mask);
 	act.sa_sigaction = toggle_done;
 	sigaction(SIGINT, &act, NULL);

 	ncpus = sysconf(_SC_NPROCESSORS_ONLN);
 	if (!nblocked_threads)
 		nblocked_threads = ncpus;

 	/* some sanity checks */
 	if (nwaking_threads > nblocked_threads || !nwaking_threads)
 		nwaking_threads = nblocked_threads;

 	if (nblocked_threads % nwaking_threads)
 		errx(EXIT_FAILURE, "Must be perfectly divisible");
 	/*
 	 * Each thread will wakeup nwakes tasks in
 	 * a single futex_wait call.
 	 */
 	nwakes = nblocked_threads/nwaking_threads;

 	blocked_worker = calloc(nblocked_threads, sizeof(*blocked_worker));
 	if (!blocked_worker)
 		err(EXIT_FAILURE, "calloc");

 	if (!fshared)
 		futex_flag = FUTEX_PRIVATE_FLAG;

 	printf("Run summary [PID %d]: blocking on %d threads (at [%s] "
 	       "futex %p), %d threads waking up %d at a time.\n\n",
 	       getpid(), nblocked_threads, fshared ? "shared":"private",
 	       &futex, nwaking_threads, nwakes);

 	init_stats(&wakeup_stats);
 	init_stats(&waketime_stats);

 	pthread_attr_init(&thread_attr);
 	pthread_mutex_init(&thread_lock, NULL);
 	pthread_cond_init(&thread_parent, NULL);
 	pthread_cond_init(&thread_worker, NULL);

 	for (j = 0; j < bench_repeat && !done; j++) {
 		waking_worker = calloc(nwaking_threads, sizeof(*waking_worker));
 		if (!waking_worker)
 			err(EXIT_FAILURE, "calloc");

 		/* create, launch & block all threads */
 		block_threads(blocked_worker, thread_attr);

 		/* make sure all threads are already blocked */
 		pthread_mutex_lock(&thread_lock);
 		while (threads_starting)
 			pthread_cond_wait(&thread_parent, &thread_lock);
 		pthread_cond_broadcast(&thread_worker);
 		pthread_mutex_unlock(&thread_lock);

 		usleep(100000);

 		/* Ok, all threads are patiently blocked, start waking folks up */
 		wakeup_threads(waking_worker, thread_attr);

 		for (i = 0; i < nblocked_threads; i++) {
 			ret = pthread_join(blocked_worker[i], NULL);
 			if (ret)
 				err(EXIT_FAILURE, "pthread_join");
 		}

 		do_run_stats(waking_worker);
 		if (!silent)
 			print_run(waking_worker, j);

 		free(waking_worker);
 	}

 	/* cleanup & report results */
 	pthread_cond_destroy(&thread_parent);
 	pthread_cond_destroy(&thread_worker);
 	pthread_mutex_destroy(&thread_lock);
 	pthread_attr_destroy(&thread_attr);

 	print_summary();

 	free(blocked_worker);
 	return ret;
 }
	/*
	* Copyright (C) 2015 Davidlohr Bueso.
	*
	* Block a bunch of threads and let parallel waker threads wakeup an
	* equal amount of them. The program output reflects the avg latency
	* for each individual thread to service its share of work. Ultimately
	* it can be used to measure futex_wake() changes.
	*/

	#include "../perf.h"
	#include "../util/util.h"
	#include "../util/stat.h"
	#include <subcmd/parse-options.h>
	#include "../util/header.h"
	#include "bench.h"
	#include "futex.h"

	#include <err.h>
	#include <stdlib.h>
	#include <sys/time.h>
	#include <pthread.h>

	struct thread_data {
	pthread_t worker;
	unsigned int nwoken;
	struct timeval runtime;
	};

	static unsigned int nwakes = 1;

