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- To: chrony-dev@xxxxxxxxxxxxxxxxxxxx
- Subject: Re: [chrony-dev] SW/HW timestamping on Linux
- From: Denny Page <dennypage@xxxxxx>
- Date: Fri, 25 Nov 2016 17:11:08 -0800
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I believe the stddev issue with multiple interfaces may have been leftover sampling from prior runs. I cleared all the point data, and things looked better. Sorry about that.
The priority issue remains, but I don’t think it’s a big deal per se. When running with scheduling priority (-P 9), I see about 30% of ‘D H’ for the fast units. Running without priority I see virtually none (all ‘H H’). I don’t believe that this is much of an issue, because scheduling priority is really only needed when daemon timestamps are in use. With hardware or driver timestamps, it isn't necessary.
Denny
> On Nov 24, 2016, at 05:11, Miroslav Lichvar <mlichvar@xxxxxxxxxx> wrote:
>
> On Wed, Nov 23, 2016 at 03:24:56PM -0800, Denny Page wrote:
>> I am now seeing better standard deviations with hardware timestamping than software timestamping. Thank you.
>>
>> Couple of caveats:
>> - I need to disable priority scheduling (-P). With priority scheduling, software stamps still have lower stddev.
>> - I can only use a single ethernet interface. With multiple interfaces, software stamps still have lower stddev.
>
> That's interesting. Were you testing this with the patch that ignores
> non-HW measurements and did any of these two things change probability
> of getting a 'D H' measurement?
>
> FWIW, I tried running chronyd with -P 50 for a bit and I didn't notice
> any changes.
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