[Qemu-devel] Re: question on virtio

[Rusty Russell]

On Wed, 5 May 2010 08:39:47 pm 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.

I agree.  From my TODO:
        what if we actually expose in ->add_buf?

I don't *think* anyone adds buffers without being ready for them to be used,
so changing this should be safe.

Want to give it a try and report back?

Thanks!
Rusty.