kernel/tools/perf/bench/futex-lock-pi.c

   1 /*
   2  * Copyright (C) 2015 Davidlohr Bueso.
   3  */
   4
   5 #include "../perf.h"
   6 #include "../util/util.h"
   7 #include "../util/stat.h"
   8 #include "../util/parse-options.h"
   9 #include "../util/header.h"
  10 #include "bench.h"
  11 #include "futex.h"
  12
  13 #include <err.h>
  14 #include <stdlib.h>
  15 #include <sys/time.h>
  16 #include <pthread.h>
  17
  18 struct worker {
  19         int tid;
  20         u_int32_t *futex;
  21         pthread_t thread;
  22         unsigned long ops;
  23 };
  24
  25 static u_int32_t global_futex = 0;
  26 static struct worker *worker;
  27 static unsigned int nsecs = 10;
  28 static bool silent = false, multi = false;
  29 static bool done = false, fshared = false;
  30 static unsigned int ncpus, nthreads = 0;
  31 static int futex_flag = 0;
  32 struct timeval start, end, runtime;
  33 static pthread_mutex_t thread_lock;
  34 static unsigned int threads_starting;
  35 static struct stats throughput_stats;
  36 static pthread_cond_t thread_parent, thread_worker;
  37
  38 static const struct option options[] = {
  39         OPT_UINTEGER('t', "threads",  &nthreads, "Specify amount of threads"),
  40         OPT_UINTEGER('r', "runtime", &nsecs,     "Specify runtime (in seconds)"),
  41         OPT_BOOLEAN( 'M', "multi",   &multi,     "Use multiple futexes"),
  42         OPT_BOOLEAN( 's', "silent",  &silent,    "Silent mode: do not display data/details"),
  43         OPT_BOOLEAN( 'S', "shared",  &fshared,   "Use shared futexes instead of private ones"),
  44         OPT_END()
  45 };
  46
  47 static const char * const bench_futex_lock_pi_usage[] = {
  48         "perf bench futex requeue <options>",
  49         NULL
  50 };
  51
  52 static void print_summary(void)
  53 {
  54         unsigned long avg = avg_stats(&throughput_stats);
  55         double stddev = stddev_stats(&throughput_stats);
  56
  57         printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
  58                !silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg),
  59                (int) runtime.tv_sec);
  60 }
  61
  62 static void toggle_done(int sig __maybe_unused,
  63                         siginfo_t *info __maybe_unused,
  64                         void *uc __maybe_unused)
  65 {
  66         /* inform all threads that we're done for the day */
  67         done = true;
  68         gettimeofday(&end, NULL);
  69         timersub(&end, &start, &runtime);
  70 }
  71
  72 static void *workerfn(void *arg)
  73 {
  74         struct worker *w = (struct worker *) arg;
  75
  76         pthread_mutex_lock(&thread_lock);
  77         threads_starting--;
  78         if (!threads_starting)
  79                 pthread_cond_signal(&thread_parent);
  80         pthread_cond_wait(&thread_worker, &thread_lock);
  81         pthread_mutex_unlock(&thread_lock);
  82
  83         do {
  84                 int ret;
  85         again:
  86                 ret = futex_lock_pi(w->futex, NULL, 0, futex_flag);
  87
  88                 if (ret) { /* handle lock acquisition */
  89                         if (!silent)
  90                                 warn("thread %d: Could not lock pi-lock for %p (%d)",
  91                                      w->tid, w->futex, ret);
  92                         if (done)
  93                                 break;
  94
  95                         goto again;
  96                 }
  97
  98                 usleep(1);
  99                 ret = futex_unlock_pi(w->futex, futex_flag);
 100                 if (ret && !silent)
 101                         warn("thread %d: Could not unlock pi-lock for %p (%d)",
 102                              w->tid, w->futex, ret);
 103                 w->ops++; /* account for thread's share of work */
 104         }  while (!done);
 105
 106         return NULL;
 107 }
 108
 109 static void create_threads(struct worker *w, pthread_attr_t thread_attr)
