threadtest.c

/* threadtest.c
 *		by: john stultz (johnstul@us.ibm.com)
 *		(C) Copyright IBM 2004, 2005, 2006, 2012
 *		Licensed under the GPLv2
 *
 *  To build:
 *	$ gcc threadtest.c -o threadtest -lrt
 *
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 */
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/time.h>
#include <pthread.h>
#ifdef KTEST
#include "../kselftest.h"
#else
static inline int ksft_exit_pass(void)
{
	exit(0);
}
static inline int ksft_exit_fail(void)
{
	exit(1);
}
#endif


/* serializes shared list access */
pthread_mutex_t list_lock = PTHREAD_MUTEX_INITIALIZER;
/* serializes console output */
pthread_mutex_t print_lock = PTHREAD_MUTEX_INITIALIZER;


#define MAX_THREADS 128
#define LISTSIZE 128

int done = 0;

struct timespec global_list[LISTSIZE];
int listcount = 0;


void checklist(struct timespec *list, int size)
{
	int i, j;
	struct timespec *a, *b;

	/* scan the list */
	for (i = 0; i < size-1; i++) {
		a = &list[i];
		b = &list[i+1];

		/* look for any time inconsistencies */
		if ((b->tv_sec <= a->tv_sec) &&
			(b->tv_nsec < a->tv_nsec)) {

			/* flag other threads */
			done = 1;

			/*serialize printing to avoid junky output*/
			pthread_mutex_lock(&print_lock);

			/* dump the list */
			printf("\n");
			for (j = 0; j < size; j++) {
				if (j == i)
					printf("---------------\n");
				printf("%lu:%lu\n", list[j].tv_sec, list[j].tv_nsec);
				if (j == i+1)
					printf("---------------\n");
			}
			printf("[FAILED]\n");

			pthread_mutex_unlock(&print_lock);
		}
	}
}

/* The shared thread shares a global list
 * that each thread fills while holding the lock.
 * This stresses clock syncronization across cpus.
 */
void *shared_thread(void *arg)
{
	while (!done) {
		/* protect the list */
		pthread_mutex_lock(&list_lock);

		/* see if we're ready to check the list */
		if (listcount >= LISTSIZE) {
			checklist(global_list, LISTSIZE);
			listcount = 0;
		}
		clock_gettime(CLOCK_MONOTONIC, &global_list[listcount++]);

		pthread_mutex_unlock(&list_lock);
	}
	return NULL;
}


/* Each independent thread fills in its own
 * list. This stresses clock_gettime() lock contention.
 */
void *independent_thread(void *arg)
{
	struct timespec my_list[LISTSIZE];
	int count;

	while (!done) {
		/* fill the list */
		for (count = 0; count < LISTSIZE; count++)
			clock_gettime(CLOCK_MONOTONIC, &my_list[count]);
		checklist(my_list, LISTSIZE);
	}
	return NULL;
}

#define DEFAULT_THREAD_COUNT 8
#define DEFAULT_RUNTIME 30

int main(int argc, char **argv)
{
	int thread_count, i;
	time_t start, now, runtime;
	char buf[255];
	pthread_t pth[MAX_THREADS];
	int opt;
	void *tret;
	int ret = 0;
	void *(*thread)(void *) = shared_thread;

	thread_count = DEFAULT_THREAD_COUNT;
	runtime = DEFAULT_RUNTIME;

	/* Process arguments */
	while ((opt = getopt(argc, argv, "t:n:i")) != -1) {
		switch (opt) {
		case 't':
			runtime = atoi(optarg);
			break;
		case 'n':
			thread_count = atoi(optarg);
			break;
		case 'i':
			thread = independent_thread;
			printf("using independent threads\n");
			break;
		default:
			printf("Usage: %s [-t <secs>] [-n <numthreads>] [-i]\n", argv[0]);
			printf("	-t: time to run\n");
			printf("	-n: number of threads\n");
			printf("	-i: use independent threads\n");
			return -1;
		}
	}

	if (thread_count > MAX_THREADS)
		thread_count = MAX_THREADS;


	setbuf(stdout, NULL);

	start = time(0);
	strftime(buf, 255, "%a, %d %b %Y %T %z", localtime(&start));
	printf("%s\n", buf);
	printf("Testing consistency with %i threads for %ld seconds: ", thread_count, runtime);

	/* spawn */
	for (i = 0; i < thread_count; i++)
		pthread_create(&pth[i], 0, thread, 0);

	while (time(&now) < start + runtime) {
		sleep(1);
		if (done) {
			ret = 1;
			strftime(buf, 255, "%a, %d %b %Y %T %z", localtime(&now));
			printf("%s\n", buf);
			goto out;
		}
	}
	printf("[OK]\n");
	done = 1;

out:
	/* wait */
	for (i = 0; i < thread_count; i++)
		pthread_join(pth[i], &tret);

	/* die */
	if (ret)
		ksft_exit_fail();
	return ksft_exit_pass();
}