tools/perf/bench/futex-hash.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2013  Davidlohr Bueso <davidlohr@hp.com>
   4  *
   5  * futex-hash: Stress the hell out of the Linux kernel futex uaddr hashing.
   6  *
   7  * This program is particularly useful for measuring the kernel's futex hash
   8  * table/function implementation. In order for it to make sense, use with as
   9  * many threads and futexes as possible.
  10  */
  11
  12 /* For the CLR_() macros */
  13 #include <string.h>
  14 #include <pthread.h>
  15
  16 #include <errno.h>
  17 #include <signal.h>
  18 #include <stdlib.h>
  19 #include <linux/compiler.h>
  20 #include <linux/kernel.h>
  21 #include <linux/zalloc.h>
  22 #include <sys/time.h>
  23 #include <sys/mman.h>
  24 #include <perf/cpumap.h>
  25
  26 #include "../util/mutex.h"
  27 #include "../util/stat.h"
  28 #include <subcmd/parse-options.h>
  29 #include "bench.h"
  30 #include "futex.h"
  31
  32 #include <err.h>
  33
  34 static bool done = false;
  35 static int futex_flag = 0;
  36
  37 struct timeval bench__start, bench__end, bench__runtime;
  38 static struct mutex thread_lock;
  39 static unsigned int threads_starting;
  40 static struct stats throughput_stats;
  41 static struct cond thread_parent, thread_worker;
  42
  43 struct worker {
  44         int tid;
  45         u_int32_t *futex;
  46         pthread_t thread;
  47         unsigned long ops;
  48 };
  49
  50 static struct bench_futex_parameters params = {
  51         .nfutexes = 1024,
  52         .runtime  = 10,
  53 };
  54
  55 static const struct option options[] = {
  56         OPT_UINTEGER('t', "threads", &params.nthreads, "Specify amount of threads"),
  57         OPT_UINTEGER('r', "runtime", &params.runtime, "Specify runtime (in seconds)"),
  58         OPT_UINTEGER('f', "futexes", &params.nfutexes, "Specify amount of futexes per threads"),
  59         OPT_BOOLEAN( 's', "silent",  &params.silent, "Silent mode: do not display data/details"),
  60         OPT_BOOLEAN( 'S', "shared",  &params.fshared, "Use shared futexes instead of private ones"),
  61         OPT_BOOLEAN( 'm', "mlockall", &params.mlockall, "Lock all current and future memory"),
  62         OPT_END()
  63 };
  64
  65 static const char * const bench_futex_hash_usage[] = {
  66         "perf bench futex hash <options>",
  67         NULL
  68 };
  69
  70 static void *workerfn(void *arg)
  71 {
  72         int ret;
  73         struct worker *w = (struct worker *) arg;
  74         unsigned int i;
  75         unsigned long ops = w->ops; /* avoid cacheline bouncing */
  76
  77         mutex_lock(&thread_lock);
  78         threads_starting--;
  79         if (!threads_starting)
  80                 cond_signal(&thread_parent);
  81         cond_wait(&thread_worker, &thread_lock);
  82         mutex_unlock(&thread_lock);
  83
  84         do {
  85                 for (i = 0; i < params.nfutexes; i++, ops++) {
  86                         /*
  87                          * We want the futex calls to fail in order to stress
  88                          * the hashing of uaddr and not measure other steps,
  89                          * such as internal waitqueue handling, thus enlarging
  90                          * the critical region protected by hb->lock.