	/* all threads will block on the same futex -- hash bucket chaos ;) */
	static u_int32_t futex = 0;

	static pthread_t *blocked_worker;
	static bool done = false, silent = false, fshared = false;
	static unsigned int nblocked_threads = 0, nwaking_threads = 0;
	static pthread_mutex_t thread_lock;
	static pthread_cond_t thread_parent, thread_worker;
	static struct stats waketime_stats, wakeup_stats;
	static unsigned int ncpus, threads_starting;
	static int futex_flag = 0;

	static const struct option options[] = {
	OPT_UINTEGER('t', "threads", &nblocked_threads, "Specify amount of threads"),
	OPT_UINTEGER('w', "nwakers", &nwaking_threads, "Specify amount of waking threads"),
	OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"),
	OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"),
	OPT_END()
	};

	static const char * const bench_futex_wake_parallel_usage[] = {
	"perf bench futex wake-parallel <options>",
	NULL
	};

	static void waking_workerfn(void arg)
	{
	struct thread_data waker = (struct thread_data ) arg;
	struct timeval start, end;

	gettimeofday(&start, NULL);

	waker->nwoken = futex_wake(&futex, nwakes, futex_flag);
	if (waker->nwoken != nwakes)
	warnx("couldn't wakeup all tasks (%d/%d)",
	waker->nwoken, nwakes);

	gettimeofday(&end, NULL);
	timersub(&end, &start, &waker->runtime);

	pthread_exit(NULL);
	return NULL;
	}

	static void wakeup_threads(struct thread_data *td, pthread_attr_t thread_attr)
	{
	unsigned int i;

	pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_JOINABLE);

	/* create and block all threads */
	for (i = 0; i < nwaking_threads; i++) {
	/*
	* Thread creation order will impact per-thread latency
	* as it will affect the order to acquire the hb spinlock.
	* For now let the scheduler decide.
	*/
	if (pthread_create(&td[i].worker, &thread_attr,
	waking_workerfn, (void *)&td[i]))
	err(EXIT_FAILURE, "pthread_create");
	}

	for (i = 0; i < nwaking_threads; i++)
	if (pthread_join(td[i].worker, NULL))
	err(EXIT_FAILURE, "pthread_join");
	}

	static void blocked_workerfn(void arg __maybe_unused)
	{
	pthread_mutex_lock(&thread_lock);
	threads_starting--;
	if (!threads_starting)
	pthread_cond_signal(&thread_parent);
	pthread_cond_wait(&thread_worker, &thread_lock);
	pthread_mutex_unlock(&thread_lock);

	while (1) { /* handle spurious wakeups */
	if (futex_wait(&futex, 0, NULL, futex_flag) != EINTR)
	break;
	}

	pthread_exit(NULL);
	return NULL;
	}

	static void block_threads(pthread_t *w, pthread_attr_t thread_attr)
	{
	cpu_set_t cpu;
	unsigned int i;

	threads_starting = nblocked_threads;

	/* create and block all threads */
	for (i = 0; i < nblocked_threads; i++) {
	CPU_ZERO(&cpu);
	CPU_SET(i % ncpus, &cpu);

	if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu))
	err(EXIT_FAILURE, "pthread_attr_setaffinity_np");

	if (pthread_create(&w[i], &thread_attr, blocked_workerfn, NULL))
	err(EXIT_FAILURE, "pthread_create");
	}
	}

	static void print_run(struct thread_data *waking_worker, unsigned int run_num)
	{
	unsigned int i, wakeup_avg;
	double waketime_avg, waketime_stddev;
	struct stats __waketime_stats, __wakeup_stats;

	init_stats(&__wakeup_stats);
	init_stats(&__waketime_stats);

	for (i = 0; i < nwaking_threads; i++) {
	update_stats(&__waketime_stats, waking_worker[i].runtime.tv_usec);
	update_stats(&__wakeup_stats, waking_worker[i].nwoken);
	}

	waketime_avg = avg_stats(&__waketime_stats);
	waketime_stddev = stddev_stats(&__waketime_stats);
	wakeup_avg = avg_stats(&__wakeup_stats);

	printf("[Run %d]: Avg per-thread latency (waking %d/%d threads) "
	"in %.4f ms (+-%.2f%%)\n", run_num + 1, wakeup_avg,
	nblocked_threads, waketime_avg/1e3,
	rel_stddev_stats(waketime_stddev, waketime_avg));
	}

	static void print_summary(void)
	{
	unsigned int wakeup_avg;
	double waketime_avg, waketime_stddev;

	waketime_avg = avg_stats(&waketime_stats);
	waketime_stddev = stddev_stats(&waketime_stats);
	wakeup_avg = avg_stats(&wakeup_stats);

