From 121dd9ea0116de3e79a4903a84018190c595e2b6 Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Tue, 6 Nov 2018 07:22:25 -0800 Subject: [PATCH] perf bench: Add epoll parallel epoll_wait benchmark This program benchmarks concurrent epoll_wait(2) for file descriptors that are monitored with with EPOLLIN along various semantics, by a single epoll instance. Such conditions can be found when using single/combined or multiple queuing when load balancing. 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. Full details in the start of the C file. Committer testing: # perf bench Usage: perf bench [] [] # List of all available benchmark collections: sched: Scheduler and IPC benchmarks mem: Memory access benchmarks numa: NUMA scheduling and MM benchmarks futex: Futex stressing benchmarks epoll: Epoll stressing benchmarks all: All benchmarks # perf bench epoll # List of available benchmarks for collection 'epoll': wait: Benchmark epoll concurrent epoll_waits all: Run all futex benchmarks # perf bench epoll wait # Running 'epoll/wait' benchmark: Run summary [PID 19295]: 3 threads monitoring on 64 file-descriptors for 8 secs. [thread 0] fdmap: 0xdaa650 ... 0xdaa74c [ 328241 ops/sec ] [thread 1] fdmap: 0xdaa900 ... 0xdaa9fc [ 351695 ops/sec ] [thread 2] fdmap: 0xdaabb0 ... 0xdaacac [ 381423 ops/sec ] Averaged 353786 operations/sec (+- 4.35%), total secs = 8 # Committer notes: Fix the build on debian:experimental-x-mips, debian:experimental-x-mipsel and others: CC /tmp/build/perf/bench/epoll-wait.o bench/epoll-wait.c: In function 'writerfn': bench/epoll-wait.c:399:12: error: format '%ld' expects argument of type 'long int', but argument 2 has type 'size_t' {aka 'unsigned int'} [-Werror=format=] printinfo("exiting writer-thread (total full-loops: %ld)\n", iter); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~ bench/epoll-wait.c:86:31: note: in definition of macro 'printinfo' do { if (__verbose) { printf(fmt, ## arg); fflush(stdout); } } while (0) ^~~ cc1: all warnings being treated as errors Signed-off-by: Davidlohr Bueso Tested-by: Arnaldo Carvalho de Melo Cc: Andrew Morton Cc: Davidlohr Bueso Cc: Jason Baron Link: http://lkml.kernel.org/r/20181106152226.20883-2-dave@stgolabs.net Link: http://lkml.kernel.org/r/20181106182349.thdkpvshkna5vd7o@linux-r8p5> [ Applied above fixup as per Davidlohr's request ] [ Use inttypes.h to print rlim_t fields, fixing the build on Alpine Linux / musl libc ] [ Check if eventfd() is available, i.e. if HAVE_EVENTFD is defined ] Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/Documentation/perf-bench.txt | 7 + tools/perf/bench/Build | 2 + tools/perf/bench/bench.h | 2 + tools/perf/bench/epoll-wait.c | 540 ++++++++++++++++++++++++++++++++ tools/perf/builtin-bench.c | 12 + 5 files changed, 563 insertions(+) create mode 100644 tools/perf/bench/epoll-wait.c diff --git a/tools/perf/Documentation/perf-bench.txt b/tools/perf/Documentation/perf-bench.txt index 34750fc32714..3a6b2e73b2e8 100644 --- a/tools/perf/Documentation/perf-bench.txt +++ b/tools/perf/Documentation/perf-bench.txt @@ -58,6 +58,9 @@ SUBSYSTEM 'futex':: Futex stressing benchmarks. +'epoll':: + Eventpoll (epoll) stressing benchmarks. + 'all':: All benchmark subsystems. @@ -203,6 +206,10 @@ Suite for evaluating requeue calls. *lock-pi*:: Suite for evaluating futex lock_pi calls. +SUITES FOR 'epoll' +~~~~~~~~~~~~~~~~~~ +*wait*:: +Suite for evaluating concurrent epoll_wait calls. SEE ALSO -------- diff --git a/tools/perf/bench/Build b/tools/perf/bench/Build index eafce1a130a1..2bb79b542d53 100644 --- a/tools/perf/bench/Build +++ b/tools/perf/bench/Build @@ -7,6 +7,8 @@ perf-y += futex-wake-parallel.o perf-y += futex-requeue.o perf-y += futex-lock-pi.o +perf-y += epoll-wait.o + perf-$(CONFIG_X86_64) += mem-memcpy-x86-64-lib.o perf-$(CONFIG_X86_64) += mem-memcpy-x86-64-asm.o perf-$(CONFIG_X86_64) += mem-memset-x86-64-asm.o diff --git a/tools/perf/bench/bench.h b/tools/perf/bench/bench.h index 8299c76046cd..6e1f091ced96 100644 --- a/tools/perf/bench/bench.h +++ b/tools/perf/bench/bench.h @@ -38,6 +38,8 @@ int bench_futex_requeue(int argc, const char **argv); /* pi futexes */ int bench_futex_lock_pi(int argc, const char **argv); +int bench_epoll_wait(int argc, const char **argv); + #define BENCH_FORMAT_DEFAULT_STR "default" #define BENCH_FORMAT_DEFAULT 0 #define BENCH_FORMAT_SIMPLE_STR "simple" diff --git a/tools/perf/bench/epoll-wait.c b/tools/perf/bench/epoll-wait.c new file mode 100644 index 000000000000..5a11534e96a0 --- /dev/null +++ b/tools/perf/bench/epoll-wait.c @@ -0,0 +1,540 @@ +// 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 +#include + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "../util/stat.h" +#include +#include "bench.h" +#include "cpumap.h" + +#include + +#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 ", + 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 diff --git a/tools/perf/builtin-bench.c b/tools/perf/builtin-bench.c index 17a6bcd01aa6..55efd23c3efb 100644 --- a/tools/perf/builtin-bench.c +++ b/tools/perf/builtin-bench.c @@ -14,6 +14,7 @@ * mem ... memory access performance * numa ... NUMA scheduling and MM performance * futex ... Futex performance + * epoll ... Event poll performance */ #include "perf.h" #include "util/util.h" @@ -67,6 +68,14 @@ static struct bench futex_benchmarks[] = { { NULL, NULL, NULL } }; +#ifdef HAVE_EVENTFD +static struct bench epoll_benchmarks[] = { + { "wait", "Benchmark epoll concurrent epoll_waits", bench_epoll_wait }, + { "all", "Run all futex benchmarks", NULL }, + { NULL, NULL, NULL } +}; +#endif // HAVE_EVENTFD + struct collection { const char *name; const char *summary; @@ -80,6 +89,9 @@ static struct collection collections[] = { { "numa", "NUMA scheduling and MM benchmarks", numa_benchmarks }, #endif {"futex", "Futex stressing benchmarks", futex_benchmarks }, +#ifdef HAVE_EVENTFD + {"epoll", "Epoll stressing benchmarks", epoll_benchmarks }, +#endif { "all", "All benchmarks", NULL }, { NULL, NULL, NULL } }; -- 2.11.0