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RE: [Xen-users] Slow Network Performance on GPLPV 9.12-pre13

To: "Mark Pace" <pace@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-users] Slow Network Performance on GPLPV 9.12-pre13
From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
Date: Fri, 17 Apr 2009 15:45:12 +1000
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Thread-topic: [Xen-users] Slow Network Performance on GPLPV 9.12-pre13
> > How are you testing performance? And are you measuring from
> > or DomU->external host?
> >
> >
> Copying to and from a SMB share, I've tried the following at this
> DomU->DomU on same host, speed is good both copying to and from the
> DomU->External Hosts, copying from the share to the DomU is good,
> copying to the share is really slow.
> So I tried FTP and SCP instead of SMB traffic:
> DomU->DomU on same host, speed is good both directions
> DomU->External Host, speed is good both directions
> Something strange is afoot...
> > If the latter, then your network adapter may not support TCP task
> > offload (checksum / large send), although if that was the case I
> > expect that your performance would be kbits not mbits...
> >
> >
> Definitely have TCP offload on these machines.  Built in Intel Gigabit
> connectors on Supermicro motherboard.
> The condition is the same across the three different 2003 DomUs I have
> on this host.  I do have another host around that I can move one of
> these DomUs onto to see what happens there.

Just turn off checksum offload and large send offload in the DomU
(advanced properties of network adapter). See if that makes a


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