  91                          */
  92                         ret = futex_wait(&w->futex[i], 1234, NULL, futex_flag);
  93                         if (!params.silent &&
  94                             (!ret || errno != EAGAIN || errno != EWOULDBLOCK))
  95                                 warn("Non-expected futex return call");
  96                 }
  97         }  while (!done);
  98
  99         w->ops = ops;
 100         return NULL;
 101 }
 102
 103 static void toggle_done(int sig __maybe_unused,
 104                         siginfo_t *info __maybe_unused,
 105                         void *uc __maybe_unused)
 106 {
 107         /* inform all threads that we're done for the day */
 108         done = true;
 109         gettimeofday(&bench__end, NULL);
 110         timersub(&bench__end, &bench__start, &bench__runtime);
 111 }
 112
 113 static void print_summary(void)
 114 {
 115         unsigned long avg = avg_stats(&throughput_stats);
 116         double stddev = stddev_stats(&throughput_stats);
 117
 118         printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
 119                !params.silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg),
 120                (int)bench__runtime.tv_sec);
 121 }
 122
 123 int bench_futex_hash(int argc, const char **argv)
 124 {
 125         int ret = 0;
 126         cpu_set_t *cpuset;
 127         struct sigaction act;
 128         unsigned int i;
 129         pthread_attr_t thread_attr;
 130         struct worker *worker = NULL;
 131         struct perf_cpu_map *cpu;
 132         int nrcpus;
 133         size_t size;
 134
 135         argc = parse_options(argc, argv, options, bench_futex_hash_usage, 0);
 136         if (argc) {
 137                 usage_with_options(bench_futex_hash_usage, options);
 138                 exit(EXIT_FAILURE);
 139         }
 140
 141         cpu = perf_cpu_map__new_online_cpus();
 142         if (!cpu)
 143                 goto errmem;
 144
 145         memset(&act, 0, sizeof(act));
 146         sigfillset(&act.sa_mask);
 147         act.sa_sigaction = toggle_done;
 148         sigaction(SIGINT, &act, NULL);
 149
 150         if (params.mlockall) {
 151                 if (mlockall(MCL_CURRENT | MCL_FUTURE))
 152                         err(EXIT_FAILURE, "mlockall");
 153         }
 154
 155         if (!params.nthreads) /* default to the number of CPUs */
 156                 params.nthreads = perf_cpu_map__nr(cpu);
 157
 158         worker = calloc(params.nthreads, sizeof(*worker));
 159         if (!worker)
 160                 goto errmem;
 161
 162         if (!params.fshared)
 163                 futex_flag = FUTEX_PRIVATE_FLAG;
 164
 165         printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n",
 166                getpid(), params.nthreads, params.nfutexes, params.fshared ? "shared":"private", params.runtime);
 167
 168         init_stats(&throughput_stats);
 169         mutex_init(&thread_lock);
 170         cond_init(&thread_parent);
 171         cond_init(&thread_worker);
 172
 173         threads_starting = params.nthreads;
 174         pthread_attr_init(&thread_attr);
 175         gettimeofday(&bench__start, NULL);
 176
 177         nrcpus = perf_cpu_map__nr(cpu);
 178         cpuset = CPU_ALLOC(nrcpus);
 179         BUG_ON(!cpuset);
 180         size = CPU_ALLOC_SIZE(nrcpus);
 181
 182         for (i = 0; i < params.nthreads; i++) {
 183                 worker[i].tid = i;
 184                 worker[i].futex = calloc(params.nfutexes, sizeof(*worker[i].futex));
 185                 if (!worker[i].futex)
 186                         goto errmem;
 187
 188                 CPU_ZERO_S(size, cpuset);
 189
 190                 CPU_SET_S(perf_cpu_map__cpu(cpu, i % perf_cpu_map__nr(cpu)).cpu, size, cpuset);
 191                 ret = pthread_attr_setaffinity_np(&thread_attr, size, cpuset);
 192                 if (ret) {
 193                         CPU_FREE(cpuset);
 194                         err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
 195                 }
 196                 ret = pthread_create(&worker[i].thread, &thread_attr, workerfn,
 197                                      (void *)(struct worker *) &worker[i]);
 198                 if (ret) {
 199                         CPU_FREE(cpuset);
 200                         err(EXIT_FAILURE, "pthread_create");
 201                 }
 202
 203         }
 204         CPU_FREE(cpuset);
 205         pthread_attr_destroy(&thread_attr);
 206
 207         mutex_lock(&thread_lock);
 208         while (threads_starting)
 209                 cond_wait(&thread_parent, &thread_lock);
 210         cond_broadcast(&thread_worker);
 211         mutex_unlock(&thread_lock);
 212
 213         sleep(params.runtime);
 214         toggle_done(0, NULL, NULL);
 215
 216         for (i = 0; i < params.nthreads; i++) {
 217                 ret = pthread_join(worker[i].thread, NULL);
 218                 if (ret)
 219                         err(EXIT_FAILURE, "pthread_join");
 220         }
 221
 222         /* cleanup & report results */
 223         cond_destroy(&thread_parent);
 224         cond_destroy(&thread_worker);
 225         mutex_destroy(&thread_lock);
 226
 227         for (i = 0; i < params.nthreads; i++) {
 228                 unsigned long t = bench__runtime.tv_sec > 0 ?
 229                         worker[i].ops / bench__runtime.tv_sec : 0;
 230                 update_stats(&throughput_stats, t);
 231                 if (!params.silent) {
 232                         if (params.nfutexes == 1)
 233                                 printf("[thread %2d] futex: %p [ %ld ops/sec ]\n",
 234                                        worker[i].tid, &worker[i].futex[0], t);
 235                         else
 236                                 printf("[thread %2d] futexes: %p ... %p [ %ld ops/sec ]\n",
 237                                        worker[i].tid, &worker[i].futex[0],
 238                                        &worker[i].futex[params.nfutexes-1], t);
 239                 }
 240
 241                 zfree(&worker[i].futex);
 242         }
 243
 244         print_summary();
 245
 246         free(worker);
 247         free(cpu);
 248         return ret;
 249 errmem:
 250         err(EXIT_FAILURE, "calloc");
 251 }