----- Original Message ----- From: "Martin Slater" <mslater@hellinc.net>
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winui/winui...
watch the line wrap. QueryPerformanceCounter uses the CPU clock and is not per task but system wide.
Thanks.
Can you point me to documentation which supports your assertion?
The only problem with QueryPerformanceCounter() is that it can "jump" on some chipsets.
I believe this problem is perhaps not restricted to QueryPerformanceCounter() but to any counter counting mechanism, as the problem is at the chipset level not the API level.
No, there is a very particualar problem relating to QueryPerformanceCounter() on some (old?) chipsets the can cause it go backwards in time and wrap after approximately 20 minutes. I reported this to microsoft some years ago and it was confirmed an issue. (at the time only happened to me on one particualar celeron / motherboard configuration). By backwards in time I mean you could call the counter in a loop and have a reported time earlier than one got the previous iteration.
Really? That is different than the issue documentation I found at http://support.microsoft.com/default.aspx?scid=kb;EN-US;q274323 which stats that the QueryPerformanceCounter() can jump *ahead* a few seconds. I wonder if the status of the issue has changed to this new version or the documentation just sux.
This bit me on commercial code and I resorted to timeBeginPeriod(1); timeGetTime(); instead with no issues.
Martin
Thanks for your help Martin, Christopher