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 <linux/zalloc.h>
  16 #include <errno.h>
  17 #include "bench.h"
  18 #include "futex.h"
  19 #include "cpumap.h"
  20
  21 #include <err.h>
  22 #include <stdlib.h>
  23 #include <sys/time.h>
  24
  25 struct worker {
  26         int tid;
  27         u_int32_t *futex;
  28         pthread_t thread;
  29         unsigned long ops;
  30 };
  31
  32 static u_int32_t global_futex = 0;
  33 static struct worker *worker;
  34 static unsigned int nsecs = 10;
  35 static bool silent = false, multi = false;
  36 static bool done = false, fshared = false;
  37 static unsigned int nthreads = 0;
  38 static int futex_flag = 0;
  39 struct timeval start, end, runtime;
  40 static pthread_mutex_t thread_lock;
  41 static unsigned int threads_starting;
  42 static struct stats throughput_stats;
  43 static pthread_cond_t thread_parent, thread_worker;
  44
  45 static const struct option options[] = {
  46         OPT_UINTEGER('t', "threads",  &nthreads, "Specify amount of threads"),
  47         OPT_UINTEGER('r', "runtime", &nsecs,     "Specify runtime (in seconds)"),
  48         OPT_BOOLEAN( 'M', "multi",   &multi,     "Use multiple futexes"),
  49         OPT_BOOLEAN( 's', "silent",  &silent,    "Silent mode: do not display data/details"),
  50         OPT_BOOLEAN( 'S', "shared",  &fshared,   "Use shared futexes instead of private ones"),
  51         OPT_END()
  52 };
  53
  54 static const char * const bench_futex_lock_pi_usage[] = {
  55         "perf bench futex lock-pi <options>",
  56         NULL
  57 };
  58
  59 static void print_summary(void)
  60 {
  61         unsigned long avg = avg_stats(&throughput_stats);
  62         double stddev = stddev_stats(&throughput_stats);
  63
  64         printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
  65                !silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg),
  66                (int) runtime.tv_sec);
  67 }
  68
  69 static void toggle_done(int sig __maybe_unused,
  70                         siginfo_t *info __maybe_unused,
  71                         void *uc __maybe_unused)
  72 {
  73         /* inform all threads that we're done for the day */
  74         done = true;
  75         gettimeofday(&end, NULL);
  76         timersub(&end, &start, &runtime);
  77 }
  78
  79 static void *workerfn(void *arg)
  80 {
  81         struct worker *w = (struct worker *) arg;
  82         unsigned long ops = w->ops;
  83
  84         pthread_mutex_lock(&thread_lock);
  85         threads_starting--;
  86         if (!threads_starting)
  87                 pthread_cond_signal(&thread_parent);
  88         pthread_cond_wait(&thread_worker, &thread_lock);
  89         pthread_mutex_unlock(&thread_lock);
  90
  91         do {
  92                 int ret;
  93         again:
  94                 ret = futex_lock_pi(w->futex, NULL, futex_flag);
  95
  96                 if (ret) { /* handle lock acquisition */
  97                         if (!silent)
  98                                 warn("thread %d: Could not lock pi-lock for %p (%d)",
  99                                      w->tid, w->futex, ret);
 100                         if (done)
 101                                 break;
 102
 103                         goto again;
 104                 }
 105
 106                 usleep(1);
 107                 ret = futex_unlock_pi(w->futex, futex_flag);
 108                 if (ret && !silent)
 109                         warn("thread %d: Could not unlock pi-lock for %p (%d)",
 110                              w->tid, w->futex, ret);
 111                 ops++; /* account for thread's share of work */
 112         }  while (!done);
 113
 114         w->ops = ops;
 115         return NULL;
 116 }
 117
 118 static void create_threads(struct worker *w, pthread_attr_t thread_attr,
 119                            struct cpu_map *cpu)
 120 {
 121         cpu_set_t cpuset;
