#include <limits.h>
#include <pthread.h>
#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <asm/msr.h>

unsigned long long old;
unsigned long min_diff = LONG_MAX, max_diff = 0;
unsigned long long sum_diff = 0;
unsigned int count = 0;
unsigned int start = 0;

unsigned int distr[100];

void *thread(void *data)
{
	long long prev, diff;
	unsigned int k = (unsigned int) data;
	volatile int *s = &start;
	while (!*s);
	while (count < 1000000) {
		prev = old;
		rdtscll(old);
		diff = old - prev;
		if (diff < min_diff) {
			min_diff = diff;
		}
		if (diff > max_diff) {
			max_diff = diff;
		}
		sum_diff += diff;
		count++;
		distr[k]++;
		sched_yield();
	}
	return 0;
}

int main(int argc, char **argv)
{
	int num_threads = atoi(argv[1]);
	pthread_t threads[num_threads];
	int k;
	for (k = 0; k < num_threads; ++k)
		pthread_create(&threads[k], NULL, thread, (void*) k);
	rdtscll(old);
	start = 1;
	for (k = 0; k < num_threads; ++k) {
		pthread_join(threads[k], 0);
		printf("%d: %d iterations\n", k, distr[k]);
	}
	printf("min=%ld max=%ld avg=%lld\n", min_diff, max_diff, sum_diff / count);
	return 0;
}