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From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: Network performance with small packets
Date: Wed, 2 Feb 2011 17:48:41 +0200
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Cc: Sridhar Samudrala <sri@us.ibm.com>,
	Steve Dobbelstein <steved@us.ibm.com>,
	David Miller <davem@davemloft.net>, kvm@vger.kernel.org,
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To: Shirley Ma <mashirle@us.ibm.com>
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On Wed, Feb 02, 2011 at 07:42:51AM -0800, Shirley Ma wrote:
> On Wed, 2011-02-02 at 12:49 +0200, Michael S. Tsirkin wrote:
> > On Tue, Feb 01, 2011 at 11:33:49PM -0800, Shirley Ma wrote:
> > > On Tue, 2011-02-01 at 23:14 -0800, Shirley Ma wrote:
> > > > w/i guest change, I played around the parameters,for example: I
> > could
> > > > get 3.7Gb/s with 42% CPU BW increasing from 2.5Gb/s for 1K message
> > > > size,
> > > > w/i dropping packet, I was able to get up to 6.2Gb/s with similar
> > CPU
> > > > usage. 
> > > 
> > > I meant w/o guest change, only vhost changes. Sorry about that.
> > > 
> > > Shirley
> > 
> > Ah, excellent. What were the parameters? 
> 
> I used half of the ring size 129 for packet counters, but the
> performance is still not as good as dropping packets on guest, 3.7 Gb/s
> vs. 6.2Gb/s.
> 
> Shirley

And this is with sndbuf=0 in host, yes?
And do you see a lot of tx interrupts?
How packets per interrupt?

-- 
MST