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 <internal/cpumap.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
  26 struct worker {
  27         int tid;
  28         u_int32_t *futex;
  29         pthread_t thread;
  30         unsigned long ops;
  31 };
  32
  33 static u_int32_t global_futex = 0;
  34 static struct worker *worker;
  35 static unsigned int nsecs = 10;
  36 static bool silent = false, multi = false;
  37 static bool done = false, fshared = false;
  38 static unsigned int nthreads = 0;
  39 static int futex_flag = 0;
  40 struct timeval start, end, runtime;
  41 static pthread_mutex_t thread_lock;
  42 static unsigned int threads_starting;
  43 static struct stats throughput_stats;
  44 static pthread_cond_t thread_parent, thread_worker;
  45
  46 static const struct option options[] = {
  47         OPT_UINTEGER('t', "threads",  &nthreads, "Specify amount of threads"),
  48         OPT_UINTEGER('r', "runtime", &nsecs,     "Specify runtime (in seconds)"),
  49         OPT_BOOLEAN( 'M', "multi",   &multi,     "Use multiple futexes"),
  50         OPT_BOOLEAN( 's', "silent",  &silent,    "Silent mode: do not display data/details"),
  51         OPT_BOOLEAN( 'S', "shared",  &fshared,   "Use shared futexes instead of private ones"),
  52         OPT_END()
  53 };
  54
  55 static const char * const bench_futex_lock_pi_usage[] = {
  56         "perf bench futex lock-pi <options>",
  57         NULL
  58 };
  59
  60 static void print_summary(void)
  61 {
  62         unsigned long avg = avg_stats(&throughput_stats);
  63         double stddev = stddev_stats(&throughput_stats);
  64
  65         printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
  66                !silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg),
  67                (int) runtime.tv_sec);
  68 }
  69
  70 static void toggle_done(int sig __maybe_unused,
  71                         siginfo_t *info __maybe_unused,
  72                         void *uc __maybe_unused)
  73 {
  74         /* inform all threads that we're done for the day */
  75         done = true;
  76         gettimeofday(&end, NULL);
  77         timersub(&end, &start, &runtime);
  78 }
  79
  80 static void *workerfn(void *arg)
  81 {
  82         struct worker *w = (struct worker *) arg;
  83         unsigned long ops = w->ops;
  84
  85         pthread_mutex_lock(&thread_lock);
  86         threads_starting--;
  87         if (!threads_starting)
  88                 pthread_cond_signal(&thread_parent);
  89         pthread_cond_wait(&thread_worker, &thread_lock);
  90         pthread_mutex_unlock(&thread_lock);
  91
  92         do {
  93                 int ret;
  94         again:
  95                 ret = futex_lock_pi(w->futex, NULL, futex_flag);
  96
  97                 if (ret) { /* handle lock acquisition */
  98                         if (!silent)
  99                                 warn("thread %d: Could not lock pi-lock for %p (%d)",
 100                                      w->tid, w->futex, ret);
 101                         if (done)
 102                                 break;
 103
 104                         goto again;
 105                 }
 106
 107                 usleep(1);
 108                 ret = futex_unlock_pi(w->futex, futex_flag);
 109                 if (ret && !silent)
 110                         warn("thread %d: Could not unlock pi-lock for %p (%d)",
 111                              w->tid, w->futex, ret);
 112                 ops++; /* account for thread's share of work */
 113         }  while (!done);
 114
 115         w->ops = ops;
 116         return NULL;
 117 }
 118
 119 static void create_threads(struct worker *w, pthread_attr_t thread_attr,
 120                            struct perf_cpu_map *cpu)
 121 {
 122         cpu_set_t cpuset;
 123         unsigned int i;
 124
 125         threads_starting = nthreads;
 126
 127         for (i = 0; i < nthreads; i++) {
 128                 worker[i].tid = i;
 129
 130                 if (multi) {
 131                         worker[i].futex = calloc(1, sizeof(u_int32_t));
 132                         if (!worker[i].futex)
 133                                 err(EXIT_FAILURE, "calloc");
 134                 } else
 135                         worker[i].futex = &global_futex;
 136
 137                 CPU_ZERO(&cpuset);
 138                 CPU_SET(cpu->map[i % cpu->nr], &cpuset);
 139
 140                 if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset))
 141                         err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
 142
 143                 if (pthread_create(&w[i].thread, &thread_attr, workerfn, &worker[i]))
 144                         err(EXIT_FAILURE, "pthread_create");
 145         }
 146 }
 147
 148 int bench_futex_lock_pi(int argc, const char **argv)
 149 {
 150         int ret = 0;
 151         unsigned int i;
 152         struct sigaction act;
 153         pthread_attr_t thread_attr;
 154         struct perf_cpu_map *cpu;
 155
 156         argc = parse_options(argc, argv, options, bench_futex_lock_pi_usage, 0);
 157         if (argc)
 158                 goto err;
 159
 160         cpu = perf_cpu_map__new(NULL);
 161         if (!cpu)
 162                 err(EXIT_FAILURE, "calloc");
 163
 164         sigfillset(&act.sa_mask);
 165         act.sa_sigaction = toggle_done;
 166         sigaction(SIGINT, &act, NULL);
 167
 168         if (!nthreads)
 169                 nthreads = cpu->nr;
 170
 171         worker = calloc(nthreads, sizeof(*worker));
 172         if (!worker)
 173                 err(EXIT_FAILURE, "calloc");
 174
 175         if (!fshared)
 176                 futex_flag = FUTEX_PRIVATE_FLAG;
 177
 178         printf("Run summary [PID %d]: %d threads doing pi lock/unlock pairing for %d secs.\n\n",
 179                getpid(), nthreads, nsecs);
 180
 181         init_stats(&throughput_stats);
 182         pthread_mutex_init(&thread_lock, NULL);
 183         pthread_cond_init(&thread_parent, NULL);
 184         pthread_cond_init(&thread_worker, NULL);
 185
 186         threads_starting = nthreads;
 187         pthread_attr_init(&thread_attr);
 188         gettimeofday(&start, NULL);
 189
 190         create_threads(worker, thread_attr, cpu);
 191         pthread_attr_destroy(&thread_attr);
 192
 193         pthread_mutex_lock(&thread_lock);
 194         while (threads_starting)
 195                 pthread_cond_wait(&thread_parent, &thread_lock);
 196         pthread_cond_broadcast(&thread_worker);
 197         pthread_mutex_unlock(&thread_lock);
 198
 199         sleep(nsecs);
 200         toggle_done(0, NULL, NULL);
 201
 202         for (i = 0; i < nthreads; i++) {
 203                 ret = pthread_join(worker[i].thread, NULL);
 204                 if (ret)
 205                         err(EXIT_FAILURE, "pthread_join");
 206         }
 207
 208         /* cleanup & report results */
 209         pthread_cond_destroy(&thread_parent);
 210         pthread_cond_destroy(&thread_worker);
 211         pthread_mutex_destroy(&thread_lock);
 212
 213         for (i = 0; i < nthreads; i++) {
 214                 unsigned long t = worker[i].ops/runtime.tv_sec;
 215
 216                 update_stats(&throughput_stats, t);
 217                 if (!silent)
 218                         printf("[thread %3d] futex: %p [ %ld ops/sec ]\n",
 219                                worker[i].tid, worker[i].futex, t);
 220
 221                 if (multi)
 222                         zfree(&worker[i].futex);
 223         }
 224
 225         print_summary();
 226
 227         free(worker);
 228         return ret;
 229 err:
 230         usage_with_options(bench_futex_lock_pi_usage, options);
 231         exit(EXIT_FAILURE);
 232 }