From mboxrd@z Thu Jan  1 00:00:00 1970
From: Rusty Russell <rusty@rustcorp.com.au>
Subject: Re: [PATCH 0/3] qemu-kvm: vhost net support
Date: Thu, 20 Aug 2009 16:49:47 +0930
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References: <20090810192304.GA16781@redhat.com> <4A808840.70704@codemonkey.ws> <20090812173548.GA29981@redhat.com>
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Cc: "Michael S. Tsirkin" <mst@redhat.com>,
	Anthony Liguori <anthony@codemonkey.ws>, avi@redhat.com,
	kvm@vger.kernel.org
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On Thu, 13 Aug 2009 03:05:48 am Michael S. Tsirkin wrote:
> On Mon, Aug 10, 2009 at 03:51:12PM -0500, Anthony Liguori wrote:
> > Any rough idea on performance?  Better or worse than userspace?
> 
> Well, I definitely see some gain in latency.
...
> Part of it might be that tx mitigation does not come into play with vhost. I
> need to disable it in qemu and see.

A simple test I've found reasonably indicative when looking at base performance (before stuff like TSO get involved) is to do pings.  Throughput with "ping -s 1024 -l 120 -c 1000000 -f -q" and latency with "ping -c 1000000 -f -q".

(You may need to cut -l down if your ring is too small).

Cheers,
Rusty.