#include <pthread.h>
#include <stdio.h>

#define LOOPS 3000000
#define NTHREADS 8
pthread_mutex_t m;
pthread_barrier_t bar;

int count;
void *thr(void *arg)
{
	int i;

	pthread_barrier_wait(&bar);
	for (i = 0; i < LOOPS; ++i) {
		pthread_mutex_lock(&m);
		count++;
		pthread_mutex_unlock(&m);
	}	
	return (NULL);
}

int main()
{
	pthread_t td[NTHREADS];
	int i;

	pthread_mutex_init(&m, NULL);
	pthread_barrier_init(&bar, NULL, NTHREADS+1);
	for (i = 0; i < NTHREADS; ++i)
		pthread_create(&td[i], NULL, thr, NULL);
	pthread_barrier_wait(&bar);
	for (i = 0; i < NTHREADS; ++i)
		pthread_join(td[i], NULL);
	pthread_mutex_destroy(&m);
	return (0);
}