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Re: [Xen-devel] Strange network behaviour


  • To: Marco Tizzoni <marco.tizzoni@xxxxxxxxx>
  • From: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
  • Date: Tue, 28 Jul 2009 15:15:28 +0100
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Tue, 28 Jul 2009 07:15:51 -0700
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That's a difference of only 0.5%.  It is interesting that it's
bi-modal, but I don't think it's very significant.  If you're really
keen to just understand where that comes from, you can try taking a
trace and analyzing the results.

 -George

On Tue, Jul 28, 2009 at 3:09 PM, Marco Tizzoni<marco.tizzoni@xxxxxxxxx> wrote:
> On Tue, Jul 28, 2009 at 3:03 PM, George
> Dunlap<George.Dunlap@xxxxxxxxxxxxx> wrote:
>> What's the granularity of your measurement?
>
> I use tcpdump/tshark to dump e decode incoming packets and I think it
> uses the timestamp from the nic.
> The two gaps are 0.011781 and 0.011731 and they remain constant over
> the time. This is a snap:
>
> # Order  AbsoluteTime  DeltaTime
> 1 0.000000 0.000000
> 2 0.009734 0.009734
> 3 0.021515 0.011781
> 4 0.033245 0.011730
> 5 0.045027 0.011782
> 6 0.056757 0.011730
> 7 0.068538 0.011781
> 8 0.080269 0.011731
> 9 0.092050 0.011781
> 10 0.103831 0.011781
> 11 0.115562 0.011731
> 12 0.127342 0.011780
> 13 0.139073 0.011731
>
>
> Attached a decoded dump of 10 seconds with arrival order, absolute
> time, relative time.
> Also you can find a graph where this issue is clear.
>
> Thanks,
> Marco
>
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>

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