	printf("Avg per-thread latency (waking %d/%d threads) in %.4f ms (+-%.2f%%)\n",
	wakeup_avg,
	nblocked_threads,
	waketime_avg/1e3,
	rel_stddev_stats(waketime_stddev, waketime_avg));
	}


	static void do_run_stats(struct thread_data *waking_worker)
	{
	unsigned int i;

	for (i = 0; i < nwaking_threads; i++) {
	update_stats(&waketime_stats, waking_worker[i].runtime.tv_usec);
	update_stats(&wakeup_stats, waking_worker[i].nwoken);
	}

	}

	static void toggle_done(int sig __maybe_unused,
	siginfo_t *info __maybe_unused,
	void *uc __maybe_unused)
	{
	done = true;
	}

	int bench_futex_wake_parallel(int argc, const char **argv,
	const char *prefix __maybe_unused)
	{
	int ret = 0;
	unsigned int i, j;
	struct sigaction act;
	pthread_attr_t thread_attr;
	struct thread_data *waking_worker;

	argc = parse_options(argc, argv, options,
	bench_futex_wake_parallel_usage, 0);
	if (argc) {
	usage_with_options(bench_futex_wake_parallel_usage, options);
	exit(EXIT_FAILURE);
	}

	sigfillset(&act.sa_mask);
	act.sa_sigaction = toggle_done;
	sigaction(SIGINT, &act, NULL);

	ncpus = sysconf(_SC_NPROCESSORS_ONLN);
	if (!nblocked_threads)
	nblocked_threads = ncpus;

	/* some sanity checks */
	if (nwaking_threads > nblocked_threads \|\| !nwaking_threads)
	nwaking_threads = nblocked_threads;

	if (nblocked_threads % nwaking_threads)
	errx(EXIT_FAILURE, "Must be perfectly divisible");
	/*
	* Each thread will wakeup nwakes tasks in
	* a single futex_wait call.
	*/
	nwakes = nblocked_threads/nwaking_threads;

	blocked_worker = calloc(nblocked_threads, sizeof(*blocked_worker));
	if (!blocked_worker)
	err(EXIT_FAILURE, "calloc");

	if (!fshared)
	futex_flag = FUTEX_PRIVATE_FLAG;

	printf("Run summary [PID %d]: blocking on %d threads (at [%s] "
	"futex %p), %d threads waking up %d at a time.\n\n",
	getpid(), nblocked_threads, fshared ? "shared":"private",
	&futex, nwaking_threads, nwakes);

	init_stats(&wakeup_stats);
	init_stats(&waketime_stats);

	pthread_attr_init(&thread_attr);
	pthread_mutex_init(&thread_lock, NULL);
	pthread_cond_init(&thread_parent, NULL);
	pthread_cond_init(&thread_worker, NULL);

	for (j = 0; j < bench_repeat && !done; j++) {
	waking_worker = calloc(nwaking_threads, sizeof(*waking_worker));
	if (!waking_worker)
	err(EXIT_FAILURE, "calloc");

	/* create, launch & block all threads */
	block_threads(blocked_worker, thread_attr);

	/* make sure all threads are already blocked */
	pthread_mutex_lock(&thread_lock);
	while (threads_starting)
	pthread_cond_wait(&thread_parent, &thread_lock);
	pthread_cond_broadcast(&thread_worker);
	pthread_mutex_unlock(&thread_lock);

	usleep(100000);

	/* Ok, all threads are patiently blocked, start waking folks up */
	wakeup_threads(waking_worker, thread_attr);

	for (i = 0; i < nblocked_threads; i++) {
	ret = pthread_join(blocked_worker[i], NULL);
	if (ret)
	err(EXIT_FAILURE, "pthread_join");
	}

	do_run_stats(waking_worker);
	if (!silent)
	print_run(waking_worker, j);

	free(waking_worker);
	}

	/* cleanup & report results */
	pthread_cond_destroy(&thread_parent);
	pthread_cond_destroy(&thread_worker);
	pthread_mutex_destroy(&thread_lock);
	pthread_attr_destroy(&thread_attr);

	print_summary();

	free(blocked_worker);
	return ret;
	}