[ntp:questions] Re: ntpd PLL and clock overshoot

Terje Mathisen terje.mathisen at hda.hydro.com
Wed Oct 18 13:52:02 UTC 2006


Martin Burnicki wrote:
> Then ntpd starts to correct the initial offset properly in less than 300
> seconds. This looks like it was going to converge properly. However,
> unfortunately at a 10 ms offset the filter algorithm seems to switch and
> the following correction is still very poor compared to the initial
> correction.

Martin, the 10 ms behavior is pretty much a given, since the OS clock 
works at the same 10 ms resolution!

The realtime thread hack to interpolate between OS ticks does help, but 
NTPD still needs a lot of statistical data to be able to settle down at 
offset values well below the OS tick!

Terje

-- 
- <Terje.Mathisen at hda.hydro.com>
"almost all programming can be viewed as an exercise in caching"




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