 122         unsigned int i;
 123
 124         threads_starting = nthreads;
 125
 126         for (i = 0; i < nthreads; i++) {
 127                 worker[i].tid = i;
 128
 129                 if (multi) {
 130                         worker[i].futex = calloc(1, sizeof(u_int32_t));
 131                         if (!worker[i].futex)
 132                                 err(EXIT_FAILURE, "calloc");
 133                 } else
 134                         worker[i].futex = &global_futex;
 135
 136                 CPU_ZERO(&cpuset);
 137                 CPU_SET(cpu->map[i % cpu->nr], &cpuset);
 138
 139                 if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset))
 140                         err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
 141
 142                 if (pthread_create(&w[i].thread, &thread_attr, workerfn, &worker[i]))
 143                         err(EXIT_FAILURE, "pthread_create");
 144         }
 145 }
 146
 147 int bench_futex_lock_pi(int argc, const char **argv)
 148 {
 149         int ret = 0;
 150         unsigned int i;
 151         struct sigaction act;
 152         pthread_attr_t thread_attr;
 153         struct cpu_map *cpu;
 154
 155         argc = parse_options(argc, argv, options, bench_futex_lock_pi_usage, 0);
 156         if (argc)
 157                 goto err;
 158
 159         cpu = cpu_map__new(NULL);
 160         if (!cpu)
 161                 err(EXIT_FAILURE, "calloc");
 162
 163         sigfillset(&act.sa_mask);
 164         act.sa_sigaction = toggle_done;
 165         sigaction(SIGINT, &act, NULL);
 166
 167         if (!nthreads)
 168                 nthreads = cpu->nr;
 169
 170         worker = calloc(nthreads, sizeof(*worker));
 171         if (!worker)
 172                 err(EXIT_FAILURE, "calloc");
 173
 174         if (!fshared)
 175                 futex_flag = FUTEX_PRIVATE_FLAG;
 176
 177         printf("Run summary [PID %d]: %d threads doing pi lock/unlock pairing for %d secs.\n\n",
 178                getpid(), nthreads, nsecs);
 179
 180         init_stats(&throughput_stats);
 181         pthread_mutex_init(&thread_lock, NULL);
 182         pthread_cond_init(&thread_parent, NULL);
 183         pthread_cond_init(&thread_worker, NULL);
 184
 185         threads_starting = nthreads;
 186         pthread_attr_init(&thread_attr);
 187         gettimeofday(&start, NULL);
 188
 189         create_threads(worker, thread_attr, cpu);
 190         pthread_attr_destroy(&thread_attr);
 191
 192         pthread_mutex_lock(&thread_lock);
 193         while (threads_starting)
 194                 pthread_cond_wait(&thread_parent, &thread_lock);
 195         pthread_cond_broadcast(&thread_worker);
 196         pthread_mutex_unlock(&thread_lock);
 197
 198         sleep(nsecs);
 199         toggle_done(0, NULL, NULL);
 200
 201         for (i = 0; i < nthreads; i++) {
 202                 ret = pthread_join(worker[i].thread, NULL);
 203                 if (ret)
 204                         err(EXIT_FAILURE, "pthread_join");
 205         }
 206
 207         /* cleanup & report results */
 208         pthread_cond_destroy(&thread_parent);
 209         pthread_cond_destroy(&thread_worker);
 210         pthread_mutex_destroy(&thread_lock);
 211
 212         for (i = 0; i < nthreads; i++) {
 213                 unsigned long t = worker[i].ops/runtime.tv_sec;
 214
 215                 update_stats(&throughput_stats, t);
 216                 if (!silent)
 217                         printf("[thread %3d] futex: %p [ %ld ops/sec ]\n",
 218                                worker[i].tid, worker[i].futex, t);
 219
 220                 if (multi)
 221                         zfree(&worker[i].futex);
 222         }
 223
 224         print_summary();
 225
 226         free(worker);
 227         return ret;
 228 err:
 229         usage_with_options(bench_futex_lock_pi_usage, options);
 230         exit(EXIT_FAILURE);
 231 }