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