tools/perf/bench/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/stat.h"
  12 #include <subcmd/parse-options.h>
  13 #include <linux/compiler.h>
  14 #include <linux/kernel.h>
  15 #include <errno.h>
  16 #include "bench.h"
  17 #include "futex.h"
  18 #include "cpumap.h"
  19
  20 #include <err.h>
  21 #include <stdlib.h>
  22 #include <sys/time.h>
  23
  24 struct worker {
  25         int tid;
  26         u_int32_t *futex;
  27         pthread_t thread;
  28         unsigned long ops;
  29 };
  30
  31 static u_int32_t global_futex = 0;
  32 static struct worker *worker;
  33 static unsigned int nsecs = 10;
  34 static bool silent = false, multi = false;
  35 static bool done = false, fshared = false;
  36 static unsigned int nthreads = 0;
  37 static int futex_flag = 0;
  38 struct timeval start, end, runtime;
  39 static pthread_mutex_t thread_lock;
  40 static unsigned int threads_starting;
  41 static struct stats throughput_stats;
  42 static pthread_cond_t thread_parent, thread_worker;
  43
  44 static const struct option options[] = {
  45         OPT_UINTEGER('t', "threads",  &nthreads, "Specify amount of threads"),
  46         OPT_UINTEGER('r', "runtime", &nsecs,     "Specify runtime (in seconds)"),
  47         OPT_BOOLEAN( 'M', "multi",   &multi,     "Use multiple futexes"),
  48         OPT_BOOLEAN( 's', "silent",  &silent,    "Silent mode: do not display data/details"),
  49         OPT_BOOLEAN( 'S', "shared",  &fshared,   "Use shared futexes instead of private ones"),
  50         OPT_END()
  51 };
  52
  53 static const char * const bench_futex_lock_pi_usage[] = {
  54         "perf bench futex lock-pi <options>",
  55         NULL
  56 };
  57
  58 static void print_summary(void)
  59 {
  60         unsigned long avg = avg_stats(&throughput_stats);
  61         double stddev = stddev_stats(&throughput_stats);
  62
  63         printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
  64                !silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg),
  65                (int) runtime.tv_sec);
  66 }
  67
  68 static void toggle_done(int sig __maybe_unused,
  69                         siginfo_t *info __maybe_unused,
  70                         void *uc __maybe_unused)
  71 {
  72         /* inform all threads that we're done for the day */
  73         done = true;
  74         gettimeofday(&end, NULL);
  75         timersub(&end, &start, &runtime);
  76 }
  77
  78 static void *workerfn(void *arg)
  79 {
  80         struct worker *w = (struct worker *) arg;
  81         unsigned long ops = w->ops;
  82
  83         pthread_mutex_lock(&thread_lock);
  84         threads_starting--;
  85         if (!threads_starting)
  86                 pthread_cond_signal(&thread_parent);
  87         pthread_cond_wait(&thread_worker, &thread_lock);
  88         pthread_mutex_unlock(&thread_lock);
  89
  90         do {
  91                 int ret;
  92         again:
  93                 ret = futex_lock_pi(w->futex, NULL, futex_flag);
  94
  95                 if (ret) { /* handle lock acquisition */
  96                         if (!silent)
  97                                 warn("thread %d: Could not lock pi-lock for %p (%d)",
  98                                      w->tid, w->futex, ret);
  99                         if (done)
 100                                 break;
 101
 102                         goto again;
 103                 }
 104
 105                 usleep(1);
 106                 ret = futex_unlock_pi(w->futex, futex_flag);
 107                 if (ret && !silent)
 108                         warn("thread %d: Could not unlock pi-lock for %p (%d)",
 109                              w->tid, w->futex, ret);
 110                 ops++; /* account for thread's share of work */
 111         }  while (!done);
 112
 113         w->ops = ops;
 114         return NULL;
 115 }
 116
 117 static void create_threads(struct worker *w, pthread_attr_t thread_attr,
