[Spice-devel] RFC: Integrating Virgil and Spice

[Marc-André Lureau]

----- Original Message -----
> Hi,
> 
> On 10/10/2013 01:25 PM, Gerd Hoffmann wrote:
> >    Hi,
> >
> > Nice summary.
> >
> >> 3) Virgil will render using the host gpu, using EGL to talk to
> >> a drm render node. For non local displays the rendered contents
> >> will be read back from the gpu and then passed as a pixmap to the
> >> ui to transport over the network
> >
> > Interesting in this context:  What is the status of 3d support for
> > qxl/spice?
> 
> Non existent AFAIK
> 
> > Is it be possible to transform virgil 3d ops into spice 3d
> > ops, so you could offload the rendering to spice-client?  Does it make
> > sense to try?  Or would the transfer of the data needed to render more
> > expensive than transferring the rendered screen?
> 
> AFAIK, people more knowledgable people then me on 3d (ie Keith Packard)
> all seem to agree on that transfering the commands to render would be
> more expensive. IOW adding 3d support to Spice would be not really useful.

afaik, opengl has been designed originally with remote rendering in mind.

I am no opengl expert, but it probably very much depends on the kind of application (Alon reported us about Android apps remoting being fine). Wouldn't glx gears be fine too? ;) I think the upcost is pretty big in general, because of upload of textures and data arrays which are not very well compressed in raw protocol. Probably a remote protocol, like spice, could help compress those (and cache on disk!). Then result can be read back in some applications, but that is not always the case (even rendering to texture and composition could be done remotely). Usage of readback is discouraged in general. Imho, it could be worth some experiments. But current local only approach is necessary anyway, and the server rendering approach could be complementary too.