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