#include <sys/param.h>
#include <sys/cpuset.h>
#include <sys/mman.h>
#include <err.h>
#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>


static void *
set_masks(void *arg)
{
	cpuset_t all, mask;
	int i, loop, rc;

	rc = cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_PID, -1, sizeof(all), &all);
	if (rc != 0)
		err(1, "getaffinity");

	/*
	 * Loop forever, setting the eligible cpu set to a randome
	 * set.
	 */
	for (loop = 0; ; loop++) {
		CPU_ZERO(&mask);
		for (i = 0; i < CHAR_BIT * sizeof(mask); i++) {
			if (!CPU_ISSET(i, &all))
				continue;
			if ((random() & 1) == 1)
				CPU_SET(i, &mask);
		}
		if (CPU_EMPTY(&mask))
			continue;
		rc = cpuset_setaffinity(CPU_LEVEL_WHICH, CPU_WHICH_PID, -1, sizeof(mask), &mask);
		if (rc != 0)
			err(1, "setaffinity");
		if ((loop & 0xFF) == 0)
			printf("Did %d loops of cpuset\n", loop);
		(void)usleep(1);
	}
	return (NULL);
}

static void *
do_syscall(void *arg)
{
	void *p;
	int loop, rc;

	for (loop = 0; ; loop++) {
		p = mmap(NULL, PAGE_SIZE, PROT_READ, MAP_ANON, -1, 0);
		if (p == MAP_FAILED)
			err(1, "mmap");
		rc = munmap(p, PAGE_SIZE);
		if (rc != 0)
			err(1, "munmap");
		if ((loop & 0xFF) == 0)
			printf("Did %d loops of syscall\n", loop);
		(void)usleep(1);
	}
	return (NULL);
}


int
main(void)
{
	pthread_t set, sys;
	void *ret;
	int rc;

	srandom(time(NULL));
	rc = pthread_create(&set, NULL, set_masks, NULL);
	if (rc != 0)
		err(1, "create set");
	rc = pthread_create(&sys, NULL, do_syscall, NULL);
	if (rc != 0)
		err(1, "create sys");

	(void)pthread_join(set, &ret);
	(void)pthread_join(sys, &ret);

	return (0);
}