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

[Stefan Hajnoczi]

On Fri, Nov 2, 2012 at 3:48 PM, Michael S. Tsirkin <address@hidden> wrote:
> On Fri, Nov 02, 2012 at 11:18:18AM +0100, Stefan Hajnoczi wrote:
>> On Thu, Nov 1, 2012 at 5:07 PM, Michael S. Tsirkin <address@hidden> 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>
>>
>> Nice, much simpler than the ideas I had.
>>
>> Reviewed-by: Stefan Hajnoczi <address@hidden>
>
> Anthony could you apply this out of band please so this stops
> biting people?

Especially for the 1.3 release so that we don't have a virtio
performance regression.

Stefan