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

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" [off-list ref] wrote:

quoted

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.

quoted

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