futex-lock-pi.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2015 Davidlohr Bueso.
  4 */
  5
  6/* For the CLR_() macros */
  7#include <string.h>
  8#include <pthread.h>
  9
 10#include <signal.h>
 11#include "../util/mutex.h"
 12#include "../util/stat.h"
 13#include <subcmd/parse-options.h>
 14#include <linux/compiler.h>
 15#include <linux/kernel.h>
 16#include <linux/zalloc.h>
 17#include <errno.h>
 18#include <perf/cpumap.h>
 19#include "bench.h"
 20#include "futex.h"
 21
 22#include <err.h>
 23#include <stdlib.h>
 24#include <sys/time.h>
 25#include <sys/mman.h>
 26
 27struct worker {
 28	int tid;
 29	u_int32_t *futex;
 30	pthread_t thread;
 31	unsigned long ops;
 32};
 33
 34static u_int32_t global_futex = 0;
 35static struct worker *worker;
 36static bool done = false;
 37static int futex_flag = 0;
 38static struct mutex thread_lock;
 39static unsigned int threads_starting;
 40static struct stats throughput_stats;
 41static struct cond thread_parent, thread_worker;
 42
 43static struct bench_futex_parameters params = {
 44	.nbuckets = -1,
 45	.runtime  = 10,
 46};
 47
 48static const struct option options[] = {
 49	OPT_INTEGER( 'b', "buckets", &params.nbuckets, "Specify amount of hash buckets"),
 50	OPT_UINTEGER('t', "threads", &params.nthreads, "Specify amount of threads"),
 51	OPT_UINTEGER('r', "runtime", &params.runtime, "Specify runtime (in seconds)"),
 52	OPT_BOOLEAN( 'M', "multi",   &params.multi, "Use multiple futexes"),
 53	OPT_BOOLEAN( 's', "silent",  &params.silent, "Silent mode: do not display data/details"),
 54	OPT_BOOLEAN( 'S', "shared",  &params.fshared, "Use shared futexes instead of private ones"),
 55	OPT_BOOLEAN( 'm', "mlockall", &params.mlockall, "Lock all current and future memory"),
 56	OPT_END()
 57};
 58
 59static const char * const bench_futex_lock_pi_usage[] = {
 60	"perf bench futex lock-pi <options>",
 61	NULL
 62};
 63
 64static void print_summary(void)
 65{
 66	unsigned long avg = avg_stats(&throughput_stats);
 67	double stddev = stddev_stats(&throughput_stats);
 68
 69	printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
 70	       !params.silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg),
 71	       (int)bench__runtime.tv_sec);
 72	futex_print_nbuckets(&params);
 73}
 74
 75static void toggle_done(int sig __maybe_unused,
 76			siginfo_t *info __maybe_unused,
 77			void *uc __maybe_unused)
 78{
 79	/* inform all threads that we're done for the day */
 80	done = true;
 81	gettimeofday(&bench__end, NULL);
 82	timersub(&bench__end, &bench__start, &bench__runtime);
 83}
 84
 85static void *workerfn(void *arg)
 86{
 87	struct worker *w = (struct worker *) arg;
 88	unsigned long ops = w->ops;
 89
 90	mutex_lock(&thread_lock);
 91	threads_starting--;
 92	if (!threads_starting)
 93		cond_signal(&thread_parent);
 94	cond_wait(&thread_worker, &thread_lock);
 95	mutex_unlock(&thread_lock);
 96
 97	do {
 98		int ret;
 99	again:
100		ret = futex_lock_pi(w->futex, NULL, futex_flag);
101
102		if (ret) { /* handle lock acquisition */
103			if (!params.silent)
104				warn("thread %d: Could not lock pi-lock for %p (%d)",
105				     w->tid, w->futex, ret);
106			if (done)
107				break;
108
109			goto again;
110		}
111
112		usleep(1);
113		ret = futex_unlock_pi(w->futex, futex_flag);
114		if (ret && !params.silent)
115			warn("thread %d: Could not unlock pi-lock for %p (%d)",
116			     w->tid, w->futex, ret);
117		ops++; /* account for thread's share of work */
118	}  while (!done);
119
120	w->ops = ops;
121	return NULL;
122}
123
