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Subject: Re: Timing issue with Dummynet on high kernel timer interrupt
To: Ian Lepore <ian@freebsd.org>, Luigi Rizzo <rizzo@iet.unipi.it>
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Cc: Rasool Al-Saadi <ralsaadi@swin.edu.au>,
 "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>,
 Alexander Motin <mav@FreeBSD.org>,
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From: Hans Petter Selasky <hps@selasky.org>
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Date: Fri, 6 Nov 2015 17:57:29 +0100
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On 11/06/15 17:51, Hans Petter Selasky wrote:
> On 11/06/15 17:43, Ian Lepore wrote:
>> On Fri, 2015-11-06 at 17:28 +0100, Hans Petter Selasky wrote:
>>> Hi,
>
>>
>> Do the test II results change with this setting?
>>
>>    sysctl kern.timecounter.alloweddeviation=0
>>
>
> Yes, it looks much better:
>
> debug.total: 10013 -> 0
> debug.total: 10013 -> 0
> debug.total: 10012 -> 0
> debug.total: 10012 -> 0
> debug.total: 10012 -> 0
> debug.total: 10013 -> 0
> debug.total: 10012 -> 1
> debug.total: 10013 -> 0
> debug.total: 10013 -> 0
> debug.total: 10013 -> 0
> debug.total: 10012 -> 0
> debug.total: 10013 -> 0
> debug.total: 10013 -> 0
>
> --HPS
>

Thought I still see some unexpected dips, as the test runs for a longer 
amount of time. Not sure what the cause might be.

> debug.total: 10013 -> 0
> debug.total: 10013 -> 0
> debug.total: 10013 -> 0
> debug.total: 9844 -> 0
> debug.total: 10013 -> 0
> debug.total: 10013 -> 0
> debug.total: 10012 -> 0

--HPS