Re: vhost-net patches

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Oct 23, 2009 at 09:23:40AM -0700, Shirley Ma wrote:
> Hello Michael,
> 
> Some initial vhost test netperf results on my T61 laptop from the
> working tap device are here, latency has been significant decreased, but
> throughput from guest to host has huge regression.

Could you please try adding ,sndbuf=0 to tap options, and re-testing?
This would make the -net option look like something like this:
-net tap,vlan=1,ifname=msttap0,script=/home/mst/ifup,downscript=no,sndbuf=0

> I also hit guest skb_xmit panic.

I have not seen panics in a while.
Could you provide more information please?
Is the panic reproducible?
Do you see one of these messages:
                 id %u out of range
                 id %u is not a head!


> 
> netperf TCP_STREAM, default setup, 60 secs run
> 
> guest->host drops from 3XXXMb/s to 1XXXMb/s (regression)
> host->guest increases from 3XXXMb/s to 4XXXXMb/s 
> 
> TCP_RR, 60 secs run (very impressive)
> 
> guest->host trans/s increases from 2XXX/s to 13XXX/s
> host->guest trans/s increases from 2XXX/s to 13XXX/s
> 
> Thanks
> Shirley
>