[ntp:questions] Repost: Are there algorithm differences between 4.2.4 and 4.2.5?
mills at udel.edu
Fri Apr 10 20:15:58 UTC 2009
The core clock discipline (ntp_loopfilter.c) PLL, FLL and poll-adjust
routines have not changed between the release and development versions.
Details in the initial frequency computation, kernel interface,
leapsecond processing and configuration interface have been updated.
There were minor changes in the loop dynamics for very long poll
intervals (36 h) to improve stability. These changes have no effect for
poll intervals less than 4096 s. The loop dynamics should be unchanged
Some of the routines in the release version date from 2006 and and have
been significantly updated in the development version. Other routines in
the release version date from this year and are very likely incompatible
with the old routines in one way or another. I have no idea whether this
might or might not affect the behavior.
David J Taylor wrote:
>David J Taylor wrote:
>>Are there any algorithm of other differences which might cause
>>noticeable performance differences between 4.2.4 and 4.2.5? For
>>- 4.2.5 being more reluctant to increasing the polling interval from
>>64s (with a mixture of local stratum-1 and Internet pool servers)?
>>- 4.2.5 showing an increased variability of offset when viewed on a
>>timescale of minutes?
>>Of course, these may just be different manifestations of the same
>It would be good to hear from the algorithm experts about this topic.
>There are some comparative results here:
>questions mailing list
>questions at lists.ntp.org
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