testcases/kernel/sched/eas/eas_one_small_task.c

/*
 * Copyright (c) 2018 Google, Inc.
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 *
 * A single small task executes. Task placement is verified.
 */

#define _GNU_SOURCE
#include <errno.h>
#include <pthread.h>
#include <sched.h>
#include <time.h>

#include "tst_test.h"
#include "tst_safe_file_ops.h"
#include "tst_safe_pthread.h"

#include "trace_parse.h"
#include "util.h"

#define TRACE_EVENTS "sched_switch"

static int small_task_tid;

#define MIN_CORRECT_CLUSTER_PCT 90
#define BURN_SEC 5
static void *task_fn(void *arg LTP_ATTRIBUTE_UNUSED)
{
	small_task_tid = gettid();

	printf("Small task executing for %ds...\n", BURN_SEC);
	burn(BURN_SEC * USEC_PER_SEC, 1);

	return NULL;
}

static int parse_results(void)
{
	int i, pct;
	unsigned long long exec_start_us = 0;
	unsigned long long correct_us = 0;
	unsigned long long total_us = 0;
	cpu_set_t cpuset;

	if (find_cpus_with_capacity(0, &cpuset)) {
		printf("Failed to find the CPUs in the little cluster.\n");
		return -1;
	}

	for (i = 0; i < num_trace_records; i++) {
		struct trace_sched_switch *t = trace[i].event_data;
		unsigned long long segment_us;

		if (trace[i].event_type != TRACE_RECORD_SCHED_SWITCH)
			continue;

		if (t->next_pid == small_task_tid) {
			if (exec_start_us) {
				printf("Trace parse fail: double exec start\n");
				return -1;
			}
			exec_start_us = TS_TO_USEC(trace[i].ts);
			continue;
		}
		if (t->prev_pid != small_task_tid)
			continue;
		/* End of task execution segment. */
		if (!exec_start_us) {
			printf("Trace parse fail: double exec end\n");
			return -1;
		}
		segment_us = TS_TO_USEC(trace[i].ts);
		segment_us -= exec_start_us;
		exec_start_us = 0;
		if (CPU_ISSET(trace[i].cpu, &cpuset))
			correct_us += segment_us;
		total_us += segment_us;
	}

	pct = (correct_us * 100) / total_us;
	printf("Total time task scheduled: %lld usec\n"
	       "Time scheduled on a little CPU: %lld usec (%d%%)\n",
	       total_us, correct_us, pct);

	return (pct < MIN_CORRECT_CLUSTER_PCT);
}

static void run(void)
{
	pthread_t task_thread;

	tst_res(TINFO, "Minimum correct cluster time percentage: %d%%\n",
		MIN_CORRECT_CLUSTER_PCT);

	/* configure and enable tracing */
	tracefs_write("tracing_on", "0");
	tracefs_write("buffer_size_kb", "16384");
	tracefs_write("set_event", TRACE_EVENTS);
	tracefs_write("trace", "\n");
	tracefs_write("tracing_on", "1");

	SAFE_PTHREAD_CREATE(&task_thread, NULL, task_fn, NULL);
	SAFE_PTHREAD_JOIN(task_thread, NULL);

	/* disable tracing */
	tracefs_write("tracing_on", "0");
	LOAD_TRACE();

	if (parse_results())
		tst_res(TFAIL, "Small task ran too much on non-small CPUs.\n");
	else
		tst_res(TPASS, "Small task ran appropriately on small CPUs.\n");
}

static struct tst_test test = {
	.test_all = run,
	.setup = trace_setup,
	.cleanup = trace_cleanup,
};