rdtsc时间戳

【tsc】

time stamp counter

【性能】

大概只要chrono接口的1/6时延

【测试程序】

#include <x86intrin.h>
#include <chrono>
#include <cstdio>

using namespace std::chrono;
int main(){
    u_int64_t begin = duration_cast<nanoseconds>(steady_clock::now().time_since_epoch()).count();
    for(int i=0;i<100000;i++){
        u_int64_t a = __rdtsc();
//        u_int64_t a = duration_cast<nanoseconds>(steady_clock::now().time_since_epoch()).count();
    }
    u_int64_t end = duration_cast<nanoseconds>(steady_clock::now().time_since_epoch()).count();
    printf("time_elapsed=%llu\n", end - begin);
    return 0;
}