 110 {
 111         cpu_set_t cpu;
 112         unsigned int i;
 113
 114         threads_starting = nthreads;
 115
 116         for (i = 0; i < nthreads; i++) {
 117                 worker[i].tid = i;
 118
 119                 if (multi) {
 120                         worker[i].futex = calloc(1, sizeof(u_int32_t));
 121                         if (!worker[i].futex)
 122                                 err(EXIT_FAILURE, "calloc");
 123                 } else
 124                         worker[i].futex = &global_futex;
 125
 126                 CPU_ZERO(&cpu);
 127                 CPU_SET(i % ncpus, &cpu);
 128
 129                 if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu))
 130                         err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
 131
 132                 if (pthread_create(&w[i].thread, &thread_attr, workerfn, &worker[i]))
 133                         err(EXIT_FAILURE, "pthread_create");
 134         }
 135 }
 136
 137 int bench_futex_lock_pi(int argc, const char **argv,
 138                         const char *prefix __maybe_unused)
 139 {
 140         int ret = 0;
 141         unsigned int i;
 142         struct sigaction act;
 143         pthread_attr_t thread_attr;
 144
 145         argc = parse_options(argc, argv, options, bench_futex_lock_pi_usage, 0);
 146         if (argc)
 147                 goto err;
 148
 149         ncpus = sysconf(_SC_NPROCESSORS_ONLN);
 150
 151         sigfillset(&act.sa_mask);
 152         act.sa_sigaction = toggle_done;
 153         sigaction(SIGINT, &act, NULL);
 154
 155         if (!nthreads)
 156                 nthreads = ncpus;
 157
 158         worker = calloc(nthreads, sizeof(*worker));
 159         if (!worker)
 160                 err(EXIT_FAILURE, "calloc");
 161
 162         if (!fshared)
 163                 futex_flag = FUTEX_PRIVATE_FLAG;
 164
 165         printf("Run summary [PID %d]: %d threads doing pi lock/unlock pairing for %d secs.\n\n",
 166                getpid(), nthreads, nsecs);
 167
 168         init_stats(&throughput_stats);
 169         pthread_mutex_init(&thread_lock, NULL);
 170         pthread_cond_init(&thread_parent, NULL);
 171         pthread_cond_init(&thread_worker, NULL);
 172
 173         threads_starting = nthreads;
 174         pthread_attr_init(&thread_attr);
 175         gettimeofday(&start, NULL);
 176
 177         create_threads(worker, thread_attr);
 178         pthread_attr_destroy(&thread_attr);
 179
 180         pthread_mutex_lock(&thread_lock);
 181         while (threads_starting)
 182                 pthread_cond_wait(&thread_parent, &thread_lock);
 183         pthread_cond_broadcast(&thread_worker);
 184         pthread_mutex_unlock(&thread_lock);
 185
 186         sleep(nsecs);
 187         toggle_done(0, NULL, NULL);
 188
 189         for (i = 0; i < nthreads; i++) {
 190                 ret = pthread_join(worker[i].thread, NULL);
 191                 if (ret)
 192                         err(EXIT_FAILURE, "pthread_join");
 193         }
 194
 195         /* cleanup & report results */
 196         pthread_cond_destroy(&thread_parent);
 197         pthread_cond_destroy(&thread_worker);
 198         pthread_mutex_destroy(&thread_lock);
 199
 200         for (i = 0; i < nthreads; i++) {
 201                 unsigned long t = worker[i].ops/runtime.tv_sec;
 202
 203                 update_stats(&throughput_stats, t);
 204                 if (!silent)
 205                         printf("[thread %3d] futex: %p [ %ld ops/sec ]\n",
 206                                worker[i].tid, worker[i].futex, t);
 207
 208                 if (multi)
 209                         free(worker[i].futex);
 210         }
 211
 212         print_summary();
 213
 214         free(worker);
 215         return ret;
 216 err:
 217         usage_with_options(bench_futex_lock_pi_usage, options);
 218         exit(EXIT_FAILURE);
 219 }