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 <sys/time.h> 22 23 #include "../util/stat.h" 24 #include <subcmd/parse-options.h> 25 #include "bench.h" 26 #include "futex.h" 27 #include "cpumap.h" 28 29 #include <err.h> 30 31 static unsigned int nthreads = 0; 32 static unsigned int nsecs = 10; 33 /* amount of futexes per thread */ 34 static unsigned int nfutexes = 1024; 35 static bool fshared = false, done = false, silent = false; 36 static int futex_flag = 0; 37 38 struct timeval start, end, runtime; 39 static pthread_mutex_t thread_lock; 40 static unsigned int threads_starting; 41 static struct stats throughput_stats; 42 static pthread_cond_t thread_parent, thread_worker; 43 44 struct worker { 45 int tid; 46 u_int32_t *futex; 47 pthread_t thread; 48 unsigned long ops; 49 }; 50 51 static const struct option options[] = { 52 OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"), 53 OPT_UINTEGER('r', "runtime", &nsecs, "Specify runtime (in seconds)"), 54 OPT_UINTEGER('f', "futexes", &nfutexes, "Specify amount of futexes per threads"), 55 OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"), 56 OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"), 57 OPT_END() 58 }; 59 60 static const char * const bench_futex_hash_usage[] = { 61 "perf bench futex hash <options>", 62 NULL 63 }; 64 65 static void *workerfn(void *arg) 66 { 67 int ret; 68 struct worker *w = (struct worker *) arg; 69 unsigned int i; 70 unsigned long ops = w->ops; /* avoid cacheline bouncing */ 71 72 pthread_mutex_lock(&thread_lock); 73 threads_starting--; 74 if (!threads_starting) 75 pthread_cond_signal(&thread_parent); 76 pthread_cond_wait(&thread_worker, &thread_lock); 77 pthread_mutex_unlock(&thread_lock); 78 79 do { 80 for (i = 0; i < nfutexes; i++, ops++) { 81 /* 82 * We want the futex calls to fail in order to stress 83 * the hashing of uaddr and not measure other steps, 84 * such as internal waitqueue handling, thus enlarging 85 * the critical region protected by hb->lock. 86 */ 87 ret = futex_wait(&w->futex[i], 1234, NULL, futex_flag); 88 if (!silent && 89 (!ret || errno != EAGAIN || errno != EWOULDBLOCK)) 90 warn("Non-expected futex return call"); 91 } 92 } while (!done); 93 94 w->ops = ops; 95 return NULL; 96 } 97 98 static void toggle_done(int sig __maybe_unused, 99 siginfo_t *info __maybe_unused, 100 void *uc __maybe_unused) 101 { 102 /* inform all threads that we're done for the day */ 103 done = true; 104 gettimeofday(&end, NULL); 105 timersub(&end, &start, &runtime); 106 } 107 108 static void print_summary(void) 109 { 110 unsigned long avg = avg_stats(&throughput_stats); 111 double stddev = stddev_stats(&throughput_stats); 112 113 printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n", 114 !silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg), 115 (int) runtime.tv_sec); 116 } 117 118 int bench_futex_hash(int argc, const char **argv) 119 { 120 int ret = 0; 121 cpu_set_t cpuset; 122 struct sigaction act; 123 unsigned int i; 124 pthread_attr_t thread_attr; 125 struct worker *worker = NULL; 126 struct cpu_map *cpu; 127 128 argc = parse_options(argc, argv, options, bench_futex_hash_usage, 0); 129 if (argc) { 130 usage_with_options(bench_futex_hash_usage, options); 131 exit(EXIT_FAILURE); 132 } 133 134 cpu = cpu_map__new(NULL); 135 if (!cpu) 136 goto errmem; 137 138 sigfillset(&act.sa_mask); 139 act.sa_sigaction = toggle_done; 140 sigaction(SIGINT, &act, NULL); 141 142 if (!nthreads) /* default to the number of CPUs */ 143 nthreads = cpu->nr; 144 145 worker = calloc(nthreads, sizeof(*worker)); 146 if (!worker) 147 goto errmem; 148 149 if (!fshared) 150 futex_flag = FUTEX_PRIVATE_FLAG; 151 152 printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n", 153 getpid(), nthreads, nfutexes, fshared ? "shared":"private", nsecs); 154 155 init_stats(&throughput_stats); 156 pthread_mutex_init(&thread_lock, NULL); 157 pthread_cond_init(&thread_parent, NULL); 158 pthread_cond_init(&thread_worker, NULL); 159 160 threads_starting = nthreads; 161 pthread_attr_init(&thread_attr); 162 gettimeofday(&start, NULL); 163 for (i = 0; i < nthreads; i++) { 164 worker[i].tid = i; 165 worker[i].futex = calloc(nfutexes, sizeof(*worker[i].futex)); 166 if (!worker[i].futex) 167 goto errmem; 168 169 CPU_ZERO(&cpuset); 170 CPU_SET(cpu->map[i % cpu->nr], &cpuset); 171 172 ret = pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset); 173 if (ret) 174 err(EXIT_FAILURE, "pthread_attr_setaffinity_np"); 175 176 ret = pthread_create(&worker[i].thread, &thread_attr, workerfn, 177 (void *)(struct worker *) &worker[i]); 178 if (ret) 179 err(EXIT_FAILURE, "pthread_create"); 180 181 } 182 pthread_attr_destroy(&thread_attr); 183 184 pthread_mutex_lock(&thread_lock); 185 while (threads_starting) 186 pthread_cond_wait(&thread_parent, &thread_lock); 187 pthread_cond_broadcast(&thread_worker); 188 pthread_mutex_unlock(&thread_lock); 189 190 sleep(nsecs); 191 toggle_done(0, NULL, NULL); 192 193 for (i = 0; i < nthreads; i++) { 194 ret = pthread_join(worker[i].thread, NULL); 195 if (ret) 196 err(EXIT_FAILURE, "pthread_join"); 197 } 198 199 /* cleanup & report results */ 200 pthread_cond_destroy(&thread_parent); 201 pthread_cond_destroy(&thread_worker); 202 pthread_mutex_destroy(&thread_lock); 203 204 for (i = 0; i < nthreads; i++) { 205 unsigned long t = worker[i].ops/runtime.tv_sec; 206 update_stats(&throughput_stats, t); 207 if (!silent) { 208 if (nfutexes == 1) 209 printf("[thread %2d] futex: %p [ %ld ops/sec ]\n", 210 worker[i].tid, &worker[i].futex[0], t); 211 else 212 printf("[thread %2d] futexes: %p ... %p [ %ld ops/sec ]\n", 213 worker[i].tid, &worker[i].futex[0], 214 &worker[i].futex[nfutexes-1], t); 215 } 216 217 free(worker[i].futex); 218 } 219 220 print_summary(); 221 222 free(worker); 223 free(cpu); 224 return ret; 225 errmem: 226 err(EXIT_FAILURE, "calloc"); 227 } 228