[ntp:questions] Clock skew changes drastically between reboots

Hans Jørgen Jakobsen hjj at wheel.dk
Mon Apr 2 13:38:03 UTC 2007


On Mon, 2 Apr 2007 06:36:27 GMT, Dmitry Ivanov wrote:
> On 1 Apr 2007, at 21:44, Spoon wrote:
>
>> Hello everyone,
>>
>> I've noticed something I find very strange on the systems I have to  
>> work
>> with. Every time I reboot the computer, the clock skew of the local
>> clock changes, sometimes by what seems to be a huge amount.
>>
>> For example, I boot the computer, let ntpd run for 12 hours, and the
>> value recorded in the drift file is 35 ppm. I reboot the computer, let
>> ntpd run for 12 hours, and I get 5 ppm...
>
> Hi!
>
> I see the same behaviour on many systems. Looks like common problem.

Could it be that some systems at reboot try to calibrate the clock
(whatever that might be) relative to the TOD chip?
On some systems the TOD chip has the lowest frequency offset
and this would on systems not runing NTP lead to a system drifting less.
But its poison for the value in the driftfile.
/hjj




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