root/tools/perf/bench/evlist-open-close.c
// SPDX-License-Identifier: GPL-2.0
#include <errno.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include "bench.h"
#include "../util/debug.h"
#include "../util/stat.h"
#include "../util/evlist.h"
#include "../util/evsel.h"
#include "../util/strbuf.h"
#include "../util/record.h"
#include "../util/parse-events.h"
#include "internal/threadmap.h"
#include "internal/cpumap.h"
#include <linux/perf_event.h>
#include <linux/kernel.h>
#include <linux/time64.h>
#include <linux/string.h>
#include <subcmd/parse-options.h>

#define MMAP_FLUSH_DEFAULT 1

static int iterations = 100;
static int nr_events = 1;
static const char *event_string = "dummy";

static inline u64 timeval2usec(struct timeval *tv)
{
        return tv->tv_sec * USEC_PER_SEC + tv->tv_usec;
}

static struct record_opts opts = {
        .sample_time         = true,
        .mmap_pages          = UINT_MAX,
        .user_freq           = UINT_MAX,
        .user_interval       = ULLONG_MAX,
        .freq                = 4000,
        .target              = {
                .uses_mmap   = true,
                .default_per_cpu = true,
        },
        .mmap_flush          = MMAP_FLUSH_DEFAULT,
        .nr_threads_synthesize = 1,
        .ctl_fd              = -1,
        .ctl_fd_ack          = -1,
};

static int evlist__count_evsel_fds(struct evlist *evlist)
{
        struct evsel *evsel;
        int cnt = 0;

        evlist__for_each_entry(evlist, evsel)
                cnt += evsel->core.threads->nr * perf_cpu_map__nr(evsel->core.cpus);

        return cnt;
}

static struct evlist *bench__create_evlist(char *evstr, const char *uid_str)
{
        struct parse_events_error err;
        struct evlist *evlist = evlist__new();
        int ret;

        if (!evlist) {
                pr_err("Not enough memory to create evlist\n");
                return NULL;
        }

        parse_events_error__init(&err);
        ret = parse_events(evlist, evstr, &err);
        if (ret) {
                parse_events_error__print(&err, evstr);
                parse_events_error__exit(&err);
                pr_err("Run 'perf list' for a list of valid events\n");
                ret = 1;
                goto out_delete_evlist;
        }
        parse_events_error__exit(&err);
        if (uid_str) {
                uid_t uid = parse_uid(uid_str);

                if (uid == UINT_MAX) {
                        pr_err("Invalid User: %s", uid_str);
                        ret = -EINVAL;
                        goto out_delete_evlist;
                }
                ret = parse_uid_filter(evlist, uid);
                if (ret)
                        goto out_delete_evlist;
        }
        ret = evlist__create_maps(evlist, &opts.target);
        if (ret < 0) {
                pr_err("Not enough memory to create thread/cpu maps\n");
                goto out_delete_evlist;
        }

        evlist__config(evlist, &opts, NULL);

        return evlist;

out_delete_evlist:
        evlist__delete(evlist);
        return NULL;
}

static int bench__do_evlist_open_close(struct evlist *evlist)
{
        char sbuf[STRERR_BUFSIZE];
        int err = evlist__open(evlist);

        if (err < 0) {
                pr_err("evlist__open: %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
                return err;
        }

        err = evlist__mmap(evlist, opts.mmap_pages);
        if (err < 0) {
                pr_err("evlist__mmap: %s\n", str_error_r(errno, sbuf, sizeof(sbuf)));
                return err;
        }

        evlist__enable(evlist);
        evlist__disable(evlist);
        evlist__munmap(evlist);
        evlist__close(evlist);

        return 0;
}

static int bench_evlist_open_close__run(char *evstr, const char *uid_str)
{
        // used to print statistics only
        struct evlist *evlist = bench__create_evlist(evstr, uid_str);
        double time_average, time_stddev;
        struct timeval start, end, diff;
        struct stats time_stats;
        u64 runtime_us;
        int i, err;

        if (!evlist)
                return -ENOMEM;

        init_stats(&time_stats);

