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/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", ¶ms.nthreads, "Specify amount of threads"), 56 OPT_UINTEGER('r', "runtime", ¶ms.runtime, "Specify runtime (in seconds)"), 57 OPT_UINTEGER('f', "futexes", ¶ms.nfutexes, "Specify amount of futexes per threads"), 58 OPT_BOOLEAN( 's', "silent", ¶ms.silent, "Silent mode: do not display data/details"), 59 OPT_BOOLEAN( 'S', "shared", ¶ms.fshared, "Use shared futexes instead of private ones"), 60 OPT_BOOLEAN( 'm', "mlockall", ¶ms.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 } 251