// 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 <sys/time.h>

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

#include <err.h>

static unsigned int nthreads = 0;
static unsigned int nsecs    = 10;
/* amount of futexes per thread */
static unsigned int nfutexes = 1024;
static bool fshared = false, done = false, silent = false;
static int futex_flag = 0;

struct timeval start, end, runtime;
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;
        u_int32_t *futex;
        pthread_t thread;
        unsigned long ops;
};

static const struct option options[] = {
        OPT_UINTEGER('t', "threads", &nthreads, "Specify amount of threads"),
        OPT_UINTEGER('r', "runtime", &nsecs,    "Specify runtime (in seconds)"),
        OPT_UINTEGER('f', "futexes", &nfutexes, "Specify amount of futexes per threads"),
        OPT_BOOLEAN( 's', "silent",  &silent,   "Silent mode: do not display data/details"),
        OPT_BOOLEAN( 'S', "shared",  &fshared,  "Use shared futexes instead of private ones"),
        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 */

        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 {
                for (i = 0; i < 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 (!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(&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("%sAveraged %ld operations/sec (+- %.2f%%), total secs = %d\n",
               !silent ? "\n" : "", avg, rel_stddev_stats(stddev, avg),
               (int) runtime.tv_sec);
}

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 cpu_map *cpu;

        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 = cpu_map__new(NULL);
        if (!cpu)
                goto errmem;

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

        if (!nthreads) /* default to the number of CPUs */
                nthreads = cpu->nr;

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

        if (!fshared)
                futex_flag = FUTEX_PRIVATE_FLAG;

        printf("Run summary [PID %d]: %d threads, each operating on %d [%s] futexes for %d secs.\n\n",
               getpid(), nthreads, nfutexes, fshared ? "shared":"private", 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;
        pthread_attr_init(&thread_attr);
        gettimeofday(&start, NULL);
        for (i = 0; i < nthreads; i++) {
                worker[i].tid = i;
                worker[i].futex = calloc(nfutexes, sizeof(*worker[i].futex));
                if (!worker[i].futex)
                        goto errmem;

                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");

                ret = pthread_create(&worker[i].thread, &thread_attr, workerfn,
                                     (void *)(struct worker *) &worker[i]);
                if (ret)
                        err(EXIT_FAILURE, "pthread_create");

        }
        pthread_attr_destroy(&thread_attr);

        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);

        sleep(nsecs);
        toggle_done(0, NULL, NULL);

        for (i = 0; i < nthreads; i++) {
                ret = pthread_join(worker[i].thread, 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);

        for (i = 0; i < nthreads; i++) {
                unsigned long t = worker[i].ops/runtime.tv_sec;
                update_stats(&throughput_stats, t);
                if (!silent) {
                        if (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[nfutexes-1], t);
                }

                free(worker[i].futex);
        }

        print_summary();

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