tools/perf/bench/epoll-ctl.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2018 Davidlohr Bueso.
   4  *
   5  * Benchmark the various operations allowed for epoll_ctl(2).
   6  * The idea is to concurrently stress a single epoll instance
   7  */
   8 #ifdef HAVE_EVENTFD
   9 /* For the CLR_() macros */
  10 #include <string.h>
  11 #include <pthread.h>
  12
  13 #include <errno.h>
  14 #include <inttypes.h>
  15 #include <signal.h>
  16 #include <stdlib.h>
  17 #include <unistd.h>
  18 #include <linux/compiler.h>
  19 #include <linux/kernel.h>
  20 #include <sys/time.h>
  21 #include <sys/resource.h>
  22 #include <sys/epoll.h>
  23 #include <sys/eventfd.h>
  24 #include <internal/cpumap.h>
  25 #include <perf/cpumap.h>
  26
  27 #include "../util/stat.h"
  28 #include <subcmd/parse-options.h>
  29 #include "bench.h"
  30
  31 #include <err.h>
  32
  33 #define printinfo(fmt, arg...) \
  34         do { if (__verbose) printf(fmt, ## arg); } while (0)
  35
  36 static unsigned int nthreads = 0;
  37 static unsigned int nsecs    = 8;
  38 struct timeval start, end, runtime;
  39 static bool done, __verbose, randomize;
  40
  41 /*
  42  * epoll related shared variables.
  43  */
  44
  45 /* Maximum number of nesting allowed inside epoll sets */
  46 #define EPOLL_MAXNESTS 4
  47
  48 enum {
  49         OP_EPOLL_ADD,
  50         OP_EPOLL_MOD,
  51         OP_EPOLL_DEL,
  52         EPOLL_NR_OPS,
  53 };
  54
  55 static int epollfd;
  56 static int *epollfdp;
  57 static bool noaffinity;
  58 static unsigned int nested = 0;
  59
  60 /* amount of fds to monitor, per thread */
  61 static unsigned int nfds = 64;
  62
  63 static pthread_mutex_t thread_lock;
  64 static unsigned int threads_starting;
  65 static struct stats all_stats[EPOLL_NR_OPS];
  66 static pthread_cond_t thread_parent, thread_worker;
  67
  68 struct worker {
  69         int tid;
  70         pthread_t thread;
  71         unsigned long ops[EPOLL_NR_OPS];
  72         int *fdmap;
  73 };
  74
  75 static const struct option options[] = {
  76         OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
  77         OPT_UINTEGER('r', "runtime", &nsecs,    "Specify runtime (in seconds)"),
  78         OPT_UINTEGER('f', "nfds", &nfds, "Specify amount of file descriptors to monitor for each thread"),
  79         OPT_BOOLEAN( 'n', "noaffinity",  &noaffinity,   "Disables CPU affinity"),
  80         OPT_UINTEGER( 'N', "nested",  &nested,   "Nesting level epoll hierarchy (default is 0, no nesting)"),
  81         OPT_BOOLEAN( 'R', "randomize", &randomize,   "Perform random operations on random fds"),
  82         OPT_BOOLEAN( 'v', "verbose",  &__verbose,   "Verbose mode"),
  83         OPT_END()
  84 };
  85
  86 static const char * const bench_epoll_ctl_usage[] = {
  87         "perf bench epoll ctl <options>",
  88         NULL
  89 };
  90
  91 static void toggle_done(int sig __maybe_unused,
  92                         siginfo_t *info __maybe_unused,
  93                         void *uc __maybe_unused)
  94 {
  95         /* inform all threads that we're done for the day */
  96         done = true;
  97         gettimeofday(&end, NULL);
  98         timersub(&end, &start, &runtime);
  99 }
 100
 101 static void nest_epollfd(void)
 102 {
 103         unsigned int i;
 104         struct epoll_event ev;
 105
 106         if (nested > EPOLL_MAXNESTS)
 107                 nested = EPOLL_MAXNESTS;
 108         printinfo("Nesting level(s): %d\n", nested);
 109
 110         epollfdp = calloc(nested, sizeof(int));
 111         if (!epollfd)
 112                 err(EXIT_FAILURE, "calloc");
 113
 114         for (i = 0; i < nested; i++) {
 115                 epollfdp[i] = epoll_create(1);
 116                 if (epollfd < 0)