        printf("  Number of cpus:\t%d\n", perf_cpu_map__nr(evlist->core.user_requested_cpus));
        printf("  Number of threads:\t%d\n", evlist->core.threads->nr);
        printf("  Number of events:\t%d (%d fds)\n",
                evlist->core.nr_entries, evlist__count_evsel_fds(evlist));
        printf("  Number of iterations:\t%d\n", iterations);

        evlist__delete(evlist);

        for (i = 0; i < iterations; i++) {
                pr_debug("Started iteration %d\n", i);
                evlist = bench__create_evlist(evstr, uid_str);
                if (!evlist)
                        return -ENOMEM;

                gettimeofday(&start, NULL);
                err = bench__do_evlist_open_close(evlist);
                if (err) {
                        evlist__delete(evlist);
                        return err;
                }

                gettimeofday(&end, NULL);
                timersub(&end, &start, &diff);
                runtime_us = timeval2usec(&diff);
                update_stats(&time_stats, runtime_us);

                evlist__delete(evlist);
                pr_debug("Iteration %d took:\t%" PRIu64 "us\n", i, runtime_us);
        }

        time_average = avg_stats(&time_stats);
        time_stddev = stddev_stats(&time_stats);
        printf("  Average open-close took: %.3f usec (+- %.3f usec)\n", time_average, time_stddev);

        return 0;
}

static char *bench__repeat_event_string(const char *evstr, int n)
{
        char sbuf[STRERR_BUFSIZE];
        struct strbuf buf;
        int i, str_size = strlen(evstr),
            final_size = str_size * n + n,
            err = strbuf_init(&buf, final_size);

        if (err) {
                pr_err("strbuf_init: %s\n", str_error_r(err, sbuf, sizeof(sbuf)));
                goto out_error;
        }

        for (i = 0; i < n; i++) {
                err = strbuf_add(&buf, evstr, str_size);
                if (err) {
                        pr_err("strbuf_add: %s\n", str_error_r(err, sbuf, sizeof(sbuf)));
                        goto out_error;
                }

                err = strbuf_addch(&buf, i == n-1 ? '\0' : ',');
                if (err) {
                        pr_err("strbuf_addch: %s\n", str_error_r(err, sbuf, sizeof(sbuf)));
                        goto out_error;
                }
        }

        return strbuf_detach(&buf, NULL);

out_error:
        strbuf_release(&buf);
        return NULL;
}


int bench_evlist_open_close(int argc, const char **argv)
{
        const char *uid_str = NULL;
        const struct option options[] = {
                OPT_STRING('e', "event", &event_string, "event",
                           "event selector. use 'perf list' to list available events"),
                OPT_INTEGER('n', "nr-events", &nr_events,
                            "number of dummy events to create (default 1). If used with -e, it clones those events n times (1 = no change)"),
                OPT_INTEGER('i', "iterations", &iterations,
                            "Number of iterations used to compute average (default=100)"),
                OPT_BOOLEAN('a', "all-cpus", &opts.target.system_wide,
                            "system-wide collection from all CPUs"),
                OPT_STRING('C', "cpu", &opts.target.cpu_list, "cpu",
                           "list of cpus where to open events"),
                OPT_STRING('p', "pid", &opts.target.pid, "pid",
                           "record events on existing process id"),
                OPT_STRING('t', "tid", &opts.target.tid, "tid",
                           "record events on existing thread id"),
                OPT_STRING('u', "uid", &uid_str, "user", "user to profile"),
                OPT_BOOLEAN(0, "per-thread", &opts.target.per_thread, "use per-thread mmaps"),
                OPT_END()
        };
        const char *const bench_usage[] = {
                "perf bench internals evlist-open-close <options>",
                NULL
        };
        char *evstr, errbuf[BUFSIZ];
        int err;

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

        err = target__validate(&opts.target);
        if (err) {
                target__strerror(&opts.target, err, errbuf, sizeof(errbuf));
                pr_err("%s\n", errbuf);
                goto out;
        }

        /* Enable ignoring missing threads when -p option is defined. */
        opts.ignore_missing_thread = opts.target.pid;

        evstr = bench__repeat_event_string(event_string, nr_events);
        if (!evstr) {
                err = -ENOMEM;
                goto out;
        }

        err = bench_evlist_open_close__run(evstr, uid_str);

        free(evstr);
out:
        return err;
}