[ntp:questions] Support for "tickless" systems

Miroslav Lichvar mlichvar at redhat.com
Wed Nov 19 11:56:11 UTC 2014


On Wed, Nov 19, 2014 at 10:09:42AM +0000, David Taylor wrote:
> In bug 2314, I reported that the jitter was always reported as 0 soon after
> NTP had started, and this was traced to the Linux in use on the Raspberry Pi
> being tickless.  Recompiling the kernel without the tickless option was a
> work-round, but is it possible to get jitter values with a tickless system?

There was a problem with clock stability in the tickless mode on idle
systems, which should be fixed or at least significantly improved in
3.17. I'm not sure how it could cause the jitter to be reported as
zero though.

Can you try 3.17 or later and see if it's fixed? Also, it would be
interesting to know if adding nohz=off to the kernel command line
instead of recompiling works as a workaround too.

-- 
Miroslav Lichvar


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