switch-tracking.c

// SPDX-License-Identifier: GPL-2.0
#include <sys/time.h>
#include <sys/prctl.h>
#include <errno.h>
#include <limits.h>
#include <time.h>
#include <stdlib.h>
#include <linux/zalloc.h>
#include <linux/err.h>
#include <perf/cpumap.h>
#include <perf/evlist.h>
#include <perf/mmap.h>

#include "debug.h"
#include "parse-events.h"
#include "evlist.h"
#include "evsel.h"
#include "thread_map.h"
#include "record.h"
#include "tests.h"
#include "util/mmap.h"
#include "util/sample.h"
#include "pmus.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 evsel *switch_evsel;
	struct 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 evlist *evlist,
				union perf_event *event,
				struct switch_tracking *switch_tracking)
{
	struct perf_sample sample;
	struct evsel *evsel;
	pid_t next_tid, prev_tid;
	int cpu, err;

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

	evsel = evlist__id2evsel(evlist, sample.id);
	if (evsel == switch_tracking->switch_evsel) {
		next_tid = evsel__intval(evsel, &sample, "next_pid");
		prev_tid = 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->core.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 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 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 (evlist__parse_sample(evlist, event, &sample)) {
		pr_debug("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_init(&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 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 mmap *md;
	int i, ret;

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

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

	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;
}

/**
 * test__switch_tracking - test using sched_switch and tracking events.
 *
 * This function implements a test that checks that sched_switch events and
 * tracking events can be recorded for a workload (current process) using the
 * evsel->core.system_wide and evsel->tracking flags (respectively) with other events
 * sometimes enabled or disabled.
 */
static int test__switch_tracking(struct test_suite *test __maybe_unused, int subtest __maybe_unused)
{
	const char *sched_switch = "sched:sched_switch";
	const char *cycles = "cycles:u";
	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 perf_thread_map *threads = NULL;
	struct perf_cpu_map *cpus = NULL;
	struct evlist *evlist = NULL;
	struct evsel *evsel, *cpu_clocks_evsel, *cycles_evsel;
	struct 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 = perf_cpu_map__new(NULL);
	if (!cpus) {
		pr_debug("perf_cpu_map__new failed!\n");
		goto out_err;
	}

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

	perf_evlist__set_maps(&evlist->core, cpus, threads);

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

	cpu_clocks_evsel = evlist__last(evlist);

	/* Second event */
	err = parse_event(evlist, cycles);
	if (err) {
		pr_debug("Failed to parse event %s\n", cycles);
		goto out_err;
	}

	cycles_evsel = evlist__last(evlist);

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

	switch_evsel = evlist__add_sched_switch(evlist, true);
	if (IS_ERR(switch_evsel)) {
		err = PTR_ERR(switch_evsel);
		pr_debug("Failed to create event %s\n", sched_switch);
		goto out_err;
	}

	switch_evsel->immediate = true;

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

	evsel__set_sample_bit(cycles_evsel, CPU);
	evsel__set_sample_bit(cycles_evsel, TIME);

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

	tracking_evsel = evlist__last(evlist);

	evlist__set_tracking_event(evlist, tracking_evsel);

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

	evsel__set_sample_bit(tracking_evsel, TIME);

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

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

	/* Check tracking event is tracking */
	if (!tracking_evsel->core.attr.mmap || !tracking_evsel->core.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->core.attr.mmap || evsel->core.attr.comm) {
				pr_debug("Non-tracking event is tracking\n");
				goto out_err;
			}
		}
	}

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

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

	evlist__enable(evlist);

	err = 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 = 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 = 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;
	}

	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) {
		evlist__disable(evlist);
		evlist__delete(evlist);
	}
	perf_cpu_map__put(cpus);
	perf_thread_map__put(threads);

	return err;

out_err:
	err = -1;
	goto out;
}

DEFINE_SUITE("Track with sched_switch", switch_tracking);