switch-tracking.c

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// SPDX-License-Identifier: GPL-2.0
#include <sys/time.h>
#include <sys/prctl.h>
#include <errno.h>
#include <time.h>
#include <stdlib.h>

#include "parse-events.h"
#include "evlist.h"
#include "evsel.h"
#include "thread_map.h"
#include "cpumap.h"
#include "tests.h"

static int spin_sleep(void)
{
    struct timeval start, now, diff, maxtime;
    struct timespec ts;
    int err, i;

    maxtime.tv_sec = 0;
    maxtime.tv_usec = 50000;

    err = gettimeofday(&start, NULL);
    if (err)
        return err;

    /* Spin for 50ms */
    while (1) {
        for (i = 0; i < 1000; i++)
            barrier();

        err = gettimeofday(&now, NULL);
        if (err)
            return err;

        timersub(&now, &start, &diff);
        if (timercmp(&diff, &maxtime, > /* For checkpatch */))
            break;
    }

    ts.tv_nsec = 50 * 1000 * 1000;
    ts.tv_sec = 0;

    /* Sleep for 50ms */
    err = nanosleep(&ts, NULL);
    if (err == EINTR)
        err = 0;

    return err;
}

struct switch_tracking {
    struct perf_evsel *switch_evsel;
    struct perf_evsel *cycles_evsel;
    pid_t *tids;
    int nr_tids;
    int comm_seen[4];
    int cycles_before_comm_1;
    int cycles_between_comm_2_and_comm_3;
    int cycles_after_comm_4;
};

static int check_comm(struct switch_tracking *switch_tracking,
              union perf_event *event, const char *comm, int nr)
{
    if (event->header.type == PERF_RECORD_COMM &&
        (pid_t)event->comm.pid == getpid() &&
        (pid_t)event->comm.tid == getpid() &&
        strcmp(event->comm.comm, comm) == 0) {
        if (switch_tracking->comm_seen[nr]) {
            pr_debug("Duplicate comm event\n");
            return -1;
        }
        switch_tracking->comm_seen[nr] = 1;
        pr_debug3("comm event: %s nr: %d\n", event->comm.comm, nr);
        return 1;
    }
    return 0;
}

static int check_cpu(struct switch_tracking *switch_tracking, int cpu)
{
    int i, nr = cpu + 1;

    if (cpu < 0)
        return -1;

    if (!switch_tracking->tids) {
        switch_tracking->tids = calloc(nr, sizeof(pid_t));
        if (!switch_tracking->tids)
            return -1;
        for (i = 0; i < nr; i++)
            switch_tracking->tids[i] = -1;
        switch_tracking->nr_tids = nr;
        return 0;
    }

    if (cpu >= switch_tracking->nr_tids) {
        void *addr;

        addr = realloc(switch_tracking->tids, nr * sizeof(pid_t));
        if (!addr)
            return -1;
        switch_tracking->tids = addr;
        for (i = switch_tracking->nr_tids; i < nr; i++)
            switch_tracking->tids[i] = -1;
        switch_tracking->nr_tids = nr;
        return 0;
    }

    return 0;
}

static int process_sample_event(struct perf_evlist *evlist,
                union perf_event *event,
                struct switch_tracking *switch_tracking)
{
    struct perf_sample sample;
    struct perf_evsel *evsel;
    pid_t next_tid, prev_tid;
    int cpu, err;

    if (perf_evlist__parse_sample(evlist, event, &sample)) {
        pr_debug("perf_evlist__parse_sample failed\n");
        return -1;
    }

    evsel = perf_evlist__id2evsel(evlist, sample.id);
    if (evsel == switch_tracking->switch_evsel) {
        next_tid = perf_evsel__intval(evsel, &sample, "next_pid");
        prev_tid = perf_evsel__intval(evsel, &sample, "prev_pid");
        cpu = sample.cpu;
        pr_debug3("sched_switch: cpu: %d prev_tid %d next_tid %d\n",
              cpu, prev_tid, next_tid);
        err = check_cpu(switch_tracking, cpu);
        if (err)
            return err;
        /*
         * Check for no missing sched_switch events i.e. that the
         * evsel->system_wide flag has worked.
         */
        if (switch_tracking->tids[cpu] != -1 &&
            switch_tracking->tids[cpu] != prev_tid) {
            pr_debug("Missing sched_switch events\n");
            return -1;
        }
        switch_tracking->tids[cpu] = next_tid;
    }

