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 <pthread.h> 13 14 #include <errno.h> 15 #include <signal.h> 16 #include <stdlib.h> 17 #include <linux/compiler.h> 18 #include <linux/kernel.h> 19 #include <sys/time.h> 20 21 #include "../util/stat.h" 22 #include <subcmd/parse-options.h> 23 #include "bench.h" 24 #include "futex.h" 25 26 #include <err.h> 27 #include <sys/time.h> 28 29 static unsigned int nthreads = 0; 30 static unsigned int nsecs = 10; 31 /* amount of futexes per thread */ 32 static unsigned int nfutexes = 1024; 33 static bool fshared = false, done = false, silent = false; 34 static int futex_flag = 0; 35 36 struct timeval start, end, 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 const struct option options[] = { 50 OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"), 51 OPT_UINTEGER('r', "runtime", &nsecs, "Specify runtime (in seconds)"), 52 OPT_UINTEGER('f', "futexes", &nfutexes, "Specify amount of futexes per threads"), 53 OPT_BOOLEAN( 's', "silent", &silent, "Silent mode: do not display data/details"), 54 OPT_BOOLEAN( 'S', "shared", &fshared, "Use shared futexes instead of private ones"), 55 OPT_END() 56 }; 57 58 static const char * const bench_futex_hash_usage[] = { 59 "perf bench futex hash <options>", 60 NULL 61 }; 62 63 static void *workerfn(void *arg) 64 { 65 int ret; 66 unsigned int i; 67 struct worker *w = (struct worker *) arg; 68 69 pthread_mutex_lock(&thread_lock); 70 threads_starting--; 71 if (!threads_starting) 72 pthread_cond_signal(&thread_parent); 73 pthread_cond_wait(&thread_worker, &thread_lock); 74 pthread_mutex_unlock(&thread_lock); 75 76 do { 77 for (i = 0; i < nfutexes; i++, w->ops++) { 78 /* 79 * We want the futex calls to fail in order to stress 80 * the hashing of uaddr and not measure other steps, 81 * such as internal waitqueue handling, thus enlarging 82 * the critical region protected by hb->lock. 83 */ 84 ret = futex_wait(&w->futex[i], 1234, NULL, futex_flag); 85 if (!silent && 86 (!ret || errno != EAGAIN || errno != EWOULDBLOCK)) 87 warn("Non-expected futex return call"); 88 } 89 } while (!done); 90 91 return NULL; 92 } 93 94 static void toggle_done(int sig __maybe_unused, 95 siginfo_t *info __maybe_unused, 96 void *uc __maybe_unused) 97 { 98 /* inform all threads that we're done for the day */ 99 done = true; 100 gettimeofday(&end, NULL); 101 timersub(&end, &start, &runtime); 102 } 103 104 static void print_summary(void) 105 { 106 unsigned long avg = avg_stats(&throughput_stats); 107 double stddev = stddev_stats(&throughput_stats); 108 109 printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n", 110 !silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg), 111 (int) runtime.tv_sec); 112 } 113 114 int bench_futex_hash(int argc, const char **argv, 115 const char *prefix __maybe_unused) 116 { 117 int ret = 0; 118 cpu_set_t cpu; 119 struct sigaction act; 120 unsigned int i, ncpus; 121 pthread_attr_t thread_attr; 122 struct worker *worker = NULL; 123 124 argc = parse_options(argc, argv, options, bench_futex_hash_usage, 0); 125 if (argc) { 126 usage_with_options(bench_futex_hash_usage, options); 127 exit(EXIT_FAILURE); 128 } 129 130 ncpus = sysconf(_SC_NPROCESSORS_ONLN); 131 132 sigfillset(&act.sa_mask); 133 act.sa_sigaction = toggle_done; 134 sigaction(SIGINT, &act, NULL); 135 136 if (!nthreads) /* default to the number of CPUs */ 137 nthreads = ncpus; 138 139 worker = calloc(nthreads, sizeof(*worker)); 140 if (!worker) 141 goto errmem; 142 143 if (!fshared) 144 futex_flag = FUTEX_PRIVATE_FLAG; 145 146 printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n", 147 getpid(), nthreads, nfutexes, fshared ? "shared":"private", nsecs); 148 149 init_stats(&throughput_stats); 150 pthread_mutex_init(&thread_lock, NULL); 151 pthread_cond_init(&thread_parent, NULL); 152 pthread_cond_init(&thread_worker, NULL); 153 154 threads_starting = nthreads; 155 pthread_attr_init(&thread_attr); 156 gettimeofday(&start, NULL); 157 for (i = 0; i < nthreads; i++) { 158 worker[i].tid = i; 159 worker[i].futex = calloc(nfutexes, sizeof(*worker[i].futex)); 160 if (!worker[i].futex) 161 goto errmem; 162 163 CPU_ZERO(&cpu); 164 CPU_SET(i % ncpus, &cpu); 165 166 ret = pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpu); 167 if (ret) 168 err(EXIT_FAILURE, "pthread_attr_setaffinity_np"); 169 170 ret = pthread_create(&worker[i].thread, &thread_attr, workerfn, 171 (void *)(struct worker *) &worker[i]); 172 if (ret) 173 err(EXIT_FAILURE, "pthread_create"); 174 175 } 176 pthread_attr_destroy(&thread_attr); 177 178 pthread_mutex_lock(&thread_lock); 179 while (threads_starting) 180 pthread_cond_wait(&thread_parent, &thread_lock); 181 pthread_cond_broadcast(&thread_worker); 182 pthread_mutex_unlock(&thread_lock); 183 184 sleep(nsecs); 185 toggle_done(0, NULL, NULL); 186 187 for (i = 0; i < nthreads; i++) { 188 ret = pthread_join(worker[i].thread, NULL); 189 if (ret) 190 err(EXIT_FAILURE, "pthread_join"); 191 } 192 193 /* cleanup & report results */ 194 pthread_cond_destroy(&thread_parent); 195 pthread_cond_destroy(&thread_worker); 196 pthread_mutex_destroy(&thread_lock); 197 198 for (i = 0; i < nthreads; i++) { 199 unsigned long t = worker[i].ops/runtime.tv_sec; 200 update_stats(&throughput_stats, t); 201 if (!silent) { 202 if (nfutexes == 1) 203 printf("[thread %2d] futex: %p [ %ld ops/sec ]\n", 204 worker[i].tid, &worker[i].futex[0], t); 205 else 206 printf("[thread %2d] futexes: %p ... %p [ %ld ops/sec ]\n", 207 worker[i].tid, &worker[i].futex[0], 208 &worker[i].futex[nfutexes-1], t); 209 } 210 211 free(worker[i].futex); 212 } 213 214 print_summary(); 215 216 free(worker); 217 return ret; 218 errmem: 219 err(EXIT_FAILURE, "calloc"); 220 } 221