WhyCan Forum(哇酷开发者社区)

#include <string.h>
#include <sys/time.h>
#include <stdlib.h>
#include <time.h>
#include <stdint.h>
#include <stdio.h>

#define ONE_MILLION   1000000
#define MEM_TEST_SIZE (100 * ONE_MILLION)

int main(int argc, char* argv[])
{
        if (argc < 2)
        {
                printf("usage: %s n (test n mega bytes)\n", argv[0]);
                exit(-1);
        }

        int n = abs(atoi(argv[1]));

        printf("now test copy %dM bytes.\n", n);

        uint8_t *src = (uint8_t *)malloc(n * ONE_MILLION);
        uint8_t *dst = (uint8_t *)malloc(n * ONE_MILLION);

        if(!src || !dst)
        {
                printf("alloc memory error!\n");
                exit(-2);
        }

        struct  timeval time_start;
        struct  timeval time_end;

        gettimeofday(&time_start,NULL);
        memcpy(dst, src, (n * ONE_MILLION));
        gettimeofday(&time_end,NULL);
        printf("calculate time: %ld us \n",
                (ONE_MILLION * time_end.tv_sec + time_end.tv_usec)-(ONE_MILLION*time_start.tv_sec + time_start.tv_usec)
              );

        free(dst);
        free(src);
        return 0;
 }

$
$ ./memtest 1
now test copy 1M bytes.
calculate time: 665 us
$
$ ./memtest 10
now test copy 10M bytes.
calculate time: 6692 us
$
$ ./memtest 100
now test copy 100M bytes.
calculate time: 67354 us