[ntp:questions] ntpd with Intel SpeedStep and AMD PowerNow, any updates?

Ryan Malayter malayter at gmail.com
Fri Mar 23 13:09:50 UTC 2007

On Mar 21, 2:01 am, Ryan Moore <rmo... at rmoore.dyndns.org> wrote:
> Hmm, I'm not seeing any issues with AMD PowerNow and ntpd on my Linux box.
> I use that feature and my ntpd works just fine.

I did some testing with ntpd 4.2.0a and Ubuntu 6.10 (kernel
on my Pentium-M laptop (with 'ondemand' processor scaling enabled),
and everything seemed to work well, even when I preiodically stopped
and started the cpuburn utility to force the processor to scale
speeds. ntpd did not panic and exit, and jitter was fairly low.

So it would appear we have at least two data points that indicate
frequency scaling is no longer an issue for ntpd, at least with more
recent Linux kernels.

I suspect, as Harlan suggested, that it was an OS issue with older
kernels using the time stamp counter instead of the PM timer in the
kernel time APIs.

Do you think I should update the wiki with this information, or should
I wait for further tests on other hardware platforms and Linux distros
(we're planning on RHEL for the new servers)?


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