linux/tools/perf/bench/epoll-ctl.c
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   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
  36static unsigned int nthreads = 0;
  37static unsigned int nsecs    = 8;
  38struct timeval start, end, runtime;
  39static 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
  48enum {
  49        OP_EPOLL_ADD,
  50        OP_EPOLL_MOD,
  51        OP_EPOLL_DEL,
  52        EPOLL_NR_OPS,
  53};
  54
  55static int epollfd;
  56static int *epollfdp;
  57static bool noaffinity;
  58static unsigned int nested = 0;
  59
  60/* amount of fds to monitor, per thread */
  61static unsigned int nfds = 64;
  62
  63static pthread_mutex_t thread_lock;
  64static unsigned int threads_starting;
  65static struct stats all_stats[EPOLL_NR_OPS];
  66static pthread_cond_t thread_parent, thread_worker;
  67
  68struct worker {
  69        int tid;
  70        pthread_t thread;
  71        unsigned long ops[EPOLL_NR_OPS];
  72        int *fdmap;
  73};
  74
  75static 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
  86static const char * const bench_epoll_ctl_usage[] = {
  87        "perf bench epoll ctl <options>",
  88        NULL
  89};
  90
  91static 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
 101static 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
 133static 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
 161static 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
 172static 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
 205static 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
 224static 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
 279static 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
 301int 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;
 412errmem:
 413        err(EXIT_FAILURE, "calloc");
 414}
 415#endif // HAVE_EVENTFD
 416