Re: [boost] Low-level precision timer proposal

From: Peter Dimov (pdimov_at_[hidden])
Date: 2006-05-15 15:09:43

Silex wrote:
>> The problem with QueryPerformanceCounter is that
>> QueryPerformanceFrequency is not (AFAIK) required to return the same
>> value every time. It may be CPU clock based, and a low power CPU can
>> vary its frequency depending on load.
>
> No, "the frequency cannot change while the system is running."
> (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winui/winui/windowsuserinterface/windowing/timers/timerreference/timerfunctions/queryperformancefrequency.asp)

You are right, a variable frequency is explicitly disallowed in the 
documentation now. Most chipset bugs that affected QPC also don't seem to be 
an issue nowadays.