[ntp:questions] Windows-8 improved timekeeping

David Taylor david-taylor at blueyonder.co.uk.invalid
Fri Dec 28 09:32:23 UTC 2012

Just for interest, I've provided a performance snapshot of a recent NTP 
running on Windows-8, with both Internet-only and LAN-based servers.

When running off just Internet (WAN) servers, Windows-8 shows an 
averaged jitter of less than a millisecond, perhaps 0.4 - 0.6 
millisecond after the initial transient has settled down.  Windows-7, by 
comparison, shows 3 - 9.5 milliseconds averaged jitter.  Likely the 
improvement is due to the use of the new precise-time instruction in 
Windows-8, which is used by recent development releases of NTP.

When running off the LAN, averaged jitter is around 40-80 microseconds 
in another Windows-8 system.


There still remains an issue with Windows-8 and the resolution of the 
timer adjustment, which allows fine adjustments and reports them back 
(IIRC), but internally only makes coarser adjustments.  Yes, these 
results are not as good as you might expect with FreeBSD or Linux, but 
it does seem that Windows-8 timekeeping is an improvement over Windows-7.

I hope that's of some interest.
Web: http://www.satsignal.eu

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