This really has little to do with draw instanced. The "draw" time in the stats display uses a host clock to display the elapsed time taken by the (essentially) SceneView::draw() method. The "GPU" time displays a timer value obtained from OpenGL using an NVIDIA extension (if I understand correctly). Since the two timings come from different sources, I'd expect some disparity.
So, in other words, "draw" and "GPU" are related logically, and it's convenient for us to think of them as nearly identical. But the values displayed come from two completely different sources. Paul Martz Skew Matrix Software LLC http://www.skew-matrix.com +1 303 859 9466 -----Original Message----- From: osg-users-boun...@lists.openscenegraph.org [mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of Riccardo Corsi Sent: Thursday, May 21, 2009 11:00 AM To: OpenSceneGraph Users Subject: Re: [osg-users] Problem with drawInstanced Hi again, and thanks both for your replies. It's actually a fill-rate problem, as reducing the window size I get a strong 60Hz. With the latest nVidia driver I obtain slightly better result by the way. What I still don't get exactly is: why the draw time is stuck at 15/16ms even when the GPU time is very short (about 3ms), and there's no fill rate problem? From what you explained Robert, I agree that the draw thread is somehow stuck waiting for the GPU, when it doesn't scale with the fill rate. But I'd expect the draw time to decrease when the GPU performs well. Also, I've noticed that the draw time increases with the number of instances that I send to OpenGL. Is this another parameter to take into account? Thanks, Ricky On 21/05/2009 17.33, Robert Osfield wrote: > Hi Ricky, > > On Thu, May 21, 2009 at 4:20 PM, Riccardo Corsi<riccardo.co...@vrmmp.it> wrote: >> Also GPU time increases, but that's probably due to a poor fill-rate >> of my graphics board - and it's not as killing as the draw time. >> >> What does it depend on? > > It does sounds like a fill rate issue. The draw traversal must be > growing because the GPU is not coping with the amount of overdraw that > is present when you zoom and look at a shallow angle - so it the draw > thread ends up blocking on a a full OpenGL FiFO. > > A good check for fill limit is to reduce the window size, if the frame > rate goes up then you're almost certainly fill limited. > > Robert. > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph. > org _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
