sw-clock.c

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// SPDX-License-Identifier: GPL-2.0
#include <errno.h>
#include <inttypes.h>
#include <unistd.h>
#include <stdlib.h>
#include <signal.h>
#include <sys/mman.h>

#include "tests.h"
#include "util/evsel.h"
#include "util/evlist.h"
#include "util/cpumap.h"
#include "util/thread_map.h"

#define NR_LOOPS  10000000

/*
 * This test will open software clock events (cpu-clock, task-clock)
 * then check their frequency -> period conversion has no artifact of
 * setting period to 1 forcefully.
 */
static int __test__sw_clock_freq(enum perf_sw_ids clock_id)
{
    int i, err = -1;
    volatile int tmp = 0;
    u64 total_periods = 0;
    int nr_samples = 0;
    char sbuf[STRERR_BUFSIZE];
    union perf_event *event;
    struct perf_evsel *evsel;
    struct perf_evlist *evlist;
    struct perf_event_attr attr = {
        .type = PERF_TYPE_SOFTWARE,
        .config = clock_id,
        .sample_type = PERF_SAMPLE_PERIOD,
        .exclude_kernel = 1,
        .disabled = 1,
        .freq = 1,
    };
    struct cpu_map *cpus;
    struct thread_map *threads;
    struct perf_mmap *md;

    attr.sample_freq = 500;

    evlist = perf_evlist__new();
    if (evlist == NULL) {
        pr_debug("perf_evlist__new\n");
        return -1;
    }

    evsel = perf_evsel__new(&attr);
    if (evsel == NULL) {
        pr_debug("perf_evsel__new\n");
        goto out_delete_evlist;
    }
    perf_evlist__add(evlist, evsel);

    cpus = cpu_map__dummy_new();
    threads = thread_map__new_by_tid(getpid());
    if (!cpus || !threads) {
        err = -ENOMEM;
        pr_debug("Not enough memory to create thread/cpu maps\n");
        goto out_free_maps;
    }

    perf_evlist__set_maps(evlist, cpus, threads);

    cpus    = NULL;
    threads = NULL;

    if (perf_evlist__open(evlist)) {
        const char *knob = "/proc/sys/kernel/perf_event_max_sample_rate";

        err = -errno;
        pr_debug("Couldn't open evlist: %s\nHint: check %s, using %" PRIu64 " in this test.\n",
             str_error_r(errno, sbuf, sizeof(sbuf)),
             knob, (u64)attr.sample_freq);
        goto out_delete_evlist;
    }

    err = perf_evlist__mmap(evlist, 128);
    if (err < 0) {
        pr_debug("failed to mmap event: %d (%s)\n", errno,
             str_error_r(errno, sbuf, sizeof(sbuf)));
        goto out_delete_evlist;
    }

    perf_evlist__enable(evlist);

    /* collect samples */
    for (i = 0; i < NR_LOOPS; i++)
        tmp++;

    perf_evlist__disable(evlist);

    md = &evlist->mmap[0];
    if (perf_mmap__read_init(md) < 0)
        goto out_init;

    while ((event = perf_mmap__read_event(md)) != NULL) {
        struct perf_sample sample;

        if (event->header.type != PERF_RECORD_SAMPLE)
            goto next_event;

        err = perf_evlist__parse_sample(evlist, event, &sample);
        if (err < 0) {
            pr_debug("Error during parse sample\n");
            goto out_delete_evlist;
        }

        total_periods += sample.period;
        nr_samples++;
next_event:
        perf_mmap__consume(md);
    }
    perf_mmap__read_done(md);

out_init:
    if ((u64) nr_samples == total_periods) {
        pr_debug("All (%d) samples have period value of 1!\n",
             nr_samples);
        err = -1;
    }

out_free_maps:
    cpu_map__put(cpus);
    thread_map__put(threads);
out_delete_evlist:
    perf_evlist__delete(evlist);
    return err;
}

int test__sw_clock_freq(struct test *test __maybe_unused, int subtest __maybe_unused)
{
    int ret;

    ret = __test__sw_clock_freq(PERF_COUNT_SW_CPU_CLOCK);
    if (!ret)
        ret = __test__sw_clock_freq(PERF_COUNT_SW_TASK_CLOCK);

    return ret;
}