Re: [Qemu-devel] [PATCH] virtio: limit avail bytes lookahead

[Michael S. Tsirkin]

On Thu, Nov 29, 2012 at 06:34:46PM +0530, Amit Shah wrote:
> On (Wed) 28 Nov 2012 [23:53:08], Michael S. Tsirkin wrote:
> > On Tue, Nov 27, 2012 at 06:25:04PM +0200, Michael S. Tsirkin wrote:
> > > On Thu, Nov 01, 2012 at 06:07:21PM +0200, Michael S. Tsirkin wrote:
> > > > Commit 0d8d7690850eb0cf2b2b60933cf47669a6b6f18f introduced
> > > > a regression in virtio-net performance because it looks
> > > > into the ring aggressively while we really only care
> > > > about a single packet worth of buffers.
> > > > To fix, add parameters limiting lookahead, and
> > > > use in virtqueue_avail_bytes.
> > > > 
> > > > Signed-off-by: Michael S. Tsirkin <address@hidden>
> > > > Reported-by: Edivaldo de Araujo Pereira <address@hidden>
> > > 
> > > Ping.
> > > Anthony - going to apply this?
> > 
> > virtio rng was added since so naturally build broke.
> > Here's a patch on top to fix it up. I never used virtio rng before so
> > could not test at this hour, but it does fix the build.
> > 
> > I'll take a look at how to test it tomorrow but any
> > info would be appreciated.
> > Amit could you pls review?
> 
> Looks fine, I assume you will send a v2 of the patch to Anthony?
> 
>               Amit


Anthony volunteered to test this so there will only be v2 if he sees
problems.