Re: PCI pass-through of NIC to PV DomU... worth it?

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Thu, Feb 23, 2012 at 10:51:07PM -0500, David Howland wrote:
> Either my Google-fu is weak or nobody has actually asked this in the
> open before...
> 
> Is it worth it to try and use PCI pass-through to give a NIC to a PV
> DomU?  I'm setting up a DomU firewall/router.  I want the latency to
> be as low as possible.
> 
> I need to know which is faster: the PV network interface or passing
> the NIC?  I don't have VT-d support, but the server is a dual
> quad-core Xeon setup, so I shouldn't be short on compute cycles.  My
> gut is telling me that there wouldn't be any tangible difference,
> but I want to hear what the experts think.

Running the NIC driver in the domU may help with latency, as it'll
avoid context switches between dom0 and domU. Also, you'll be able
to use checksum offloads.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--