[ntp:questions] NTP vs chrony comparison (Was: oscillations in ntp clock synchronization)

Danny Mayer mayer at ntp.isc.org
Mon Jan 28 13:01:55 UTC 2008


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 eliminate--
> 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.

Danny



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