// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2013  Davidlohr Bueso <davidlohr@hp.com>
 *
 * futex-hash: Stress the hell out of the Linux kernel futex uaddr hashing.
 *
 * This program is particularly useful for measuring the kernel's futex hash
 * table/function implementation. In order for it to make sense, use with as
 * many threads and futexes as possible.
 */

/* For the CLR_() macros */
#include <string.h>
#include <pthread.h>

#include <errno.h>
#include <signal.h>
#include <stdlib.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/zalloc.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <sys/prctl.h>
#include <perf/cpumap.h>

#include "../util/mutex.h"
#include "../util/stat.h"
#include <subcmd/parse-options.h>
#include "bench.h"
#include "futex.h"

#include <err.h>

static bool done = false;
static int futex_flag = 0;

struct timeval bench__start, bench__end, bench__runtime;
static struct mutex thread_lock;
static unsigned int threads_starting;
static struct stats throughput_stats;
static struct cond thread_parent, thread_worker;

struct worker {
        int tid;
        u_int32_t *futex;
        pthread_t thread;
        unsigned long ops;
};

static struct bench_futex_parameters params = {
        .nfutexes = 1024,
        .runtime  = 10,
        .nbuckets = -1,
};

static const struct option options[] = {
        OPT_INTEGER( 'b', "buckets", &params.nbuckets, "Specify amount of hash buckets"),
        OPT_UINTEGER('t', "threads", &params.nthreads, "Specify amount of threads"),
        OPT_UINTEGER('r', "runtime", &params.runtime, "Specify runtime (in seconds)"),
        OPT_UINTEGER('f', "futexes", &params.nfutexes, "Specify amount of futexes per threads"),
        OPT_BOOLEAN( 's', "silent",  &params.silent, "Silent mode: do not display data/details"),
        OPT_BOOLEAN( 'S', "shared",  &params.fshared, "Use shared futexes instead of private ones"),
        OPT_BOOLEAN( 'm', "mlockall", &params.mlockall, "Lock all current and future memory"),
        OPT_END()
};

static const char * const bench_futex_hash_usage[] = {
        "perf bench futex hash <options>",
        NULL
};

static void *workerfn(void *arg)
{
        int ret;
        struct worker *w = (struct worker *) arg;
        unsigned int i;
        unsigned long ops = w->ops; /* avoid cacheline bouncing */

        mutex_lock(&thread_lock);
        threads_starting--;
        if (!threads_starting)
                cond_signal(&thread_parent);
        cond_wait(&thread_worker, &thread_lock);
        mutex_unlock(&thread_lock);

        do {
                for (i = 0; i < params.nfutexes; i++, ops++) {
                        /*
                         * We want the futex calls to fail in order to stress
                         * the hashing of uaddr and not measure other steps,
                         * such as internal waitqueue handling, thus enlarging
                         * the critical region protected by hb->lock.
                         */
                        ret = futex_wait(&w->futex[i], 1234, NULL, futex_flag);
                        if (!params.silent &&
                            (!ret || errno != EAGAIN || errno != EWOULDBLOCK))
                                warn("Non-expected futex return call");
                }
        }  while (!done);

        w->ops = ops;
        return NULL;
}

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(&bench__end, NULL);
        timersub(&bench__end, &bench__start, &bench__runtime);
}

static void print_summary(void)
{
        unsigned long avg = avg_stats(&throughput_stats);
        double stddev = stddev_stats(&throughput_stats);

        printf("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
               !params.silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg),
               (int)bench__runtime.tv_sec);
        futex_print_nbuckets(&params);
}

int bench_futex_hash(int argc, const char **argv)
{
        int ret = 0;
        cpu_set_t *cpuset;
        struct sigaction act;
        unsigned int i;
        pthread_attr_t thread_attr;
        struct worker *worker = NULL;
        struct perf_cpu_map *cpu;
        int nrcpus;
        size_t size;

