Re: [PATCH 09/18] virtio: use avail_event index

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

On Wed, May 18, 2011 at 09:49:42AM +0930, Rusty Russell wrote:
> On Tue, 17 May 2011 09:10:31 +0300, "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > Well one can imagine a driver doing:
> > 
> > 	while (virtqueue_get_buf()) {
> > 		virtqueue_add_buf()
> > 	}
> > 	virtqueue_kick()
> > 
> > which looks sensible (batch kicks) but might
> > process any number of bufs between kicks.
> 
> No, we currently only expose the buffers in the kick, so it can only
> fill the ring doing that.
> 
> We could change that (and maybe that's worth looking at)...

That's actually what one of the early patches in the series did.
I guess I can try and reorder the patches, I do believe
it makes sense to publish immediately as this way
host can work in parallel with the guest.

> > If we look at drivers closely enough, I think none
> > of them do the equivalent of the above, but not 100% sure.
> 
> I'm pretty sure we don't have this kind of 'echo' driver yet.  Drivers
> tend to take OS requests and queue them.  The only one which does
> anything even partially sophisticated is the net driver...
> 
> Thanks,
> Rusty.

I guess I'll just need to do the legwork and check then.

-- 
MST