 117                         err(EXIT_FAILURE, "epoll_create");
 118         }
 119
 120         ev.events = EPOLLHUP; /* anything */
 121         ev.data.u64 = i; /* any number */
 122
 123         for (i = nested - 1; i; i--) {
 124                 if (epoll_ctl(epollfdp[i - 1], EPOLL_CTL_ADD,
 125                               epollfdp[i], &ev) < 0)
 126                         err(EXIT_FAILURE, "epoll_ctl");
 127         }
 128
 129         if (epoll_ctl(epollfd, EPOLL_CTL_ADD, *epollfdp, &ev) < 0)
 130                 err(EXIT_FAILURE, "epoll_ctl");
 131 }
 132
 133 static inline void do_epoll_op(struct worker *w, int op, int fd)
 134 {
 135         int error;
 136         struct epoll_event ev;
 137
 138         ev.events = EPOLLIN;
 139         ev.data.u64 = fd;
 140
 141         switch (op) {
 142         case OP_EPOLL_ADD:
 143                 error = epoll_ctl(epollfd, EPOLL_CTL_ADD, fd, &ev);
 144                 break;
 145         case OP_EPOLL_MOD:
 146                 ev.events = EPOLLOUT;
 147                 error = epoll_ctl(epollfd, EPOLL_CTL_MOD, fd, &ev);
 148                 break;
 149         case OP_EPOLL_DEL:
 150                 error = epoll_ctl(epollfd, EPOLL_CTL_DEL, fd, NULL);
 151                 break;
 152         default:
 153                 error = 1;
 154                 break;
 155         }
 156
 157         if (!error)
 158                 w->ops[op]++;
 159 }
 160
 161 static inline void do_random_epoll_op(struct worker *w)
 162 {
 163         unsigned long rnd1 = random(), rnd2 = random();
 164         int op, fd;
 165
 166         fd = w->fdmap[rnd1 % nfds];
 167         op = rnd2 % EPOLL_NR_OPS;
 168
 169         do_epoll_op(w, op, fd);
 170 }
 171
 172 static void *workerfn(void *arg)
 173 {
 174         unsigned int i;
 175         struct worker *w = (struct worker *) arg;
 176         struct timespec ts = { .tv_sec = 0,
 177                                .tv_nsec = 250 };
 178
 179         pthread_mutex_lock(&thread_lock);
 180         threads_starting--;
 181         if (!threads_starting)
 182                 pthread_cond_signal(&thread_parent);
 183         pthread_cond_wait(&thread_worker, &thread_lock);
 184         pthread_mutex_unlock(&thread_lock);
 185
 186         /* Let 'em loose */
 187         do {
 188                 /* random */
 189                 if (randomize) {
 190                         do_random_epoll_op(w);
 191                 } else {
 192                         for (i = 0; i < nfds; i++) {
 193                                 do_epoll_op(w, OP_EPOLL_ADD, w->fdmap[i]);
 194                                 do_epoll_op(w, OP_EPOLL_MOD, w->fdmap[i]);
 195                                 do_epoll_op(w, OP_EPOLL_DEL, w->fdmap[i]);
 196                         }
 197                 }
 198
 199                 nanosleep(&ts, NULL);
 200         }  while (!done);
 201
 202         return NULL;
 203 }
 204
 205 static void init_fdmaps(struct worker *w, int pct)
 206 {
 207         unsigned int i;
 208         int inc;
 209         struct epoll_event ev;
 210
 211         if (!pct)
 212                 return;
 213
 214         inc = 100/pct;
 215         for (i = 0; i < nfds; i+=inc) {
 216                 ev.data.fd = w->fdmap[i];
 217                 ev.events = EPOLLIN;
 218
 219                 if (epoll_ctl(epollfd, EPOLL_CTL_ADD, w->fdmap[i], &ev) < 0)
 220                         err(EXIT_FAILURE, "epoll_ct");
 221         }
 222 }
 223
 224 static int do_threads(struct worker *worker, struct perf_cpu_map *cpu)
 225 {
 226         pthread_attr_t thread_attr, *attrp = NULL;
 227         cpu_set_t cpuset;
 228         unsigned int i, j;
 229         int ret = 0;
 230
 231         if (!noaffinity)
 232                 pthread_attr_init(&thread_attr);
 233
