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