[ntp:questions] Bug 2314, Clock jitter reads zero in the loopstats file

David J Taylor david-taylor at blueyonder.co.uk
Thu Jan 10 07:02:54 UTC 2013


I checked my home FreeBSD 8.2 NTP server for the clk_jitter reads zero bug, 
and yes, I see it too when using PPS kernel discipline.

server 127.127.22.1 flag3 1

http://www.eecis.udel.edu/~mills/ntp/html/drivers/driver22.html

So, I need to understand what "Controls the kernel PPS discipline" means and 
what the differences in code are between disabled, (default), and enabled 
are.  I also need to understand the importance of the clock jitter 
statistic; I notice that system jitter is still reported with kernel PPS 
discipline enabled.  If system jitter is less --yet to be determined--with 
kernel PPS discipline enabled, wouldn't that imply that kernel PPS would be 
prefered, regardless of reported clock jitter?  Again, I have been mostly 
concerned with the clock offset and the stability of the frequency.  I need 
to understand the importance and differences in both clock jitter and system 
jitter?

Regards,
Ed
==========================================

More later, but could you please add your comments to bug 2314.

https://support.ntp.org/bugs/show_bug.cgi?id=2314

Thanks,
David
-- 
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk 



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