 234         for (i = 0; i < nthreads; i++) {
 235                 struct worker *w = &worker[i];
 236
 237                 w->tid = i;
 238                 w->fdmap = calloc(nfds, sizeof(int));
 239                 if (!w->fdmap)
 240                         return 1;
 241
 242                 for (j = 0; j < nfds; j++) {
 243                         w->fdmap[j] = eventfd(0, EFD_NONBLOCK);
 244                         if (w->fdmap[j] < 0)
 245                                 err(EXIT_FAILURE, "eventfd");
 246                 }
 247
 248                 /*
 249                  * Lets add 50% of the fdmap to the epoll instance, and
 250                  * do it before any threads are started; otherwise there is
 251                  * an initial bias of the call failing  (mod and del ops).
 252                  */
 253                 if (randomize)
 254                         init_fdmaps(w, 50);
 255
 256                 if (!noaffinity) {
 257                         CPU_ZERO(&cpuset);
 258                         CPU_SET(cpu->map[i % cpu->nr], &cpuset);
 259
 260                         ret = pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset);
 261                         if (ret)
 262                                 err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
 263
 264                         attrp = &thread_attr;
 265                 }
 266
 267                 ret = pthread_create(&w->thread, attrp, workerfn,
 268                                      (void *)(struct worker *) w);
 269                 if (ret)
 270                         err(EXIT_FAILURE, "pthread_create");
 271         }
 272
 273         if (!noaffinity)
 274                 pthread_attr_destroy(&thread_attr);
 275
 276         return ret;
 277 }
 278
 279 static void print_summary(void)
 280 {
 281         int i;
 282         unsigned long avg[EPOLL_NR_OPS];
 283         double stddev[EPOLL_NR_OPS];
 284
 285         for (i = 0; i < EPOLL_NR_OPS; i++) {
 286                 avg[i] = avg_stats(&all_stats[i]);
 287                 stddev[i] = stddev_stats(&all_stats[i]);
 288         }
 289
 290         printf("\nAveraged %ld ADD operations (+- %.2f%%)\n",
 291                avg[OP_EPOLL_ADD], rel_stddev_stats(stddev[OP_EPOLL_ADD],
 292                                                    avg[OP_EPOLL_ADD]));
 293         printf("Averaged %ld MOD operations (+- %.2f%%)\n",
 294                avg[OP_EPOLL_MOD], rel_stddev_stats(stddev[OP_EPOLL_MOD],
 295                                                    avg[OP_EPOLL_MOD]));
 296         printf("Averaged %ld DEL operations (+- %.2f%%)\n",
 297                avg[OP_EPOLL_DEL], rel_stddev_stats(stddev[OP_EPOLL_DEL],
 298                                                    avg[OP_EPOLL_DEL]));
 299 }
 300
 301 int bench_epoll_ctl(int argc, const char **argv)
 302 {
 303         int j, ret = 0;
 304         struct sigaction act;
 305         struct worker *worker = NULL;
 306         struct perf_cpu_map *cpu;
 307         struct rlimit rl, prevrl;
 308         unsigned int i;
 309
 310         argc = parse_options(argc, argv, options, bench_epoll_ctl_usage, 0);
 311         if (argc) {
 312                 usage_with_options(bench_epoll_ctl_usage, options);
 313                 exit(EXIT_FAILURE);
 314         }
 315
 316         sigfillset(&act.sa_mask);
 317         act.sa_sigaction = toggle_done;
 318         sigaction(SIGINT, &act, NULL);
 319
 320         cpu = perf_cpu_map__new(NULL);
 321         if (!cpu)
 322                 goto errmem;
 323
 324         /* a single, main epoll instance */
 325         epollfd = epoll_create(1);
 326         if (epollfd < 0)
 327                 err(EXIT_FAILURE, "epoll_create");
 328
 329         /*
 330          * Deal with nested epolls, if any.
