[ntp:questions] NTPD can take 10 hours to achieve stability

David Lord snews at lordynet.org
Tue Apr 19 10:02:08 UTC 2011

David J Taylor wrote:
> "unruh" <unruh at wormhole.physics.ubc.ca> wrote in message 
> news:slrniqpa40.ppu.unruh at wormhole.physics.ubc.ca...
> []
>> Well, I think someone other than the current maintainers will have to
>> port it to windows. Since windows timekeeping is not the worlds best
>> anyway, it is probably true that the extra accuracy of chrony is
>> unnecessary. It does have a command line option "like ntpq -p"
>> provided by chronyc (depending on what you mean by "like").
>> What MRTG is I do not know.
>> If you are happy with ntpd, by allmeans stay with it.
> A pity that chrony will not be offered for Windows, at least for tests 
> to see whether it lives up to its claims.  There are times when a more 
> rapid convergence would be welcome, such as the reboot of PC Molde 
> around 13:30 yesterday:
>  http://www.satsignal.eu/mrtg/molde_ntp-b.html
> MRTG is a standard logging tool for network I/O which uses SNMP to 
> produce the graphs I have quoted here many times for network throughput 
> and timekeeping:
>  http://www.satsignal.eu/mrtg/performance_network.php
>  http://www.satsignal.eu/mrtg/performance_ntp.php
> I've written how to extend MRTG to monitor NTP timekeeping, and various 
> other parameters such as disk space and temperature here:
>  http://www.satsignal.eu/ntp/NTPandMRTG.html
>  http://www.satsignal.eu/mrtg/performance_howto.php
>  From chronyc I would need to be able to use a simple Perl script to 
> extract the numbers to be plotted - such as the Offset in the graphs 
> above.  An easy job if the format is standardised and machine readable.

I based my script on yours for ntp but changed from using a
linear axis to log. I first used chrony on NetBSD when on
dialup with demon and later for a while when on broadband.
When I first compared chrony with ntpd there was no contest
but more recent experiments with chrony had periods of
severe instability much worse than ntpd.

P4X2666 with chrony

Current stats all with ntpd.


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