[ntp:questions] NTP vs chrony comparison (Was: oscillations in ntp clock synchronization)
unruh at physics.ubc.ca
Mon Jan 28 15:36:51 UTC 2008
What was the problem?
On Mon, 28 Jan 2008, Danny Mayer wrote:
> Unruh wrote:
>> mayer at ntp.isc.org (Danny Mayer) writes:
>> > David L. Mills wrote:
>> > > Danny,
>> > >
>> > > It doesn't stop working; it just clamps whatever it gets to +-500 PPM
>> > > as appropriate. If the intrinsic error is greater than 500 PPM, the
>> > > loop will do what it can with the residual it can't correct showing as
>> > > a systematic time ofset.
>> > >
>> > > Dave
>> > >
>> > I didn't mean to suggest that ntpd stopped running. It was that the
>> > clock was drifting steadily off into the sunset. I realize that if the
>> > problem corrected itself ntpd would bring things back to normal.
>> But that suggests that the drift rate of your chip became bigger than
>> 500PPM, which is huge. Maybe something altered the tick size
>> inappropriately. ntp should have hauled the offset back to zero -- just
>> taking a longer time ( 100msec at 500PPM takes about 200 sec to
>> which is not that long.)
> No, it was something else entirely and not something that ntpd, chrony or any
> other application could do anything about. It's fixed now.
William G. Unruh | Canadian Institute for| Tel: +1(604)822-3273
Physics&Astronomy | Advanced Research | Fax: +1(604)822-5324
UBC, Vancouver,BC | Program in Cosmology | unruh at physics.ubc.ca
Canada V6T 1Z1 | and Gravity | www.theory.physics.ubc.ca/
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