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

David J Taylor david-taylor at blueyonder.co.not-this-bit.nor-this-part.uk.invalid
Sun Dec 4 17:20:41 UTC 2005


Eugen COCA wrote:
> Looking at the graphs from the Odin server I wonder how is the offset
> measured (relative to what server). The actual behaviour is more
> realistic for a "heavy interactive" PC than the old ones (with only
> several milliseconds error). A Win2k server with no user interraction
> have a 5 to 20 ms offset errors (depending on the network delays, room
> temperature (!!!), mains voltage (!!!), and others). With moderate
> user interraction the errors are between 30 and 100ms and with heavy
> user interractions the errors where sometimes more than 300-800ms.
> Very strange, on a Linux Mandrake systems (dual processor, a lot of
> RAM) on periods with high CPU loads the offsets where more than
> 500-800ms.
>
> I'm really interested with your problem and the possible cause !

>From the graphs here:

  http://www.david-taylor.myby.co.uk/mrtg/daily_ntp.html

you can click on a PC and see the daily, weekly, monthly and yearly 
summaries.

Bacchus is a very old PC (by today's standards) and does show variation 
with temperature, but not more than 10 - 20ms per day.  Apart from that, 
it is a solid timekeeper.

Hermes runs Windows 2000 workstation and is absolutely solid.

Odin, until just after lunch on Friday, was fine.  It can't have been the 
introduction of the leap-second bit, can it?  I don't know how long that 
bit has been there.

Stamsund, Windows 2000 workstation, has always been variable but, you can 
see that when it is not used (during the night, all Thursday), it doesn't 
show jitter, but recovers towards a zero offset.  On the other hand, Odin 
has shown signs of jitter even during the night.  (Both Odin and Stamsund 
run a similar set of background tasks).

Yes, I would love to know what the problem is as well!

David 





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