#include <stdio.h>
#include <sys/mman.h>
#include <unistd.h>

#include "omp.h"

#ifndef BUF_SIZE
#define BUF_SIZE (64 * 1024 * 1024)
#endif

#ifndef PAGE_SIZE
#define PAGE_SIZE (4 * 1024)
#endif

#ifdef POPULATE_VIA_MMAP
#define MMAP_FLAGS (MAP_ANONYMOUS | MAP_PRIVATE | MAP_POPULATE)
#else
#define MMAP_FLAGS (MAP_ANONYMOUS | MAP_PRIVATE)
#endif

int main(int argc, char **argv)
{
#pragma omp parallel
	{
	}

	double t0 = omp_get_wtime();
#pragma omp parallel
	{
		int i;
		for (i = 0; i < 10; i++) {
			char *p = mmap(NULL, BUF_SIZE,
				PROT_READ | PROT_WRITE, MMAP_FLAGS, -1, 0);
#ifdef POPULATE_VIA_LOOP
			size_t j;
			for (j = 0; j < BUF_SIZE; j += PAGE_SIZE)
				p[j] = 0;
#endif
		}
	}
	double t1 = omp_get_wtime();
	printf("%d\t%f\n", omp_get_max_threads(), t1 - t0);

	return 0;
}