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 <internal/cpumap.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 unsigned int nthreads = 0; 34 static unsigned int nsecs = 10; 35 /* amount of futexes per thread */ 36 static unsigned int nfutexes = 1024; 37 static bool fshared = false, done = false, silent = false; 38 static int futex_flag = 0; 39 40 struct timeval bench__start, bench__end, bench__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 struct worker { 47 int tid; 48 u_int32_t *futex; 49 pthread_t thread; 50 unsigned long ops; 51 }; 52 53 static const struct option options[] = { 54 OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"), 55 OPT_UINTEGER('r', "runtime", &nsecs, "Specify runtime (in seconds)"), 56 OPT_UINTEGER('f', "futexes", &nfutexes, "Specify amount of futexes per threads"), 57 OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"), 58 OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"), 59 OPT_END() 60 }; 61 62 static const char * const bench_futex_hash_usage[] = { 63 "perf bench futex hash <options>", 64 NULL 65 }; 66 67 static void *workerfn(void *arg) 68 { 69 int ret; 70 struct worker *w = (struct worker *) arg; 71 unsigned int i; 72 unsigned long ops = w->ops; /* avoid cacheline bouncing */ 73 74 pthread_mutex_lock(&thread_lock); 75 threads_starting--; 76 if (!threads_starting) 77 pthread_cond_signal(&thread_parent); 78 pthread_cond_wait(&thread_worker, &thread_lock); 79 pthread_mutex_unlock(&thread_lock); 80 81 do { 82 for (i = 0; i < nfutexes; i++, ops++) { 83 /* 84 * We want the futex calls to fail in order to stress 85 * the hashing of uaddr and not measure other steps, 86 * such as internal waitqueue handling, thus enlarging 87 * the critical region protected by hb->lock. 88 */ 89 ret = futex_wait(&w->futex[i], 1234, NULL, futex_flag); 90 if (!silent && 91 (!ret || errno != EAGAIN || errno != EWOULDBLOCK)) 92 warn("Non-expected futex return call"); 93 } 94 } while (!done); 95 96 w->ops = ops; 97 return NULL; 98 } 99 100 static void toggle_done(int sig __maybe_unused, 101 siginfo_t *info __maybe_unused, 102 void *uc __maybe_unused) 103 { 104 /* inform all threads that we're done for the day */ 105 done = true; 106 gettimeofday(&bench__end, NULL); 107 timersub(&bench__end, &bench__start, &bench__runtime); 108 } 109 110 static void print_summary(void) 111 { 112 unsigned long avg = avg_stats(&throughput_stats); 113 double stddev = stddev_stats(&throughput_stats); 114 115 printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n", 116 !silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg), 117 (int)bench__runtime.tv_sec); 118 } 119 120 int bench_futex_hash(int argc, const char **argv) 121 { 122 int ret = 0; 123 cpu_set_t cpuset; 124 struct sigaction act; 125 unsigned int i; 126 pthread_attr_t thread_attr; 127 struct worker *worker = NULL; 128 struct perf_cpu_map *cpu; 129 130 argc = parse_options(argc, argv, options, bench_futex_hash_usage, 0); 131 if (argc) { 132 usage_with_options(bench_futex_hash_usage, options); 133 exit(EXIT_FAILURE); 134 } 135 136 cpu = perf_cpu_map__new(NULL); 137 if (!cpu) 138 goto errmem; 139 140 memset(&act, 0, sizeof(act)); 141 sigfillset(&act.sa_mask); 142 act.sa_sigaction = toggle_done; 143 sigaction(SIGINT, &act, NULL); 144 145 if (!nthreads) /* default to the number of CPUs */ 146 nthreads = cpu->nr; 147 148 worker = calloc(nthreads, sizeof(*worker)); 149 if (!worker) 150 goto errmem; 151 152 if (!fshared) 153 futex_flag = FUTEX_PRIVATE_FLAG; 154 155 printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n", 156 getpid(), nthreads, nfutexes, fshared ? "shared":"private", nsecs); 157 158 init_stats(&throughput_stats); 159 pthread_mutex_init(&thread_lock, NULL); 160 pthread_cond_init(&thread_parent, NULL); 161 pthread_cond_init(&thread_worker, NULL); 162 163 threads_starting = nthreads; 164 pthread_attr_init(&thread_attr); 165 gettimeofday(&bench__start, NULL); 166 for (i = 0; i < nthreads; i++) { 167 worker[i].tid = i; 168 worker[i].futex = calloc(nfutexes, sizeof(*worker[i].futex)); 169 if (!worker[i].futex) 170 goto errmem; 171 172 CPU_ZERO(&cpuset); 173 CPU_SET(cpu->map[i % cpu->nr], &cpuset); 174 175 ret = pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset); 176 if (ret) 177 err(EXIT_FAILURE, "pthread_attr_setaffinity_np"); 178 179 ret = pthread_create(&worker[i].thread, &thread_attr, workerfn, 180 (void *)(struct worker *) &worker[i]); 181 if (ret) 182 err(EXIT_FAILURE, "pthread_create"); 183 184 } 185 pthread_attr_destroy(&thread_attr); 186 187 pthread_mutex_lock(&thread_lock); 188 while (threads_starting) 189 pthread_cond_wait(&thread_parent, &thread_lock); 190 pthread_cond_broadcast(&thread_worker); 191 pthread_mutex_unlock(&thread_lock); 192 193 sleep(nsecs); 194 toggle_done(0, NULL, NULL); 195 196 for (i = 0; i < nthreads; i++) { 197 ret = pthread_join(worker[i].thread, NULL); 198 if (ret) 199 err(EXIT_FAILURE, "pthread_join"); 200 } 201 202 /* cleanup & report results */ 203 pthread_cond_destroy(&thread_parent); 204 pthread_cond_destroy(&thread_worker); 205 pthread_mutex_destroy(&thread_lock); 206 207 for (i = 0; i < nthreads; i++) { 208 unsigned long t = bench__runtime.tv_sec > 0 ? 209 worker[i].ops / bench__runtime.tv_sec : 0; 210 update_stats(&throughput_stats, t); 211 if (!silent) { 212 if (nfutexes == 1) 213 printf("[thread %2d] futex: %p [ %ld ops/sec ]\n", 214 worker[i].tid, &worker[i].futex[0], t); 215 else 216 printf("[thread %2d] futexes: %p ... %p [ %ld ops/sec ]\n", 217 worker[i].tid, &worker[i].futex[0], 218 &worker[i].futex[nfutexes-1], t); 219 } 220 221 zfree(&worker[i].futex); 222 } 223 224 print_summary(); 225 226 free(worker); 227 free(cpu); 228 return ret; 229 errmem: 230 err(EXIT_FAILURE, "calloc"); 231 } 232