[PATCH 0/3] qemu-kvm: vhost net support

[Rusty Russell]

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.