    if (evsel == switch_tracking->cycles_evsel) {
        pr_debug3("cycles event\n");
        if (!switch_tracking->comm_seen[0])
            switch_tracking->cycles_before_comm_1 = 1;
        if (switch_tracking->comm_seen[1] &&
            !switch_tracking->comm_seen[2])
            switch_tracking->cycles_between_comm_2_and_comm_3 = 1;
        if (switch_tracking->comm_seen[3])
            switch_tracking->cycles_after_comm_4 = 1;
    }

    return 0;
}

static int process_event(struct perf_evlist *evlist, union perf_event *event,
             struct switch_tracking *switch_tracking)
{
    if (event->header.type == PERF_RECORD_SAMPLE)
        return process_sample_event(evlist, event, switch_tracking);

    if (event->header.type == PERF_RECORD_COMM) {
        int err, done = 0;

        err = check_comm(switch_tracking, event, "Test COMM 1", 0);
        if (err < 0)
            return -1;
        done += err;
        err = check_comm(switch_tracking, event, "Test COMM 2", 1);
        if (err < 0)
            return -1;
        done += err;
        err = check_comm(switch_tracking, event, "Test COMM 3", 2);
        if (err < 0)
            return -1;
        done += err;
        err = check_comm(switch_tracking, event, "Test COMM 4", 3);
        if (err < 0)
            return -1;
        done += err;
        if (done != 1) {
            pr_debug("Unexpected comm event\n");
            return -1;
        }
    }

    return 0;
}

struct event_node {
    struct list_head list;
    union perf_event *event;
    u64 event_time;
};

static int add_event(struct perf_evlist *evlist, struct list_head *events,
             union perf_event *event)
{
    struct perf_sample sample;
    struct event_node *node;

    node = malloc(sizeof(struct event_node));
    if (!node) {
        pr_debug("malloc failed\n");
        return -1;
    }
    node->event = event;
    list_add(&node->list, events);

    if (perf_evlist__parse_sample(evlist, event, &sample)) {
        pr_debug("perf_evlist__parse_sample failed\n");
        return -1;
    }

    if (!sample.time) {
        pr_debug("event with no time\n");
        return -1;
    }

    node->event_time = sample.time;

    return 0;
}

static void free_event_nodes(struct list_head *events)
{
    struct event_node *node;

    while (!list_empty(events)) {
        node = list_entry(events->next, struct event_node, list);
        list_del(&node->list);
        free(node);
    }
}

static int compar(const void *a, const void *b)
{
    const struct event_node *nodea = a;
    const struct event_node *nodeb = b;
    s64 cmp = nodea->event_time - nodeb->event_time;

    return cmp;
}

static int process_events(struct perf_evlist *evlist,
              struct switch_tracking *switch_tracking)
{
    union perf_event *event;
    unsigned pos, cnt = 0;
    LIST_HEAD(events);
    struct event_node *events_array, *node;
    struct perf_mmap *md;
    int i, ret;

    for (i = 0; i < evlist->nr_mmaps; i++) {
        md = &evlist->mmap[i];
        if (perf_mmap__read_init(md) < 0)
            continue;

        while ((event = perf_mmap__read_event(md)) != NULL) {
            cnt += 1;
            ret = add_event(evlist, &events, event);
             perf_mmap__consume(md);
            if (ret < 0)
                goto out_free_nodes;
        }
        perf_mmap__read_done(md);
    }

    events_array = calloc(cnt, sizeof(struct event_node));
    if (!events_array) {
        pr_debug("calloc failed\n");
        ret = -1;
        goto out_free_nodes;
    }

    pos = 0;
    list_for_each_entry(node, &events, list)
        events_array[pos++] = *node;

    qsort(events_array, cnt, sizeof(struct event_node), compar);

