On Tue, 2006-10-17 at 03:18 -0600, Paul Martz wrote: > 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
I'm not sure what kind of access you guys have to various video cards, but I've got a Quadro 2500M if anyone needs me to run anything to help test w/ this... > -----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/ > _______________________________________________ osg-users mailing list [email protected] http://openscenegraph.net/mailman/listinfo/osg-users http://www.openscenegraph.org/
