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RE: [Xen-users] GPLPV Driver and SMP

To: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>, "Klaus Steinberger" <klaus.steinberger@xxxxxxxxxxxxxxxxxxxxxx>, <xen-users@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-users] GPLPV Driver and SMP
From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
Date: Fri, 22 Aug 2008 11:15:53 +1000
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Thread-topic: [Xen-users] GPLPV Driver and SMP
> >
> > It looks like it waits too long for packets to be sent.
> >
> 
> In testing from Dom0 to DomU with vcpus=4 I get marginally worse
> performance than with vcpus=1. Can you tell me as much as you can
about
> the above setup so I can attempt to reproduce it?
> 

Actually... I wish to change my statement :)

When I use iperf with -P4, I get the following for the 4 connections:

[ ID] Interval       Transfer     Bandwidth
[1800]  0.0-10.0 sec  1.19 GBytes  1.02 Gbits/sec
[1844]  0.0-10.0 sec  1.13 GBytes   967 Mbits/sec
[1748]  0.0-14.0 sec  13.5 MBytes  8.05 Mbits/sec
[1836]  0.0-15.9 sec   391 MBytes   207 Mbits/sec
[SUM]  0.0-15.9 sec  2.71 GBytes  1.47 Gbits/sec

The test is only supposed to run for 10 seconds, so the fact that it
takes an additional 4-6 seconds for two of the connections to finish up
means that maybe things aren't as they should be.

Sometimes iperf runs all the connections at full speed (giving me around
2.4GBit/second) but sometimes some of them stall and I get much worse
performance.

Something to investigate I suppose.

James


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