Dear Mr. Art,
I too am noticing a problem similar to what Mr. Thorsten pointed out. Just
curious about if the openGL and CUDA going together, I downloaded the osg2.9.10
and osgCompute nodekit. I have CUDA 3.2 installed with on my machine Core2Duo
with GEForce. The osgGeometryDemo sample code for warping with cow.osg is
giving
a reasonably high frame rate. I thought I should share this in case it is of
any
help.
Regards
Harash
________________________________
From: J.P. Delport <jpdelp...@csir.co.za>
To: OpenSceneGraph Users <osg-users@lists.openscenegraph.org>
Sent: Mon, January 3, 2011 3:30:34 PM
Subject: Re: [osg-users] osgPPU CUDA Example - slower than expected?
Hi,
I don't have any other suggestions than to use a GL debugger to make
sure nothing is going to CPU or to try the new CUDA functions in osgPPU
or your own code. I remember something in the GL to CUDA stuff bugging
me, but cannot remember the details. AFAIR something was converting from
texture to PBO and then to CUDA mem.
jp
On 16/12/10 13:25, Thorsten Roth wrote:
> Hi,
>
> as I explained in some other mail to this list, I am currently working
> on a graph based image processing framework using CUDA. Basically, this
> is independent from OSG, but I am using OSG for my example application :-)
>
> For my first implemented postprocessing algorithm I need color and depth
> data. As I want the depth to be linearized between 0 and 1, I used a
> shader for that and also I render it in a separate pass to the color.
> This stuff is then fetched from the GPU to the CPU by directly attaching
> osg::Images to the cameras. This works perfectly, but is quite a bit
> slow, as you might already have suspected, because the data is also
> processed in CUDA kernels later, which is quite a back and forth ;-)
>
> In fact, my application with three filter kernels based on CUDA (one
> gauss blur with radius 21, one image subtract and one image "pseudo-add"
> (about as elaborate as a simple add ;-)) yields about 15 fps with a
> resolution of 1024 x 1024 (images for normal and absolute position
> information are also rendered transferred from GPU to CPU here).
>
> So with these 15 frames, I thought it should perform FAR better when
> avoiding that GPU <-> CPU copying stuff. That's when I came across the
> osgPPU-cuda example. As far as I am aware, this uses direct mapping of
> PixelBuferObjects to cuda memory space. This should be fast! At least
> that's what I thought, but running it at a resolution of 1024 x 1024
> with a StatsHandler attached shows that it runs at just ~21 fps, not
> getting too much better when the cuda kernel execution is completely
> disabled.
>
> Now my question is: Is that a general (known) problem which cannot be
> avoided? Does it have anything to do with the memory mapping functions?
> How can it be optimized? I know that, while osgPPU uses older CUDA
> memory mapping functions, there are new ones as of CUDA 3. Is there a
> difference in performance?
>
> Any information on this is appreciated, because it will really help me
> to decide wether I should integrate buffer mapping or just keep the
> copying stuff going :-)
>
> Best Regards
> -Thorsten
> _______________________________________________
> osg-users mailing list
> osg-users@lists.openscenegraph.org
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>
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