[Spice-devel] [PATCH 28/35] vdi port: redesign.

[Gerd Hoffmann]

   Hi,

> I'm not sure how that should be done. My main dislike of the current interface
> is that it forces either a copy from the driver to an intermediate, like
> the code I had checked in, or it forces spice-server to consume everything it gets.

No, it isn't all or nothing.  You can delay the intermediate copy until 
the wakeup() call returns, then only copy in case the server didn't 
consume all data.

I'm not sure this is worth the trouble though.  With bulky data we 
likely have to throttle (and thus copy) frequently anyway.  With 
low-bandwith data the extra copy doesn't hurt much.

> The other is to have a havedata callback instead of read, called from driver,
> allow the havedata to return a boolean telling it if to throttle or not, and
> have another "unthrottle" function called from spice.
>   - change of API
>   + no additional copy of data

Yes, you need an additional interface for throttle/unthrottle then. 
Works too.  I don't mind much which way we pick.

cheers,
   Gerd