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RE: [Xen-users] Another GPLPV pre-release 0.9.11-pre20

To: <Pekka.Panula@xxxxxxxx>
Subject: RE: [Xen-users] Another GPLPV pre-release 0.9.11-pre20
From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
Date: Wed, 5 Nov 2008 19:49:52 +1100
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Thread-topic: [Xen-users] Another GPLPV pre-release 0.9.11-pre20
> Great, no BSOD yet,

That's good.

> but still i cant use Checksum offloading or Large send
> Offload.

That's not so good...

> I still see atleast some incorrect tcp chksums if Checksum Offloading
> enabled.

Where are you seeing these? If you are seeing them at any point before
the packet has passed through a physical network card then they will
indeed have an incorrect checksum. The checksum calculation should be
deferred until the latest possible time.

> Large Send Offload is also makeing Bacula to have very slow to
> speeds, if Large Send offload is enabled Bacula transfer speed is
> something like 30kB/sec, if i disable Large Send Offload it will go to
> about 70-80Mbit/sec.

Do you have a Linux PV DomU with lso enabled on that you can test also?

Can you describe (again, if you have done so previously) precisely your
network layout? Eg what vif is bridged to what physical adapter, and
where abouts on the network you are sending packets to and from.

Also, what is the output of 'cat
/proc/sys/net/bridge/bridge-nf-call-iptables'. If it's not 0, then
please try 'echo 0 > /proc/sys/net/bridge/bridge-nf-call-iptables'. This
will stop bridge packets being touched by iptables, which may be the
cause of the problems you are seeing. If the Dom0 actually routes the
packets instead of bridging them (eg if the packet needs to go out a
Dom0 interface that is not on the same bridge) then iptables may become
involved, but by then hopefully it's okay.

Otherwise, based on your network layout I'll give you some places to
take some packet captures from and some other testing to do.


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