--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+#ifdef HAVE_EVENTFD
+/*
+ * Copyright (C) 2018 Davidlohr Bueso.
+ *
+ * This program benchmarks concurrent epoll_wait(2) monitoring multiple
+ * file descriptors under one or two load balancing models. The first,
+ * and default, is the single/combined queueing (which refers to a single
+ * epoll instance for N worker threads):
+ *
+ * |---> [worker A]
+ * |---> [worker B]
+ * [combined queue] .---> [worker C]
+ * |---> [worker D]
+ * |---> [worker E]
+ *
+ * While the second model, enabled via --multiq option, uses multiple
+ * queueing (which refers to one epoll instance per worker). For example,
+ * short lived tcp connections in a high throughput httpd server will
+ * ditribute the accept()'ing connections across CPUs. In this case each
+ * worker does a limited amount of processing.
+ *
+ * [queue A] ---> [worker]
+ * [queue B] ---> [worker]
+ * [queue C] ---> [worker]
+ * [queue D] ---> [worker]
+ * [queue E] ---> [worker]
+ *
+ * Naturally, the single queue will enforce more concurrency on the epoll
+ * instance, and can therefore scale poorly compared to multiple queues.
+ * However, this is a benchmark raw data and must be taken with a grain of
+ * salt when choosing how to make use of sys_epoll.
+
+ * Each thread has a number of private, nonblocking file descriptors,
+ * referred to as fdmap. A writer thread will constantly be writing to
+ * the fdmaps of all threads, minimizing each threads's chances of
+ * epoll_wait not finding any ready read events and blocking as this
+ * is not what we want to stress. The size of the fdmap can be adjusted
+ * by the user; enlarging the value will increase the chances of
+ * epoll_wait(2) blocking as the lineal writer thread will take "longer",
+ * at least at a high level.
+ *
+ * Note that because fds are private to each thread, this workload does
+ * not stress scenarios where multiple tasks are awoken per ready IO; ie:
+ * EPOLLEXCLUSIVE semantics.
+ *
+ * The end result/metric is throughput: number of ops/second where an
+ * operation consists of:
+ *
+ * epoll_wait(2) + [others]
+ *
+ * ... where [others] is the cost of re-adding the fd (EPOLLET),
+ * or rearming it (EPOLLONESHOT).
+ *
+ *
+ * The purpose of this is program is that it be useful for measuring
+ * kernel related changes to the sys_epoll, and not comparing different
+ * IO polling methods, for example. Hence everything is very adhoc and
+ * outputs raw microbenchmark numbers. Also this uses eventfd, similar
+ * tools tend to use pipes or sockets, but the result is the same.
+ */
+
+/* For the CLR_() macros */
+#include <string.h>
+#include <pthread.h>
+
+#include <errno.h>
+#include <inttypes.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <linux/compiler.h>
+#include <linux/kernel.h>
+#include <sys/time.h>
+#include <sys/resource.h>
+#include <sys/epoll.h>
+#include <sys/eventfd.h>
+#include <sys/types.h>
+
+#include "../util/stat.h"
+#include <subcmd/parse-options.h>
+#include "bench.h"
+#include "cpumap.h"
+
+#include <err.h>
+
+#define printinfo(fmt, arg...) \
+ do { if (__verbose) { printf(fmt, ## arg); fflush(stdout); } } while (0)
+
+static unsigned int nthreads = 0;
+static unsigned int nsecs = 8;
+struct timeval start, end, runtime;
+static bool wdone, done, __verbose, randomize, nonblocking;
+
+/*
+ * epoll related shared variables.
+ */
+
+/* Maximum number of nesting allowed inside epoll sets */
+#define EPOLL_MAXNESTS 4
+
+static int epollfd;
+static int *epollfdp;
+static bool noaffinity;
+static unsigned int nested = 0;
+static bool et; /* edge-trigger */
+static bool oneshot;
+static bool multiq; /* use an epoll instance per thread */
+
+/* amount of fds to monitor, per thread */
+static unsigned int nfds = 64;
+
+static pthread_mutex_t thread_lock;
+static unsigned int threads_starting;
+static struct stats throughput_stats;
+static pthread_cond_t thread_parent, thread_worker;
+
+struct worker {
+ int tid;
+ int epollfd; /* for --multiq */
+ pthread_t thread;
+ unsigned long ops;
+ int *fdmap;
+};
+
+static const struct option options[] = {
+ /* general benchmark options */
+ OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
+ OPT_UINTEGER('r', "runtime", &nsecs, "Specify runtime (in seconds)"),
+ OPT_UINTEGER('f', "nfds", &nfds, "Specify amount of file descriptors to monitor for each thread"),
+ OPT_BOOLEAN( 'n', "noaffinity", &noaffinity, "Disables CPU affinity"),
+ OPT_BOOLEAN('R', "randomize", &randomize, "Enable random write behaviour (default is lineal)"),
+ OPT_BOOLEAN( 'v', "verbose", &__verbose, "Verbose mode"),
+
+ /* epoll specific options */
+ OPT_BOOLEAN( 'm', "multiq", &multiq, "Use multiple epoll instances (one per thread)"),
+ OPT_BOOLEAN( 'B', "nonblocking", &nonblocking, "Nonblocking epoll_wait(2) behaviour"),
+ OPT_UINTEGER( 'N', "nested", &nested, "Nesting level epoll hierarchy (default is 0, no nesting)"),
+ OPT_BOOLEAN( 'S', "oneshot", &oneshot, "Use EPOLLONESHOT semantics"),
+ OPT_BOOLEAN( 'E', "edge", &et, "Use Edge-triggered interface (default is LT)"),
+
+ OPT_END()
+};
+
+static const char * const bench_epoll_wait_usage[] = {
+ "perf bench epoll wait <options>",
+ NULL
+};
+
+
+/*
+ * Arrange the N elements of ARRAY in random order.