    for (pos = 0; pos < cnt; pos++) {
        ret = process_event(evlist, events_array[pos].event,
                    switch_tracking);
        if (ret < 0)
            goto out_free;
    }

    ret = 0;
out_free:
    pr_debug("%u events recorded\n", cnt);
    free(events_array);
out_free_nodes:
    free_event_nodes(&events);
    return ret;
}

int test__switch_tracking(struct test *test __maybe_unused, int subtest __maybe_unused)
{
    const char *sched_switch = "sched:sched_switch";
    struct switch_tracking switch_tracking = { .tids = NULL, };
    struct record_opts opts = {
        .mmap_pages      = UINT_MAX,
        .user_freq       = UINT_MAX,
        .user_interval       = ULLONG_MAX,
        .freq            = 4000,
        .target          = {
            .uses_mmap   = true,
        },
    };
    struct thread_map *threads = NULL;
    struct cpu_map *cpus = NULL;
    struct perf_evlist *evlist = NULL;
    struct perf_evsel *evsel, *cpu_clocks_evsel, *cycles_evsel;
    struct perf_evsel *switch_evsel, *tracking_evsel;
    const char *comm;
    int err = -1;

    threads = thread_map__new(-1, getpid(), UINT_MAX);
    if (!threads) {
        pr_debug("thread_map__new failed!\n");
        goto out_err;
    }

    cpus = cpu_map__new(NULL);
    if (!cpus) {
        pr_debug("cpu_map__new failed!\n");
        goto out_err;
    }

    evlist = perf_evlist__new();
    if (!evlist) {
        pr_debug("perf_evlist__new failed!\n");
        goto out_err;
    }

    perf_evlist__set_maps(evlist, cpus, threads);

    /* First event */
    err = parse_events(evlist, "cpu-clock:u", NULL);
    if (err) {
        pr_debug("Failed to parse event dummy:u\n");
        goto out_err;
    }

    cpu_clocks_evsel = perf_evlist__last(evlist);

    /* Second event */
    err = parse_events(evlist, "cycles:u", NULL);
    if (err) {
        pr_debug("Failed to parse event cycles:u\n");
        goto out_err;
    }

    cycles_evsel = perf_evlist__last(evlist);

    /* Third event */
    if (!perf_evlist__can_select_event(evlist, sched_switch)) {
        pr_debug("No sched_switch\n");
        err = 0;
        goto out;
    }

    err = parse_events(evlist, sched_switch, NULL);
    if (err) {
        pr_debug("Failed to parse event %s\n", sched_switch);
        goto out_err;
    }

    switch_evsel = perf_evlist__last(evlist);

    perf_evsel__set_sample_bit(switch_evsel, CPU);
    perf_evsel__set_sample_bit(switch_evsel, TIME);

    switch_evsel->system_wide = true;
    switch_evsel->no_aux_samples = true;
    switch_evsel->immediate = true;

    /* Test moving an event to the front */
    if (cycles_evsel == perf_evlist__first(evlist)) {
        pr_debug("cycles event already at front");
        goto out_err;
    }
    perf_evlist__to_front(evlist, cycles_evsel);
    if (cycles_evsel != perf_evlist__first(evlist)) {
        pr_debug("Failed to move cycles event to front");
        goto out_err;
    }

    perf_evsel__set_sample_bit(cycles_evsel, CPU);
    perf_evsel__set_sample_bit(cycles_evsel, TIME);

    /* Fourth event */
    err = parse_events(evlist, "dummy:u", NULL);
    if (err) {
        pr_debug("Failed to parse event dummy:u\n");
        goto out_err;
    }

    tracking_evsel = perf_evlist__last(evlist);

    perf_evlist__set_tracking_event(evlist, tracking_evsel);

    tracking_evsel->attr.freq = 0;
    tracking_evsel->attr.sample_period = 1;

    perf_evsel__set_sample_bit(tracking_evsel, TIME);

    /* Config events */
    perf_evlist__config(evlist, &opts, NULL);

    /* Check moved event is still at the front */
    if (cycles_evsel != perf_evlist__first(evlist)) {
        pr_debug("Front event no longer at front");
        goto out_err;
    }

