#include <sys/mman.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <fcntl.h>
#include <ctype.h>
#include <string.h>
#include <inttypes.h>

#define SIZE (5 * 1024 * 1024 * 1024)

int64_t current_time_ms() {
     struct timeval time;
     gettimeofday(&time, NULL);
     int64_t s1 = (int64_t)(time.tv_sec) * 1000;
     int64_t s2 = (time.tv_usec / 1000);
     return s1 + s2;
}

int main(int argc, char* argv[])
{
        void * buf;
        size_t size = SIZE;
        int64_t start, cost;

        buf = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, 0, 0);
        if (buf < 0 ) {
                printf("mmap failed\n");
                exit(-1);
        }

        start = current_time_ms();

        mlock(buf, size);

        cost = current_time_ms() - start;
        printf("cost: %" PRId64 " ms\n", cost);

        munmap(buf, size);

        return 0;
}