Testing GetTickCount64() vs GetMicrosecondCount() - page 3

Dominik Egert · 2022-05-27T23:19:03.0000000Z

A simple attempt to synchronize the OnTimer() call to TimeLocal to be called at around the next second has revealed a question, I cannot wrap my head around. So I tried to analyze the behaviour and found that GetTickCount64() and GetMicrosecondCount() give confusing results, as can be seen in the screenshot. Here is the code to reproduce the output: //+------------------------------------------------------------------+ //| Expert timer function | //+------------------------------------------------------------------+ void OnTimer () { printf("OnTimer()"); ulong enter = GetTickCount64 (); ulong enter_mc = GetMicrosecondCount (); ulong mics = GetMicrosecondCount (); while (mics + 500000 > GetMicrosecondCount ()); //Sleep(500); mics = GetMicrosecondCount () - mics; ulong exit_mc = GetMicrosecondCount (); ulong exit = GetTickCount64 (); printf ( "Exec time: %llu; %llu" , exit - enter, exit_mc - enter_mc); // Return return ; } Can anyone explain why there are such differences? I would expect some drift, maybe even up to a millisecond, but over 10 milliseconds? how is that possible? I consider this to be a bug.