netdev - Re: Network performance with small packets

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Message-ID: <20110202062950.GD3818@redhat.com>
Date:	Wed, 2 Feb 2011 08:29:50 +0200
From:	"Michael S. Tsirkin" <mst@...hat.com>
To:	Shirley Ma <mashirle@...ibm.com>
Cc:	Sridhar Samudrala <sri@...ibm.com>,
	Steve Dobbelstein <steved@...ibm.com>,
	David Miller <davem@...emloft.net>, kvm@...r.kernel.org,
	mashirle@...ux.vnet.ibm.com, netdev@...r.kernel.org
Subject: Re: Network performance with small packets

On Tue, Feb 01, 2011 at 10:19:09PM -0800, Shirley Ma wrote:
> On Tue, 2011-02-01 at 22:05 -0800, Shirley Ma wrote:
> > 
> > The way I am changing is only when netif queue has stopped, then we
> > start to count num_free descriptors to send the signal to wake netif
> > queue. 
> 
> I forgot to mention, the code change I am making is in guest kernel, in
> xmit call back only wake up the queue when it's stopped && num_free >=
> 1/2 *vq->num, I add a new API in virtio_ring.

Interesting. Yes, I agree an API extension would be helpful. However,
wouldn't just the signaling reduction be enough, without guest changes?

> However vhost signaling reduction is needed as well. The patch I
> submitted a while ago showed both CPUs and BW improvement.
> 
> Thanks
> Shirley

Which patch was that?

-- 
MST
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