+ * Only effective if N is much smaller than RAND_MAX;
+ * if this may not be the case, use a better random
+ * number generator. -- Ben Pfaff.
+ */
+static void shuffle(void *array, size_t n, size_t size)
+{
+ char *carray = array;
+ void *aux;
+ size_t i;
+
+ if (n <= 1)
+ return;
+
+ aux = calloc(1, size);
+ if (!aux)
+ err(EXIT_FAILURE, "calloc");
+
+ for (i = 1; i < n; ++i) {
+ size_t j = i + rand() / (RAND_MAX / (n - i) + 1);
+ j *= size;
+
+ memcpy(aux, &carray[j], size);
+ memcpy(&carray[j], &carray[i*size], size);
+ memcpy(&carray[i*size], aux, size);
+ }
+
+ free(aux);
+}
+
+
+static void *workerfn(void *arg)
+{
+ int fd, ret, r;
+ struct worker *w = (struct worker *) arg;
+ unsigned long ops = w->ops;
+ struct epoll_event ev;
+ uint64_t val;
+ int to = nonblocking? 0 : -1;
+ int efd = multiq ? w->epollfd : epollfd;
+
+ pthread_mutex_lock(&thread_lock);
+ threads_starting--;
+ if (!threads_starting)
+ pthread_cond_signal(&thread_parent);
+ pthread_cond_wait(&thread_worker, &thread_lock);
+ pthread_mutex_unlock(&thread_lock);
+
+ do {
+ /*
+ * Block undefinitely waiting for the IN event.
+ * In order to stress the epoll_wait(2) syscall,
+ * call it event per event, instead of a larger
+ * batch (max)limit.
+ */
+ do {
+ ret = epoll_wait(efd, &ev, 1, to);
+ } while (ret < 0 && errno == EINTR);
+ if (ret < 0)
+ err(EXIT_FAILURE, "epoll_wait");
+
+ fd = ev.data.fd;
+
+ do {
+ r = read(fd, &val, sizeof(val));
+ } while (!done && (r < 0 && errno == EAGAIN));
+
+ if (et) {
+ ev.events = EPOLLIN | EPOLLET;
+ ret = epoll_ctl(efd, EPOLL_CTL_ADD, fd, &ev);
+ }
+
+ if (oneshot) {
+ /* rearm the file descriptor with a new event mask */
+ ev.events |= EPOLLIN | EPOLLONESHOT;
+ ret = epoll_ctl(efd, EPOLL_CTL_MOD, fd, &ev);
+ }
+
+ ops++;
+ } while (!done);
+
+ if (multiq)
+ close(w->epollfd);
+
+ w->ops = ops;
+ return NULL;
+}
+
+static void nest_epollfd(struct worker *w)
+{
+ unsigned int i;
+ struct epoll_event ev;
+ int efd = multiq ? w->epollfd : epollfd;
+
+ if (nested > EPOLL_MAXNESTS)
+ nested = EPOLL_MAXNESTS;
+
+ epollfdp = calloc(nested, sizeof(*epollfdp));
+ if (!epollfdp)
+ err(EXIT_FAILURE, "calloc");
+
+ for (i = 0; i < nested; i++) {
+ epollfdp[i] = epoll_create(1);
+ if (epollfdp[i] < 0)
+ err(EXIT_FAILURE, "epoll_create");
+ }
+
+ ev.events = EPOLLHUP; /* anything */
+ ev.data.u64 = i; /* any number */
+
+ for (i = nested - 1; i; i--) {
+ if (epoll_ctl(epollfdp[i - 1], EPOLL_CTL_ADD,
+ epollfdp[i], &ev) < 0)
+ err(EXIT_FAILURE, "epoll_ctl");
+ }
+
+ if (epoll_ctl(efd, EPOLL_CTL_ADD, *epollfdp, &ev) < 0)
+ err(EXIT_FAILURE, "epoll_ctl");
+}
+
+static void toggle_done(int sig __maybe_unused,
+ siginfo_t *info __maybe_unused,
+ void *uc __maybe_unused)
+{
+ /* inform all threads that we're done for the day */
+ done = true;
+ gettimeofday(&end, NULL);
+ timersub(&end, &start, &runtime);
+}
+
+static void print_summary(void)
+{
+ unsigned long avg = avg_stats(&throughput_stats);
+ double stddev = stddev_stats(&throughput_stats);
+
+ printf("\nAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
+ avg, rel_stddev_stats(stddev, avg),
+ (int) runtime.tv_sec);
+}
+
+static int do_threads(struct worker *worker, struct cpu_map *cpu)
+{
