[ntp:questions] PPS jitter in Linux

Mike S mikes at flatsurface.com
Tue Apr 3 01:25:38 UTC 2012

On 4/2/2012 9:13 PM, Chris Albertson wrote:
> On Mon, Apr 2, 2012 at 4:28 PM, Mike S<mikes at flatsurface.com>  wrote:
I've played around with different cpufreq setting, thinking it might be
>> related to the processor speed during an IRQ, but that seems to have minimal
>> impact (performance vs. conservative vs. ondemand).
> I think your CPU goes into some power saving mode when there is no
> load and takes some number of micro seconds to wake up after an
> interrupt.   Keeping a load on it prevents the sleep or power save
> mode and hence the need to "wake up."

Then explain why setting the cpufreq governor to "performance" (which 
locks it to the highest frequency ( 
http://www.mjmwired.net/kernel/Documentation/cpu-freq/governors.txt ) 
has no significant effect.

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