Round TSC calibration result towards speculated CPU base frequency

This commit is contained in:
Nekotekina 2020-04-06 22:29:53 +03:00
parent 15f01a1bf6
commit 3c3ccdbf1e
1 changed files with 9 additions and 4 deletions

View File

@ -133,7 +133,7 @@ std::string utils::get_system_info()
if (const ullong tsc_freq = get_tsc_freq())
{
fmt::append(result, " | TSC: %.06fGHz", tsc_freq / 1000000000.);
fmt::append(result, " | TSC: %.02fGHz", tsc_freq / 1000000000.);
}
else
{
@ -262,6 +262,11 @@ std::string utils::get_OS_version()
return output;
}
static constexpr ullong round_tsc(ullong val)
{
return ::rounded_div(val, 20'000'000) * 20'000'000;
}
ullong utils::get_tsc_freq()
{
const ullong cal_tsc = []() -> ullong
@ -274,7 +279,7 @@ ullong utils::get_tsc_freq()
return 0;
if (freq.QuadPart <= 9'999'999)
return freq.QuadPart * 1024;
return round_tsc(freq.QuadPart * 1024);
const ullong timer_freq = freq.QuadPart;
Sleep(1);
@ -293,7 +298,7 @@ ullong utils::get_tsc_freq()
for (int i = 0; i < samples; i++)
{
rdtsc_data[i] = __rdtsc();
rdtsc_data[i] = (_mm_lfence(), __rdtsc());
if (i > 0)
rdtsc_diff[i - 1] = rdtsc_data[i] - rdtsc_data[i - 1];
#ifdef _WIN32
@ -321,7 +326,7 @@ ullong utils::get_tsc_freq()
}
// Rounding
return acc / (samples - 1);
return round_tsc(acc / (samples - 1));
}();
return cal_tsc;