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

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Message-ID: <20091216015829.GB13068@gondor.apana.org.au>
Date:	Wed, 16 Dec 2009 09:58:29 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	"Michael S. Tsirkin" <mst@...hat.com>
Cc:	Sridhar Samudrala <sri@...ibm.com>, rusty@...tcorp.com.au,
	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 01:32:27AM +0200, Michael S. Tsirkin wrote:
> 
> Right. Hmm. So for this to work we'll need to
> 1. Free skb upon interrupt instead of
>    waiting for the next xmit call

No the next xmit call can free the skbs.

> 2. Add API to query free ring capacity

This is all you need.

> We could also extend host to delay interrupt
> until there is sufficient TX capacity
> but of course we also need to support
> old hosts as well.

Yes that what real hardware does too.  They are able to delay
the interrupt until the number of free entries exceeds a minimum
threshold.

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