tools/perf/bench/futex-hash.c

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