 331          */
 332         if (nested)
 333                 nest_epollfd();
 334
 335         /* default to the number of CPUs */
 336         if (!nthreads)
 337                 nthreads = cpu->nr;
 338
 339         worker = calloc(nthreads, sizeof(*worker));
 340         if (!worker)
 341                 goto errmem;
 342
 343         if (getrlimit(RLIMIT_NOFILE, &prevrl))
 344             err(EXIT_FAILURE, "getrlimit");
 345         rl.rlim_cur = rl.rlim_max = nfds * nthreads * 2 + 50;
 346         printinfo("Setting RLIMIT_NOFILE rlimit from %" PRIu64 " to: %" PRIu64 "\n",
 347                   (uint64_t)prevrl.rlim_max, (uint64_t)rl.rlim_max);
 348         if (setrlimit(RLIMIT_NOFILE, &rl) < 0)
 349                 err(EXIT_FAILURE, "setrlimit");
 350
 351         printf("Run summary [PID %d]: %d threads doing epoll_ctl ops "
 352                "%d file-descriptors for %d secs.\n\n",
 353                getpid(), nthreads, nfds, nsecs);
 354
 355         for (i = 0; i < EPOLL_NR_OPS; i++)
 356                 init_stats(&all_stats[i]);
 357
 358         pthread_mutex_init(&thread_lock, NULL);
 359         pthread_cond_init(&thread_parent, NULL);
 360         pthread_cond_init(&thread_worker, NULL);
 361
 362         threads_starting = nthreads;
 363
 364         gettimeofday(&start, NULL);
 365
 366         do_threads(worker, cpu);
 367
 368         pthread_mutex_lock(&thread_lock);
 369         while (threads_starting)
 370                 pthread_cond_wait(&thread_parent, &thread_lock);
 371         pthread_cond_broadcast(&thread_worker);
 372         pthread_mutex_unlock(&thread_lock);
 373
 374         sleep(nsecs);
 375         toggle_done(0, NULL, NULL);
 376         printinfo("main thread: toggling done\n");
 377
 378         for (i = 0; i < nthreads; i++) {
 379                 ret = pthread_join(worker[i].thread, NULL);
 380                 if (ret)
 381                         err(EXIT_FAILURE, "pthread_join");
 382         }
 383
 384         /* cleanup & report results */
 385         pthread_cond_destroy(&thread_parent);
 386         pthread_cond_destroy(&thread_worker);
 387         pthread_mutex_destroy(&thread_lock);
 388
 389         for (i = 0; i < nthreads; i++) {
 390                 unsigned long t[EPOLL_NR_OPS];
 391
 392                 for (j = 0; j < EPOLL_NR_OPS; j++) {
 393                         t[j] = worker[i].ops[j];
 394                         update_stats(&all_stats[j], t[j]);
 395                 }
 396
 397                 if (nfds == 1)
 398                         printf("[thread %2d] fdmap: %p [ add: %04ld; mod: %04ld; del: %04lds ops ]\n",
 399                                worker[i].tid, &worker[i].fdmap[0],
 400                                t[OP_EPOLL_ADD], t[OP_EPOLL_MOD], t[OP_EPOLL_DEL]);
 401                 else
 402                         printf("[thread %2d] fdmap: %p ... %p [ add: %04ld ops; mod: %04ld ops; del: %04ld ops ]\n",
 403                                worker[i].tid, &worker[i].fdmap[0],
 404                                &worker[i].fdmap[nfds-1],
 405                                t[OP_EPOLL_ADD], t[OP_EPOLL_MOD], t[OP_EPOLL_DEL]);
 406         }
 407
 408         print_summary();
 409
 410         close(epollfd);
 411         return ret;
 412 errmem:
 413         err(EXIT_FAILURE, "calloc");
 414 }
 415 #endif // HAVE_EVENTFD