 118                            struct cpu_map *cpu)
 119 {
 120         cpu_set_t cpuset;
 121         unsigned int i;
 122
 123         threads_starting = nthreads;
 124
 125         for (i = 0; i < nthreads; i++) {
 126                 worker[i].tid = i;
 127
 128                 if (multi) {
 129                         worker[i].futex = calloc(1, sizeof(u_int32_t));
 130                         if (!worker[i].futex)
 131                                 err(EXIT_FAILURE, "calloc");
 132                 } else
 133                         worker[i].futex = &global_futex;
 134
 135                 CPU_ZERO(&cpuset);
 136                 CPU_SET(cpu->map[i % cpu->nr], &cpuset);
 137
 138                 if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset))
 139                         err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
 140
 141                 if (pthread_create(&w[i].thread, &thread_attr, workerfn, &worker[i]))
 142                         err(EXIT_FAILURE, "pthread_create");
 143         }
 144 }
 145
 146 int bench_futex_lock_pi(int argc, const char **argv)
 147 {
 148         int ret = 0;
 149         unsigned int i;
 150         struct sigaction act;
 151         pthread_attr_t thread_attr;
 152         struct cpu_map *cpu;
 153
 154         argc = parse_options(argc, argv, options, bench_futex_lock_pi_usage, 0);
 155         if (argc)
 156                 goto err;
 157
 158         cpu = cpu_map__new(NULL);
 159         if (!cpu)
 160                 err(EXIT_FAILURE, "calloc");
 161
 162         sigfillset(&act.sa_mask);
 163         act.sa_sigaction = toggle_done;
 164         sigaction(SIGINT, &act, NULL);
 165
 166         if (!nthreads)
 167                 nthreads = cpu->nr;
 168
 169         worker = calloc(nthreads, sizeof(*worker));
 170         if (!worker)
 171                 err(EXIT_FAILURE, "calloc");
 172
 173         if (!fshared)
 174                 futex_flag = FUTEX_PRIVATE_FLAG;
 175
 176         printf("Run summary [PID %d]: %d threads doing pi lock/unlock pairing for %d secs.\n\n",
 177                getpid(), nthreads, nsecs);
 178
 179         init_stats(&throughput_stats);
 180         pthread_mutex_init(&thread_lock, NULL);
 181         pthread_cond_init(&thread_parent, NULL);
 182         pthread_cond_init(&thread_worker, NULL);
 183
 184         threads_starting = nthreads;
 185         pthread_attr_init(&thread_attr);
 186         gettimeofday(&start, NULL);
 187
 188         create_threads(worker, thread_attr, cpu);
 189         pthread_attr_destroy(&thread_attr);
 190
 191         pthread_mutex_lock(&thread_lock);
 192         while (threads_starting)
 193                 pthread_cond_wait(&thread_parent, &thread_lock);
 194         pthread_cond_broadcast(&thread_worker);
 195         pthread_mutex_unlock(&thread_lock);
 196
 197         sleep(nsecs);
 198         toggle_done(0, NULL, NULL);
 199
 200         for (i = 0; i < nthreads; i++) {
 201                 ret = pthread_join(worker[i].thread, NULL);
 202                 if (ret)
 203                         err(EXIT_FAILURE, "pthread_join");
 204         }
 205
 206         /* cleanup & report results */
 207         pthread_cond_destroy(&thread_parent);
 208         pthread_cond_destroy(&thread_worker);
 209         pthread_mutex_destroy(&thread_lock);
 210
 211         for (i = 0; i < nthreads; i++) {
 212                 unsigned long t = worker[i].ops/runtime.tv_sec;
 213
 214                 update_stats(&throughput_stats, t);
 215                 if (!silent)
 216                         printf("[thread %3d] futex: %p [ %ld ops/sec ]\n",
 217                                worker[i].tid, worker[i].futex, t);
 218
 219                 if (multi)
 220                         free(worker[i].futex);
 221         }
 222
 223         print_summary();
 224
 225         free(worker);
 226         return ret;
 227 err:
 228         usage_with_options(bench_futex_lock_pi_usage, options);
 229         exit(EXIT_FAILURE);
 230 }