Don, have you tried this on a Quadro, or just a GeForce? It seems like the kind of issue NVIDIA would have addressed on their workstation-class devices. -Paul
-----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Robert Osfield Sent: Tuesday, October 17, 2006 2:59 AM To: osg users Subject: Re: [osg-users] Multi-window performance Hi Don, I run with two windows, one on each of my 7800GT cards at a solid 60Hz without any problems, performance doesn't drop when I run on one card with one window, to two windows on two cards - the multi-threading all works pretty smoothly. I have see the performance drop you talk of when using two windows on the same graphics card though, is this the problem area you are thinking of? Robert. On 10/16/06, Don Burns <[EMAIL PROTECTED]> wrote: > I just had a lightbulb go off. > > For a long time I've been scratching my head about multi-window > performance with osg examples. It seemed that whenever I used two > windows (or more) the performance suffered for no apparent reason. > For example, rendering the cow (the graphics card equivalent of a drop > in the bucket), on a camera configration that uses two RenderSurfaces, > caused my frame rate to go from 60 hz, to 30 hz (or full screen refresh rate to 1/2 screen refresh rate). > > I've just realized what that reason is. In a meeting not too long > ago with Nvidia, I was told that the NVidia driver imposed a block > within Swapbuffers if you are two frames ahead. I was told that this > was done to "maximize pipelining" within the graphics chip. I > objected to this based on various reasons, not the least of which is > that I want frame control in the application, not in the graphics driver. > > So, what is happening here is that for every frame of an application > using two windows, in which we are issuing Swapbuffers for each > window, we are being blocked twice waiting for vertical retrace. > > Does this ring a bell with anyone else? I need to do some deeper > testing to confirm this, but it is an issue I'd like to take up with > NVidia if the ball is in their court here. > > -don > > _______________________________________________ > osg-users mailing list > [email protected] > http://openscenegraph.net/mailman/listinfo/osg-users > http://www.openscenegraph.org/ > > _______________________________________________ osg-users mailing list [email protected] http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/ _______________________________________________ osg-users mailing list [email protected] http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
