[time] Best attainable offset of ntpd?

John Pettitt jpp
Fri Jun 23 16:09:13 UTC 2006


Philip M. White wrote:
> All,
>
> What is the best offset that you have been able to attain with ntpd?
> With a Garmin 18 LVC + LinuxPPS + Linux 2.6.17 + ntpd 4.20, the best I
> can get is an offset of about 0.006 ms.  This offset is never steady --
> it drifts from positive to negative.  Right *now*, for example, it is
> -0.017 ms.  I use this machine for real work and play (X, multimedia,
> OpenOffice, etc.).
>
> My delay is consistently 0.000 ms, and jitter is 0.001-0.002 ms, so
> those are good.  Is my offset good for a stratum-1 machine?  Can
> anything be done to minimize and stabilize the offset?  Probably the key
> factor is my activity on this machine, but is there anything else?
>
>   
That is about as good as you will get without replacing the crystal in
your machine with an ovenized one that is not sensitive to temperature
swings.  With a standard crystal if you plot the frequency correction
NTP is applying you'll be able to see changes in machine load and room temp.

John


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