#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/time.h>

#define SIZE (64 << 20)

unsigned tv_msecs(struct timeval *tvs, struct timeval *tve)
{
        return (tve->tv_sec - tvs->tv_sec) * 1000 +
                (tve->tv_usec - tvs->tv_usec) / 1000;
}

int main(void)
{
        struct timeval tvs, tve;
        void *buf;
        int *p, *e, i;

        gettimeofday(&tvs, NULL);
        buf = malloc(SIZE);
        gettimeofday(&tve, NULL);
        printf("malloc took %d msecs\n", tv_msecs(&tvs, &tve));

        gettimeofday(&tvs, NULL);
        for (p = buf, e = buf + SIZE; p < e; p += 0x1000)
                i = *(volatile int*)p;
        gettimeofday(&tve, NULL);
        printf("read took %d msecs\n", tv_msecs(&tvs, &tve));

        gettimeofday(&tvs, NULL);
        for (p = buf, e = buf + SIZE; p < e; p += 0x1000)
                *(volatile int*)p = 0xaa55aa55;
        gettimeofday(&tve, NULL);
        printf("write took %d msecs\n", tv_msecs(&tvs, &tve));

        gettimeofday(&tvs, NULL);
        free(buf);
        gettimeofday(&tve, NULL);
        printf("free took %d msecs\n", tv_msecs(&tvs, &tve));

        gettimeofday(&tvs, NULL);
        buf = mmap(NULL, SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE |
                MAP_ANONYMOUS | MAP_POPULATE, -1, 0);
        gettimeofday(&tve, NULL);
        printf("mmap took %d msecs\n", tv_msecs(&tvs, &tve));

        gettimeofday(&tvs, NULL);
        munmap(buf, SIZE);
        gettimeofday(&tve, NULL);
        printf("munmap took %d msecs\n", tv_msecs(&tvs, &tve));

        return 0;
}