Simple cache-size detecting test

cache_torture.c

#include <stdio.h>
#include <malloc.h>
#include <sys/time.h>
#include <assert.h>

#define TIMER(t) double (t) = 0.0

#define START_TIMER(t) do { \
    struct timeval start; \
    gettimeofday(&start, 0); \
    (t) = (double) start.tv_sec + (double) start.tv_usec / 1e6; \
} while (0)

#define STOP_TIMER(t) do { \
    struct timeval stop;\
    gettimeofday(&stop, 0);    \
    (t) = (double) stop.tv_sec + (double) stop.tv_usec / 1e6 - (t);\
} while (0)

#define MS(t) ((t) * 1e3)

const size_t CAHCHELINE_SIZE = 64;

int main(int argc, char **argv)
{
    const size_t MAX_DATA_SIZE = 1024 * 1024 * 512;
    const size_t ACCESS_TIMES = 1024 * 1024 * 64;

    char *data = memalign(CAHCHELINE_SIZE, MAX_DATA_SIZE);
    assert(data);

    for (size_t data_size = 256; data_size < MAX_DATA_SIZE; data_size *= 2) {
        printf("%zu", data_size);

        TIMER(t); START_TIMER(t);
        for (size_t i = 0; i < ACCESS_TIMES; ++i) {
            size_t j = (i * 268435813L) % data_size;
            data[j] = data[j] * 2;
        }
        STOP_TIMER(t);

        printf("\t%.8f\n", t);
    }

    free(data);
    return 0;
}