netdev - Re: [RFC PATCH] Regression in linux 2.6.32 virtio

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Message-ID: <20091216025331.GA13935@gondor.apana.org.au>
Date:	Wed, 16 Dec 2009 10:53:31 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	Sridhar Samudrala <sri@...ibm.com>, mst@...hat.com,
	netdev@...r.kernel.org
Subject: Re: [RFC PATCH] Regression in linux 2.6.32 virtio_net seen with
	vhost-net

On Wed, Dec 16, 2009 at 01:11:40PM +1030, Rusty Russell wrote:
> 
>    Thanks for the hint.  They seem to use NAPI for xmit cleanup, so that's
> what we should do?  I'll try, but such a rewrite doesn't belong in 2.6.32.

Well it depends.  Real drivers can't touch the hardware so they're
stuck with whatever the hardware does.  For virtio we do have the
flexibility of modifying the backend.

Having said that, for existing backends that will signal when there
is just a single free entry on the queue something like NAPI could
reduce the overhead associated with the IRQs.

Cheers,
-- 
Visit Openswan at http://www.openswan.org/
Email: Herbert Xu ~{PmV>HI~} <herbert@...dor.apana.org.au>
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