From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [RFC PATCH 1/1] vhost: TX used buffer guest signal accumulation
Date: Fri, 29 Oct 2010 10:12:56 +0200
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Cc: David Miller <davem@davemloft.net>, netdev@vger.kernel.org,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
To: Shirley Ma <mashirle@us.ibm.com>
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On Thu, Oct 28, 2010 at 01:13:55PM -0700, Shirley Ma wrote:
> On Thu, 2010-10-28 at 12:32 -0700, Shirley Ma wrote:
> > Also I found a big TX regression for old guest and new guest. For old
> > guest, I am able to get almost 11Gb/s for 2K message size, but for the
> > new guest kernel, I can only get 3.5 Gb/s with the patch and same
> > host.
> > I will dig it why. 
> 
> The regression is from guest kernel, not from this patch. Tested 2.6.31
> kernel, it's performance is less than 2Gb/s for 2K message size already.
> I will resubmit the patch for review. 
> 
> I will start to test from 2.6.30 kernel to figure it when TX regression
> induced in virtio_net. Any suggestion which guest kernel I should test
> to figure out this regression?
> 
> Thanks
> Shirley

git bisect 2.6.31 2.6.30
and go from here.