1/*
  2 * Copyright (C) 2015 Davidlohr Bueso.
  3 */
  4
  5#include "../perf.h"
  6#include "../util/util.h"
  7#include "../util/stat.h"
  8#include <subcmd/parse-options.h>
  9#include "../util/header.h"
 10#include "bench.h"
 11#include "futex.h"
 12
 13#include <err.h>
 14#include <stdlib.h>
 15#include <sys/time.h>
 16#include <pthread.h>
 17
 18struct worker {
 19	int tid;
 20	u_int32_t *futex;
 21	pthread_t thread;
 22	unsigned long ops;
 23};
 24
 25static u_int32_t global_futex = 0;
 26static struct worker *worker;
 27static unsigned int nsecs = 10;
 28static bool silent = false, multi = false;
 29static bool done = false, fshared = false;
 30static unsigned int ncpus, nthreads = 0;
 31static int futex_flag = 0;
 32struct timeval start, end, runtime;
 33static pthread_mutex_t thread_lock;
 34static unsigned int threads_starting;
 35static struct stats throughput_stats;
 36static pthread_cond_t thread_parent, thread_worker;
 37
 38static const struct option options[] = {
 39	OPT_UINTEGER('t', "threads",  &nthreads, "Specify amount of threads"),
 40	OPT_UINTEGER('r', "runtime", &nsecs,     "Specify runtime (in seconds)"),
 41	OPT_BOOLEAN( 'M', "multi",   &multi,     "Use multiple futexes"),
 42	OPT_BOOLEAN( 's', "silent",  &silent,    "Silent mode: do not display data/details"),
 43	OPT_BOOLEAN( 'S', "shared",  &fshared,   "Use shared futexes instead of private ones"),
 44	OPT_END()
 45};
 46
 47static const char * const bench_futex_lock_pi_usage[] = {
 48	"perf bench futex requeue <options>",
 49	NULL
 50};
 51
 52static void print_summary(void)
 53{
 54	unsigned long avg = avg_stats(&throughput_stats);
 55	double stddev = stddev_stats(&throughput_stats);
 56
 57	printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
 58	       !silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg),
 59	       (int) runtime.tv_sec);
 60}
 61
 62static void toggle_done(int sig __maybe_unused,
 63			siginfo_t *info __maybe_unused,
 64			void *uc __maybe_unused)
 65{
 66	/* inform all threads that we're done for the day */
 67	done = true;
 68	gettimeofday(&end, NULL);
 69	timersub(&end, &start, &runtime);
 70}
 71
 72static void *workerfn(void *arg)
 73{
 74	struct worker *w = (struct worker *) arg;
 75
 76	pthread_mutex_lock(&thread_lock);
 77	threads_starting--;
 78	if (!threads_starting)
 79		pthread_cond_signal(&thread_parent);
 80	pthread_cond_wait(&thread_worker, &thread_lock);
 81	pthread_mutex_unlock(&thread_lock);
 82
 83	do {
 84		int ret;
 85	again:
 86		ret = futex_lock_pi(w->futex, NULL, 0, futex_flag);
 87
 88		if (ret) { /* handle lock acquisition */
 89			if (!silent)
 90				warn("thread %d: Could not lock pi-lock for %p (%d)",
 91				     w->tid, w->futex, ret);
 92			if (done)
 93				break;
 94
 95			goto again;
 96		}
 97
 98		usleep(1);
 99		ret = futex_unlock_pi(w->futex, futex_flag);
100		if (ret && !silent)
101			warn("thread %d: Could not unlock pi-lock for %p (%d)",
102			     w->tid, w->futex, ret);
103		w->ops++; /* account for thread's share of work */
104	}  while (!done);
105
106	return NULL;
107}
108
109static void create_threads(struct worker *w, pthread_attr_t thread_attr)
110{
111	cpu_set_t cpu;
112	unsigned int i;
113
114	threads_starting = nthreads;
115
116	for (i = 0; i < nthreads; i++) {
117		worker[i].tid = i;
118
119		if (multi) {
120			worker[i].futex = calloc(1, sizeof(u_int32_t));
121			if (!worker[i].futex)
122				err(EXIT_FAILURE, "calloc");
123		} else
124			worker[i].futex = &global_futex;
125
126		CPU_ZERO(&cpu);
127		CPU_SET(i % ncpus, &cpu);
128
129		if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu))
130			err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
131
132		if (pthread_create(&w[i].thread, &thread_attr, workerfn, &worker[i]))
133			err(EXIT_FAILURE, "pthread_create");
134	}
135}
136
137int bench_futex_lock_pi(int argc, const char **argv,
138			const char *prefix __maybe_unused)
139{
140	int ret = 0;
141	unsigned int i;
142	struct sigaction act;
143	pthread_attr_t thread_attr;
144
145	argc = parse_options(argc, argv, options, bench_futex_lock_pi_usage, 0);
146	if (argc)
147		goto err;
148
149	ncpus = sysconf(_SC_NPROCESSORS_ONLN);
150
151	sigfillset(&act.sa_mask);
152	act.sa_sigaction = toggle_done;
153	sigaction(SIGINT, &act, NULL);
154
155	if (!nthreads)
156		nthreads = ncpus;
157
158	worker = calloc(nthreads, sizeof(*worker));
159	if (!worker)
160		err(EXIT_FAILURE, "calloc");
161
162	if (!fshared)
163		futex_flag = FUTEX_PRIVATE_FLAG;
164
165	printf("Run summary [PID %d]: %d threads doing pi lock/unlock pairing for %d secs.\n\n",
166	       getpid(), nthreads, nsecs);
167
168	init_stats(&throughput_stats);
169	pthread_mutex_init(&thread_lock, NULL);
170	pthread_cond_init(&thread_parent, NULL);
171	pthread_cond_init(&thread_worker, NULL);
172
173	threads_starting = nthreads;
174	pthread_attr_init(&thread_attr);
175	gettimeofday(&start, NULL);
176
177	create_threads(worker, thread_attr);
178	pthread_attr_destroy(&thread_attr);
179
180	pthread_mutex_lock(&thread_lock);
181	while (threads_starting)
182		pthread_cond_wait(&thread_parent, &thread_lock);
183	pthread_cond_broadcast(&thread_worker);
184	pthread_mutex_unlock(&thread_lock);
185
186	sleep(nsecs);
187	toggle_done(0, NULL, NULL);
188
189	for (i = 0; i < nthreads; i++) {
190		ret = pthread_join(worker[i].thread, NULL);
191		if (ret)
192			err(EXIT_FAILURE, "pthread_join");
193	}
194
195	/* cleanup & report results */
196	pthread_cond_destroy(&thread_parent);
197	pthread_cond_destroy(&thread_worker);
198	pthread_mutex_destroy(&thread_lock);
199
200	for (i = 0; i < nthreads; i++) {
201		unsigned long t = worker[i].ops/runtime.tv_sec;
202
203		update_stats(&throughput_stats, t);
204		if (!silent)
205			printf("[thread %3d] futex: %p [ %ld ops/sec ]\n",
206			       worker[i].tid, worker[i].futex, t);
207
208		if (multi)
209			free(worker[i].futex);
210	}
211
212	print_summary();
213
214	free(worker);
215	return ret;
216err:
217	usage_with_options(bench_futex_lock_pi_usage, options);
218	exit(EXIT_FAILURE);
219}