[Qemu-devel] Re: question on virtio

[Anthony Liguori]

On 05/05/2010 06:09 AM, Michael S. Tsirkin wrote:
> Hi!
> I see this in virtio_ring.c:
>
>          /* Put entry in available array (but don't update avail->idx *
>            until they do sync). */
>
> Why is it done this way?
> It seems that updating the index straight away would be simpler, while
> this might allow the host to specilatively look up the buffer and handle
> it, without waiting for the kick.
>    

It should be okay as long as you don't update idx for partial vectors.

Regards,

Anthony Liguori