        argc = parse_options(argc, argv, options, bench_futex_hash_usage, 0);
        if (argc) {
                usage_with_options(bench_futex_hash_usage, options);
                exit(EXIT_FAILURE);
        }

        cpu = perf_cpu_map__new_online_cpus();
        if (!cpu)
                goto errmem;

        memset(&act, 0, sizeof(act));
        sigfillset(&act.sa_mask);
        act.sa_sigaction = toggle_done;
        sigaction(SIGINT, &act, NULL);

        if (params.mlockall) {
                if (mlockall(MCL_CURRENT | MCL_FUTURE))
                        err(EXIT_FAILURE, "mlockall");
        }

        if (!params.nthreads) /* default to the number of CPUs */
                params.nthreads = perf_cpu_map__nr(cpu);

        worker = calloc(params.nthreads, sizeof(*worker));
        if (!worker)
                goto errmem;

        if (!params.fshared)
                futex_flag = FUTEX_PRIVATE_FLAG;
        futex_set_nbuckets_param(&params);

        printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n",
               getpid(), params.nthreads, params.nfutexes, params.fshared ? "shared":"private", params.runtime);

        init_stats(&throughput_stats);
        mutex_init(&thread_lock);
        cond_init(&thread_parent);
        cond_init(&thread_worker);

        threads_starting = params.nthreads;
        pthread_attr_init(&thread_attr);
        gettimeofday(&bench__start, NULL);

        nrcpus = cpu__max_cpu().cpu;
        cpuset = CPU_ALLOC(nrcpus);
        BUG_ON(!cpuset);
        size = CPU_ALLOC_SIZE(nrcpus);

        for (i = 0; i < params.nthreads; i++) {
                worker[i].tid = i;
                worker[i].futex = calloc(params.nfutexes, sizeof(*worker[i].futex));
                if (!worker[i].futex)
                        goto errmem;

                CPU_ZERO_S(size, cpuset);

                CPU_SET_S(perf_cpu_map__cpu(cpu, i % perf_cpu_map__nr(cpu)).cpu, size, cpuset);
                ret = pthread_attr_setaffinity_np(&thread_attr, size, cpuset);
                if (ret) {
                        CPU_FREE(cpuset);
                        err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
                }
                ret = pthread_create(&worker[i].thread, &thread_attr, workerfn,
                                     (void *)(struct worker *) &worker[i]);
                if (ret) {
                        CPU_FREE(cpuset);
                        err(EXIT_FAILURE, "pthread_create");
                }

        }
        CPU_FREE(cpuset);
        pthread_attr_destroy(&thread_attr);

        mutex_lock(&thread_lock);
        while (threads_starting)
                cond_wait(&thread_parent, &thread_lock);
        cond_broadcast(&thread_worker);
        mutex_unlock(&thread_lock);

        sleep(params.runtime);
        toggle_done(0, NULL, NULL);

        for (i = 0; i < params.nthreads; i++) {
                ret = pthread_join(worker[i].thread, NULL);
                if (ret)
                        err(EXIT_FAILURE, "pthread_join");
        }

        /* cleanup & report results */
        cond_destroy(&thread_parent);
        cond_destroy(&thread_worker);
        mutex_destroy(&thread_lock);

        for (i = 0; i < params.nthreads; i++) {
                unsigned long t = bench__runtime.tv_sec > 0 ?
                        worker[i].ops / bench__runtime.tv_sec : 0;
                update_stats(&throughput_stats, t);
                if (!params.silent) {
                        if (params.nfutexes == 1)
                                printf("[thread %2d] futex: %p [ %ld ops/sec ]\n",
                                       worker[i].tid, &worker[i].futex[0], t);
                        else
                                printf("[thread %2d] futexes: %p ... %p [ %ld ops/sec ]\n",
                                       worker[i].tid, &worker[i].futex[0],
                                       &worker[i].futex[params.nfutexes-1], t);
                }

                zfree(&worker[i].futex);
        }

        print_summary();

        free(worker);
        free(cpu);
        return ret;
errmem:
        err(EXIT_FAILURE, "calloc");
}