The right tool to use: XGetImage or Compositing or something else entirely

[Alex Deucher]

On Wed, Feb 23, 2011 at 2:24 PM, Philip Lawatsch <philip at lawatsch.at> wrote:
> Hi,
>
> I'm trying to get some direction / advice on how to proceed. I'm not
> an experienced X developer (at least not with the raw x11 libs), so
> I'm thankful for any advice.
>
> What I'm trying to do is write some support to use an nvidia "optimus"
> system under linux (basically one has two graphics cards, but only one
> of the is connected to physical displays).
> I've already written a prototype that can do (almost) everything I
> want but am looking at ways to speed things up.
>
> The way  I've done it is to start two x servers at the same time, one
> using the intel driver, and one using the binary nvidia driver. Then
> my prototype / hack connects to both x servers, does XGetImage(nvidia,
> root_window) and XPutImage(intel, some_fullscreen_window). Then I
> start some normal desktop environment on the nvidia server and 'work'
> there, whilst getting my output via the display connected to the intel
> one.
>
> This however is way too inefficient on my laptop (getting around 40fps
> with 100% cpu usage).
>
> So, any suggestions / advice / best practices (other than not buying
> hardware like that) for how I should try to speed that up?

http://airlied.livejournal.com/71734.html

Alex