+ pthread_attr_t thread_attr, *attrp = NULL;
+ cpu_set_t cpuset;
+ unsigned int i, j;
+ int ret, events = EPOLLIN;
+
+ if (oneshot)
+ events |= EPOLLONESHOT;
+ if (et)
+ events |= EPOLLET;
+
+ printinfo("starting worker/consumer %sthreads%s\n",
+ noaffinity ? "":"CPU affinity ",
+ nonblocking ? " (nonblocking)":"");
+ if (!noaffinity)
+ pthread_attr_init(&thread_attr);
+
+ for (i = 0; i < nthreads; i++) {
+ struct worker *w = &worker[i];
+
+ if (multiq) {
+ w->epollfd = epoll_create(1);
+ if (w->epollfd < 0)
+ err(EXIT_FAILURE, "epoll_create");
+
+ if (nested)
+ nest_epollfd(w);
+ }
+
+ w->tid = i;
+ w->fdmap = calloc(nfds, sizeof(int));
+ if (!w->fdmap)
+ return 1;
+
+ for (j = 0; j < nfds; j++) {
+ int efd = multiq ? w->epollfd : epollfd;
+ struct epoll_event ev;
+
+ w->fdmap[j] = eventfd(0, EFD_NONBLOCK);
+ if (w->fdmap[j] < 0)
+ err(EXIT_FAILURE, "eventfd");
+
+ ev.data.fd = w->fdmap[j];
+ ev.events = events;
+
+ ret = epoll_ctl(efd, EPOLL_CTL_ADD,
+ w->fdmap[j], &ev);
+ if (ret < 0)
+ err(EXIT_FAILURE, "epoll_ctl");
+ }
+
+ if (!noaffinity) {
+ CPU_ZERO(&cpuset);
+ CPU_SET(cpu->map[i % cpu->nr], &cpuset);
+
+ ret = pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset);
+ if (ret)
+ err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
+
+ attrp = &thread_attr;
+ }
+
+ ret = pthread_create(&w->thread, attrp, workerfn,
+ (void *)(struct worker *) w);
+ if (ret)
+ err(EXIT_FAILURE, "pthread_create");
+ }
+
+ if (!noaffinity)
+ pthread_attr_destroy(&thread_attr);
+
+ return ret;
+}
+
+static void *writerfn(void *p)
+{
+ struct worker *worker = p;
+ size_t i, j, iter;
+ const uint64_t val = 1;
+ ssize_t sz;
+ struct timespec ts = { .tv_sec = 0,
+ .tv_nsec = 500 };
+
+ printinfo("starting writer-thread: doing %s writes ...\n",
+ randomize? "random":"lineal");
+
+ for (iter = 0; !wdone; iter++) {
+ if (randomize) {
+ shuffle((void *)worker, nthreads, sizeof(*worker));
+ }
+
+ for (i = 0; i < nthreads; i++) {
+ struct worker *w = &worker[i];
+
+ if (randomize) {
+ shuffle((void *)w->fdmap, nfds, sizeof(int));
+ }
+
+ for (j = 0; j < nfds; j++) {
+ do {
+ sz = write(w->fdmap[j], &val, sizeof(val));
+ } while (!wdone && (sz < 0 && errno == EAGAIN));
+ }
+ }
+
+ nanosleep(&ts, NULL);
+ }
+
+ printinfo("exiting writer-thread (total full-loops: %zd)\n", iter);
+ return NULL;
+}
+
+static int cmpworker(const void *p1, const void *p2)
+{
+
+ struct worker *w1 = (struct worker *) p1;
+ struct worker *w2 = (struct worker *) p2;
+ return w1->tid > w2->tid;
+}
+
+int bench_epoll_wait(int argc, const char **argv)
+{
+ int ret = 0;
+ struct sigaction act;
+ unsigned int i;
+ struct worker *worker = NULL;
+ struct cpu_map *cpu;
+ pthread_t wthread;
+ struct rlimit rl, prevrl;
+
+ argc = parse_options(argc, argv, options, bench_epoll_wait_usage, 0);
+ if (argc) {
+ usage_with_options(bench_epoll_wait_usage, options);
+ exit(EXIT_FAILURE);
+ }
+
+ sigfillset(&act.sa_mask);
+ act.sa_sigaction = toggle_done;
+ sigaction(SIGINT, &act, NULL);
+
+ cpu = cpu_map__new(NULL);
+ if (!cpu)
+ goto errmem;
+
+ /* a single, main epoll instance */
+ if (!multiq) {
+ epollfd = epoll_create(1);
+ if (epollfd < 0)
+ err(EXIT_FAILURE, "epoll_create");
+
+ /*
+ * Deal with nested epolls, if any.
