Subject: Re: [PATCHv2 06/14] virtio: add api for delayed callbacks

From: Rusty Russell <rusty-8n+1lVoiYb80n/[email-masked]>
Date: Sat, 21 May 2011 12:03:35 +0930

On Fri, 20 May 2011 02:11:14 +0300, "Michael S. Tsirkin" <[email-masked]> wrote:
> Add an API that tells the other side that callbacks
> should be delayed until a lot of work has been done.
> Implement using the new event_idx feature.
> 
> Note: it might seem advantageous to let the drivers
> ask for a callback after a specific capacity has
> been reached. However, as a single head can
> free many entries in the descriptor table,
> we don't really have a clue about capacity
> until get_buf is called. The API is the simplest
> to implement at the moment, we'll see what kind of
> hints drivers can pass when there's more than one
> user of the feature.
> 
> Signed-off-by: Michael S. Tsirkin <[email-masked]>

Yes, I've applied this (and the next one which uses it in virtio_net),
despite my reservations about the API.  But that is fixable...

Thanks,
Rusty.