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

Danny Mayer mayer at ntp.isc.org
Mon Dec 12 04:01:27 UTC 2005

David J Taylor wrote:
> Danny Mayer wrote:
>>David J Taylor wrote:
>>>BTW: I've now written a program to force the MM timer to have a
>>>resolution of 1ms permanently, and this seems to have fixed the
>>>problem I had.
>>This one interests me. What is it about the MM timer which makes the
>>difference? Also what's the impact of doing this versus not doing this
>>on other applications?
> Danny,
> Aside:  I've been getting direct e-mails from you which I thought should 
> have appeared on the Usenet newsgroup.  Perhaps the list reflector is not 
> working 100%?

No, it's working as designed. I have to fix your address, delete it or
get bounced mail.

> The problems seems to be as (IIRC) Martin Burnicki explained, when 
> switching between "1ms MM timer" and "normal 10/15ms timer", Windows 
> inserts some sort of "adjustment", which causes the steps we've seen.  Why 
> I only started seeing this ten days ago on the XP Pro system I don't know.

If I understand this right the change in the timer is what causes the
problem which means that the disciplining is suddenly way off. It is not
good to have the frequency change when you are trying to keep accurate
time. That would indicate that laptops which change speed when they are
unplugged or plugged in.


More information about the questions mailing list