124static void create_threads(struct worker *w, struct perf_cpu_map *cpu)
125{
126	cpu_set_t *cpuset;
127	unsigned int i;
128	int nrcpus =  cpu__max_cpu().cpu;
129	size_t size;
130
131	threads_starting = params.nthreads;
132
133	cpuset = CPU_ALLOC(nrcpus);
134	BUG_ON(!cpuset);
135	size = CPU_ALLOC_SIZE(nrcpus);
136
137	for (i = 0; i < params.nthreads; i++) {
138		pthread_attr_t thread_attr;
139
140		pthread_attr_init(&thread_attr);
141		worker[i].tid = i;
142
143		if (params.multi) {
144			worker[i].futex = calloc(1, sizeof(u_int32_t));
145			if (!worker[i].futex)
146				err(EXIT_FAILURE, "calloc");
147		} else
148			worker[i].futex = &global_futex;
149
150		CPU_ZERO_S(size, cpuset);
151		CPU_SET_S(perf_cpu_map__cpu(cpu, i % perf_cpu_map__nr(cpu)).cpu, size, cpuset);
152
153		if (pthread_attr_setaffinity_np(&thread_attr, size, cpuset)) {
154			CPU_FREE(cpuset);
155			err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
156		}
157
158		if (pthread_create(&w[i].thread, &thread_attr, workerfn, &worker[i])) {
159			CPU_FREE(cpuset);
160			err(EXIT_FAILURE, "pthread_create");
161		}
162		pthread_attr_destroy(&thread_attr);
163	}
164	CPU_FREE(cpuset);
165}
166
167int bench_futex_lock_pi(int argc, const char **argv)
168{
169	int ret = 0;
170	unsigned int i;
171	struct sigaction act;
172	struct perf_cpu_map *cpu;
173
174	argc = parse_options(argc, argv, options, bench_futex_lock_pi_usage, 0);
175	if (argc)
176		goto err;
177
178	cpu = perf_cpu_map__new_online_cpus();
179	if (!cpu)
180		err(EXIT_FAILURE, "calloc");
181
182	memset(&act, 0, sizeof(act));
183	sigfillset(&act.sa_mask);
184	act.sa_sigaction = toggle_done;
185	sigaction(SIGINT, &act, NULL);
186
187	if (params.mlockall) {
188		if (mlockall(MCL_CURRENT | MCL_FUTURE))
189			err(EXIT_FAILURE, "mlockall");
190	}
191
192	if (!params.nthreads)
193		params.nthreads = perf_cpu_map__nr(cpu);
194
195	worker = calloc(params.nthreads, sizeof(*worker));
196	if (!worker)
197		err(EXIT_FAILURE, "calloc");
198
199	if (!params.fshared)
200		futex_flag = FUTEX_PRIVATE_FLAG;
201
202	printf("Run summary [PID %d]: %d threads doing pi lock/unlock pairing for %d secs.\n\n",
203	       getpid(), params.nthreads, params.runtime);
204
205	init_stats(&throughput_stats);
206	mutex_init(&thread_lock);
207	cond_init(&thread_parent);
208	cond_init(&thread_worker);
209	futex_set_nbuckets_param(&params);
210
211	threads_starting = params.nthreads;
212	gettimeofday(&bench__start, NULL);
213
214	create_threads(worker, cpu);
215
216	mutex_lock(&thread_lock);
217	while (threads_starting)
218		cond_wait(&thread_parent, &thread_lock);
219	cond_broadcast(&thread_worker);
220	mutex_unlock(&thread_lock);
221
222	sleep(params.runtime);
223	toggle_done(0, NULL, NULL);
224
225	for (i = 0; i < params.nthreads; i++) {
226		ret = pthread_join(worker[i].thread, NULL);
227		if (ret)
228			err(EXIT_FAILURE, "pthread_join");
229	}
230
231	/* cleanup & report results */
232	cond_destroy(&thread_parent);
233	cond_destroy(&thread_worker);
234	mutex_destroy(&thread_lock);
235
236	for (i = 0; i < params.nthreads; i++) {
237		unsigned long t = bench__runtime.tv_sec > 0 ?
238			worker[i].ops / bench__runtime.tv_sec : 0;
239
240		update_stats(&throughput_stats, t);
241		if (!params.silent)
242			printf("[thread %3d] futex: %p [ %ld ops/sec ]\n",
243			       worker[i].tid, worker[i].futex, t);
244
245		if (params.multi)
246			zfree(&worker[i].futex);
247	}
248
249	print_summary();
250
251	free(worker);
252	perf_cpu_map__put(cpu);
253	return ret;
254err:
255	usage_with_options(bench_futex_lock_pi_usage, options);
256	exit(EXIT_FAILURE);
257}