time_vdso

#include <time.h>

/*
 * $ time ./time
 *
 * real    0m6.183s
 * user    0m1.225s
 * sys     0m4.959s
 * $ export TZ=Europe/Rome
 * $ time ./time
 *
 * real    0m0.444s
 * user    0m0.443s
 * sys     0m0.000s
 */

int main(int argc, char *argv[])
{
    int i = 0;
    time_t timep;

    for (i = 0; i < 5000000; i++) {
        time(&timep);
        localtime(&timep);
    }

    return 0;
}