Demo of Read Time-Stamp Counter (rdstc instruction).

rdstc-demo.c

/**
 * author: Tao He, sighingnow@gmail.com
 */

uint64_t rdtsc() {
    uint32_t lo, hi;
    __asm__ __volatile__("rdtsc" : "=a"(lo), "=d"(hi));
    return (uint64_t)hi << 32 | lo;
}

int main(int, char **) {
    printf("%llu\n", rdtsc());
    return 0;
}