[ntp:questions] strange sign change in clock drift with linux

mike michael.no.spam.cook at wanadoo.fr
Sun Apr 16 21:29:42 UTC 2006

Yesterdaw I upgraded my linux kernel from to in order 
to take advantage of the PPSKit. I have changed neither the NTP version 
nor the config. After rebooting and checking that all
was working, I noticed that the calculated local drift had switched
from its former stable -32 ppm to a positive value of +27 ppm. Over the 
past 4 years it has been recorded as being the negative figure over
numerous upgrades of both kernel and NTP code.
The positive value stayed stable over 24hrs, so I then rebooted the kernel to see if it reverted, and sure enough it drifted back to 
-ve , getting to near its normal value after about 3hrs,
[mike at quark KERNEL]$ cat  /var/tmp/ntpdrift-
[mike at quark KERNEL]$ cat  /etc/ntp/drift

NTP seems to be adjusting to the percieved change as it doesn't appear 
to have had any effect in relation to the offset I am seeing with 
external servers such as NIST (not in my server config).

[mike at quark KERNEL]$ ntpdate -d time-nw.nist.gov
delay 0.22145, dispersion 0.00163
offset -0.007404

Has anyone else seen such changes?

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