membench.c

#define _POSIX_C_SOURCE 199309L

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>

int main(int argc, char *argv[]) {
    int megs = 100;
    size_t buflen;
    void *buf;
    struct timespec ts0, ts1;
    double diffNsec, gbps;

    if (1 < argc)
        megs = atoi(argv[1]);

    buflen = (size_t)megs * 1024 * 1024;
    if (NULL == (buf = malloc(buflen))) {
        printf("malloc failed\n");
        exit(10);
    }

    clock_gettime(CLOCK_REALTIME, &ts0); /* warming up */
    memset(buf, 0x11, buflen); /* warming up */

    clock_gettime(CLOCK_REALTIME, &ts0);
    memset(buf, 0x11, buflen);
    clock_gettime(CLOCK_REALTIME, &ts1);

    diffNsec = (ts1.tv_nsec - ts0.tv_nsec) + 1e9 * (ts1.tv_sec - ts0.tv_sec);
    gbps = buflen / diffNsec;
    printf("%f sec; %f GB/s\n", diffNsec * 1e-9, gbps);

    return 0;
}