Measuring the CPU frequency scaling effect
- by Bryan Fok
Recently I am trying to measure the effect of the cpu scaling. Is it accurate if I use this clock to measure it?
template<std::intmax_t clock_freq>
struct rdtsc_clock {
typedef unsigned long long rep;
typedef std::ratio<1, clock_freq> period;
typedef std::chrono::duration<rep, period> duration;
typedef std::chrono::time_point<rdtsc_clock> time_point;
static const bool is_steady = true;
static time_point now() noexcept
{
unsigned lo, hi;
asm volatile("rdtsc" : "=a" (lo), "=d" (hi));
return time_point(duration(static_cast<rep>(hi) << 32 | lo));
}
};
Update:
According to the comment from my another post, I believe redtsc cannot use for measure the effect of cpu frequency scaling because the counter from the redtsc does not affected by the CPU frequency, am i right?
