Hi Robert, We normally run with vsync on, but for these tests we turned it off so we could observe frame rates greater than 96 FPS.
We ran some sanity tests, with vsync on, CullDrawThreadPerContext threading and both with and without OSG_SERIALIZE_DRAW_DISPATCH=OFF, but the results were largely the same. Our next step will be to try mosaic mode as suggested by both Wojtek and some folks from Nvidia. We'll create one big window that covers all four cards and open 4 viewports on it, one viewport per card, and see what the performance is. Thanks, John On Fri, 8 Oct 2010, Robert Osfield wrote:
Hi John, I haven't run with multiple cards for a little while, but when I've done it in the past I certainly didn't have the scaling problems you are seeing. Like Wojtek I'd suspect the OpenGL driver is trying to serialize the swap buffers even though the OSG is attempting to run them from separate threads. As a sanity test try running the app with CullDrawThreadPerContext, this will only require 5 threads, but since you are getting 150fps frame rate to begin with not separating Cull and Draw into different threads shouldn't affect performance too much. Using less threads on the OSG side might give the OS and driver a bit more breathing space. I'd also suggest enabling vysnc to see what the driver makes of it - this is how you should be deploying your app, and is the way you should conduct most of work, disabling vysnc is only something I'd recommend for very specific types of performance profiling. Robert. _______________________________________________ osg-users mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
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