[osg-users] Rendering performance issues

Adrian Egli OpenSceneGraph (3D) 3dhelp at gmail.com
Mon Jul 7 23:37:40 PDT 2008


Hi all

i just tested osgviewer with a pagedLod scene, and i got some interesting
behaviour, may zou can retest it similar:  change the threading mode with
'm'. (i am working under windows vista)

under Singlethread, the cap become much smaller.

adegli

2008/7/8 Paul Martz <pmartz at skew-matrix.com>:

>  The first image (vsyncOFF-1GPU.jpg) shows the timing rendering 1 slave
> camera on an extended (2880x900) dual-monitor on a single Nvidia card.  Note
> the 211Hz rendering rate with VSync off and the substantial Draw/GPU
> overlap.  [Note that in all of these timing tests none of the CPUs appeared
> more than 50% loaded.]  This is the type of performance I was anticipating.
>
> Now all I did was turn on Vsync.  The second image (vsyncON-app-long.jpg)
> now shows a 60Hz rendering rate as expected (with a delay after GPU waiting
> for VSync), but no Draw/GPU overlap, there's even a slight gap between the
> two?  Why is this different now?
>
> I suspect this issue is caused by the graphics card having an upper limit
> on the number of buffer swaps queued up. Once the limit of queued swaps is
> reached, the card won't start processing the next frame until it
> performs the swap for the current frame, thus causing the "gap" that you
> see. This is, of course, not an issue with vsync disabled.
>
> Not sure about the "gap" in the rest of your post; perhaps Robert has more
> info.
>
> I hope that helps,
>
> Paul Martz
> *Skew Matrix Software LLC*
> http://www.skew-matrix.com
> +1 303 859 9466
>
> _______________________________________________
> osg-users mailing list
> osg-users at lists.openscenegraph.org
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
>
>


-- 
********************************************
Adrian Egli
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