    /* Check tracking event is tracking */
    if (!tracking_evsel->attr.mmap || !tracking_evsel->attr.comm) {
        pr_debug("Tracking event not tracking\n");
        goto out_err;
    }

    /* Check non-tracking events are not tracking */
    evlist__for_each_entry(evlist, evsel) {
        if (evsel != tracking_evsel) {
            if (evsel->attr.mmap || evsel->attr.comm) {
                pr_debug("Non-tracking event is tracking\n");
                goto out_err;
            }
        }
    }

    if (perf_evlist__open(evlist) < 0) {
        pr_debug("Not supported\n");
        err = 0;
        goto out;
    }

    err = perf_evlist__mmap(evlist, UINT_MAX);
    if (err) {
        pr_debug("perf_evlist__mmap failed!\n");
        goto out_err;
    }

    perf_evlist__enable(evlist);

    err = perf_evsel__disable(cpu_clocks_evsel);
    if (err) {
        pr_debug("perf_evlist__disable_event failed!\n");
        goto out_err;
    }

    err = spin_sleep();
    if (err) {
        pr_debug("spin_sleep failed!\n");
        goto out_err;
    }

    comm = "Test COMM 1";
    err = prctl(PR_SET_NAME, (unsigned long)comm, 0, 0, 0);
    if (err) {
        pr_debug("PR_SET_NAME failed!\n");
        goto out_err;
    }

    err = perf_evsel__disable(cycles_evsel);
    if (err) {
        pr_debug("perf_evlist__disable_event failed!\n");
        goto out_err;
    }

    comm = "Test COMM 2";
    err = prctl(PR_SET_NAME, (unsigned long)comm, 0, 0, 0);
    if (err) {
        pr_debug("PR_SET_NAME failed!\n");
        goto out_err;
    }

    err = spin_sleep();
    if (err) {
        pr_debug("spin_sleep failed!\n");
        goto out_err;
    }

    comm = "Test COMM 3";
    err = prctl(PR_SET_NAME, (unsigned long)comm, 0, 0, 0);
    if (err) {
        pr_debug("PR_SET_NAME failed!\n");
        goto out_err;
    }

    err = perf_evsel__enable(cycles_evsel);
    if (err) {
        pr_debug("perf_evlist__disable_event failed!\n");
        goto out_err;
    }

    comm = "Test COMM 4";
    err = prctl(PR_SET_NAME, (unsigned long)comm, 0, 0, 0);
    if (err) {
        pr_debug("PR_SET_NAME failed!\n");
        goto out_err;
    }

    err = spin_sleep();
    if (err) {
        pr_debug("spin_sleep failed!\n");
        goto out_err;
    }

    perf_evlist__disable(evlist);

    switch_tracking.switch_evsel = switch_evsel;
    switch_tracking.cycles_evsel = cycles_evsel;

    err = process_events(evlist, &switch_tracking);

    zfree(&switch_tracking.tids);

    if (err)
        goto out_err;

    /* Check all 4 comm events were seen i.e. that evsel->tracking works */
    if (!switch_tracking.comm_seen[0] || !switch_tracking.comm_seen[1] ||
        !switch_tracking.comm_seen[2] || !switch_tracking.comm_seen[3]) {
        pr_debug("Missing comm events\n");
        goto out_err;
    }

    /* Check cycles event got enabled */
    if (!switch_tracking.cycles_before_comm_1) {
        pr_debug("Missing cycles events\n");
        goto out_err;
    }

    /* Check cycles event got disabled */
    if (switch_tracking.cycles_between_comm_2_and_comm_3) {
        pr_debug("cycles events even though event was disabled\n");
        goto out_err;
    }

    /* Check cycles event got enabled again */
    if (!switch_tracking.cycles_after_comm_4) {
        pr_debug("Missing cycles events\n");
        goto out_err;
    }
out:
    if (evlist) {
        perf_evlist__disable(evlist);
        perf_evlist__delete(evlist);
    } else {
        cpu_map__put(cpus);
        thread_map__put(threads);
    }

    return err;

out_err:
    err = -1;
    goto out;
}