+ */
+ if (nested)
+ nest_epollfd(NULL);
+ }
+
+ printinfo("Using %s queue model\n", multiq ? "multi" : "single");
+ printinfo("Nesting level(s): %d\n", nested);
+
+ /* default to the number of CPUs and leave one for the writer pthread */
+ if (!nthreads)
+ nthreads = cpu->nr - 1;
+
+ worker = calloc(nthreads, sizeof(*worker));
+ if (!worker) {
+ goto errmem;
+ }
+
+ if (getrlimit(RLIMIT_NOFILE, &prevrl))
+ err(EXIT_FAILURE, "getrlimit");
+ rl.rlim_cur = rl.rlim_max = nfds * nthreads * 2 + 50;
+ printinfo("Setting RLIMIT_NOFILE rlimit from %" PRIu64 " to: %" PRIu64 "\n",
+ (uint64_t)prevrl.rlim_max, (uint64_t)rl.rlim_max);
+ if (setrlimit(RLIMIT_NOFILE, &rl) < 0)
+ err(EXIT_FAILURE, "setrlimit");
+
+ printf("Run summary [PID %d]: %d threads monitoring%s on "
+ "%d file-descriptors for %d secs.\n\n",
+ getpid(), nthreads, oneshot ? " (EPOLLONESHOT semantics)": "", nfds, nsecs);
+
+ init_stats(&throughput_stats);
+ pthread_mutex_init(&thread_lock, NULL);
+ pthread_cond_init(&thread_parent, NULL);
+ pthread_cond_init(&thread_worker, NULL);
+
+ threads_starting = nthreads;
+
+ gettimeofday(&start, NULL);
+
+ do_threads(worker, cpu);
+
+ pthread_mutex_lock(&thread_lock);
+ while (threads_starting)
+ pthread_cond_wait(&thread_parent, &thread_lock);
+ pthread_cond_broadcast(&thread_worker);
+ pthread_mutex_unlock(&thread_lock);
+
+ /*
+ * At this point the workers should be blocked waiting for read events
+ * to become ready. Launch the writer which will constantly be writing
+ * to each thread's fdmap.
+ */
+ ret = pthread_create(&wthread, NULL, writerfn,
+ (void *)(struct worker *) worker);
+ if (ret)
+ err(EXIT_FAILURE, "pthread_create");
+
+ sleep(nsecs);
+ toggle_done(0, NULL, NULL);
+ printinfo("main thread: toggling done\n");
+
+ sleep(1); /* meh */
+ wdone = true;
+ ret = pthread_join(wthread, NULL);
+ if (ret)
+ err(EXIT_FAILURE, "pthread_join");
+
+ /* cleanup & report results */
+ pthread_cond_destroy(&thread_parent);
+ pthread_cond_destroy(&thread_worker);
+ pthread_mutex_destroy(&thread_lock);
+
+ /* sort the array back before reporting */
+ if (randomize)
+ qsort(worker, nthreads, sizeof(struct worker), cmpworker);
+
+ for (i = 0; i < nthreads; i++) {
+ unsigned long t = worker[i].ops/runtime.tv_sec;
+
+ update_stats(&throughput_stats, t);
+
+ if (nfds == 1)
+ printf("[thread %2d] fdmap: %p [ %04ld ops/sec ]\n",
+ worker[i].tid, &worker[i].fdmap[0], t);
+ else
+ printf("[thread %2d] fdmap: %p ... %p [ %04ld ops/sec ]\n",
+ worker[i].tid, &worker[i].fdmap[0],
+ &worker[i].fdmap[nfds-1], t);
+ }
+
+ print_summary();
+
+ close(epollfd);
+ return ret;
+errmem:
+ err(EXIT_FAILURE, "calloc");
+}
+#endif // HAVE_EVENTFD
projects / linux-2.6-microblaze.git / commitdiff