[osg-users] Rendering on two GPUs under linux

Nico Kruithof nicokruithof at gmail.com
Fri Nov 20 13:34:37 PST 2009


Hi,

We did some tests with SLI as well, GeForce 285. We had a single screen and
a way to expensive shader on a single quad. Just to be sure the CPU wasn't
the bottleneck. Worked like a charm. Frame rate doubled when we enabled SLI
under windows. We had to set the settings to alternate frame as the
automatic settings just didn't do anything.

-- Nico

On Fri, Nov 20, 2009 at 10:13 PM, Jan Ciger <jan.ciger at gmail.com> wrote:

> "Roman Grigoriev" <grigoriev at gosniias.ru> wrote:
> > Hi,Robert
> > Thanx for you reply. But you see I'm sure that under windows it's not
> >  possible to render  on two Geforce cards and nvidia guys told me that I
> >  need to buy Quadro. My app works fine and do some render but only one
> GPU
> >  calculate graphics. And in SLI mode you have only one virtual GPU
> visible
> >  to OS. And that's why I decide to move on linux. Today only CUDA can
> work
> >  on two Geforce under windows, and nvidia cuts some functionality in
> >  Geforce cards. When I run my code on linux I haven't got any speedup of
> >  using two GPUs. And that's why I ask about this subject.
>
> Roman, you can set your system up in such way that each GPU is assigned one
> X
> screen (not Twinview where you have one large desktop stretched over the
> cards). Then OSG will use two graphic contexts and render on both cards for
> sure.
>
> On the other hand, I doubt that you will see much of a speedup compared to
> a
> single card. If you are rendering for an HMD and do not have some kind of
> special, high-end high resolution one, you are most likely bound by the CPU
> and not the GPUs. Usual HMDs that I have seen have resolutions from about
> 320x240 (low end) up to about 1280x1024 (decent, expensive stuff like
> Kaiser) -
> the GPU you are mentioning should be able to cope with that easily.
>
> Regards,
>
> Jan
>
>
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>
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