Re: [Flightgear-devel] Shader performance and multiple GPU?

[Tim M. <tim...@gm...>]

This mirrors comments to the OSG mailing list, where people have reported
performance issues with multiple GPUs and screens. There hasn't been much of
a resolution there; some people have the problem, others don't. I've put
together a multi-GPU machine to explore these issues; now I just need to buy
another screen :)

What threading  mode are using? Could you post a screenshot of the OSG
statistics (cycle debug statistics twice) and your X configuration file?

Tim

On Mon, Nov 1, 2010 at 9:06 AM, Torsten Dreyer <To...@t3...> wrote:

> Hi,
>
> as pointed out in other threads, I am currently assembling a machine with
> five
> nVidia cards. The machine and the cards are fast enough to render a steady
> 60fps, synced to vblank.
> But this is only with shaders disabled. The moment, I enable shaders and
> 3d-
> clouds, the frame rate drops to 20fps and sometimes even less. This does
> not
> happen when I limit the display to just one single GPU. One GPU with dual
> screen ("TwinView") runs at framerates beyond limits even with all shaders
> on
> and quality level to highest. The moment I add a second card to the setup,
> it
> slows down significantly.
> I know that shaders are little program fragments running on the GPU itself.
> Now, what happens, if a shader effect spawns multiple GPU's, e.g. a cloud
> which is visible across the entire window?
>
> Cheers, Torsten
>
>
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