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RE: [Xen-users] Bad TCP accept performance

To: Russ Purinton <rpurinton@xxxxxxxxxxxxxxxxxxxxxxx>, Pasi Kärkkäinen <pasik@xxxxxx>
Subject: RE: [Xen-users] Bad TCP accept performance
From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
Date: Thu, 26 May 2011 10:55:25 +0800
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Thread-topic: [Xen-users] Bad TCP accept performance
> From: Russ Purinton
> Sent: Wednesday, May 25, 2011 11:49 PM
> I thought that even traffic still went thru the NIC to loop.  I 
> can't
> seem to find anything on the net supporting this one way or the other, though
> I've seen multiple posts about pinging to test and verify the NIC 
> card
> and drivers working properly.  Not sure what this means.
> Also, if it doesn't pass to the NIC, the NIC then the question arises how the 
> IP
> and TCP checksums are being applied if offloading is enabled and it doesn't 
> pass
> thru the NIC.
> I had thought that on a physical host, the loopback ping would hit the network
> card.  I'm guessing with a virtual host, the loopback ping would only hit the

loopback driver simply queues the tx packet back to rx queue, and there's 
to do with underlying NIC. 


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