[ntp:questions] Re: Windows timekeeping - sudden degradation - why?

David J Taylor david-taylor at blueyonder.co.not-this-bit.nor-this-part.uk.invalid
Wed Dec 7 16:34:58 UTC 2005

Martin Burnicki wrote:
> This points to the problems with Windows time if a multimedia
> application is started. I've mentioned this sometimes before here in
> the newsgroup, e.g. here:
> http://lists.ntp.isc.org/pipermail/questions/2005-September/006709.html
> This problem is NOT from the MM apps themselves but from the way
> Windows is keeping time, and AFAIK has been fixed by MS in SP2 for
> WinXP.
> So you won't fix the problem by using another version of ntpd. Either
> you must make sure no MM app runs at all (maybe even not in the
> background, if QT looks if updates are available), or you must have
> at least one MM app running continuously in order to have the MM
> timer set constantly set either to highest resolution or default
> resolution, but not switching between the 2 resolutions.
> If the MM timer is set constantly to high resolution then you should
> observe a little more jitter than with default resolution, but the
> large steps should go away. So as a test you just might to start
> Quicktime ant watch if the offset settles down.
> Martin


Thanks for the response.  Yes, there was something about SP2 which fixed 
the problem, and it seems to me that something I did last Friday seems to 
have undone the SP2 fix, and I can't restore whatever has been undone!  I 
suspect that QuickTime is the culprit (with me accepting the updates which 
were available), but I have no hard evidence for that.

I didn't think that changing version would help, but it seemed both polite 
to the people who suggested it, and a "good thing" to have the latest 
version in any case.

I have just started the QuickTime player, and I'll see if that makes any 

Do you know a way to check if the MM times is enabled?  I could easily 
write a small piece of code do check this and enable them as an 
experiment.  Could you perhaps send me a copy of the patch?

Your help and suggestions are very much appreciated.


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