[ntp:questions] Re: Frequent time reset messages

ega egauselmann at beit.de
Mon Dec 5 11:53:30 UTC 2005


Bob Robison schrieb:
> I've tried setting the Hz down to 100, but it didn't help -- and seems
> to have caused other timing problems, but I may revisit that at some
> point.  I do believe the problem is lost interrupts, but I don't know
> how to be sure without hacking the firewire driver and trying to
> determine how long it is in there.  And if I found out, I'm not sure
> what I could do.
>
> At the moment I'm trying to get it to simply step/adjust more often.
> I've adjusted minpoll/maxpoll to 4 (to get 16 secs) and I understand
> that the default step threshold is 128ms.  However I still see offsets
> that are larger than that, and the 'steps' only occur every 20 or 30
> minutes.  How can I have it happen more often?

If the problem is not due to lost interrupts you might want to try
this: stick the ntpd process with a specific CPU. Execute
  taskset -p 1 `pidof /usr/sbin/ntpd`
The program 'taskset' is out of 'schedutils' from here:
  http://rlove.org/schedutils/schedutils-1.5.0.tar.gz
The package might already come with your distro. If this settles
down the offset watch out for a recent kernel with the SMP+TSC
problem solved.

--ega




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