Hi Robert,

I couldn't find the cause or any workaround.  I tried a range of
things to try and characterise and track down the cause of bug but
came away without any better idea then when I started.  In
osgViewer/View.cpp I implemented proper setup of the number of context
supported by the scene which was one bug, but this didn't effect the
crash we are seeing with many contexts open.  I don't know what else
to try on the OSG side, and suspect a driver bug.

That's a shame.

I might try submitting the modified example to nvidia to see if they can confirm a bug. By coincidence, I just recently read their developer FAQ, and they say they generally don't need the source, just a sample application they can run to replicate the problem (I guess they run debug drivers and can trace through what the driver is doing).

http://developer.nvidia.com/object/General_FAQ.html#G1
__________________________________

If the reference rasterizer results differ from the HAL results, then please get in touch with us. We will fix the problem as soon as possible. However, we will need the following information:
    * Operating system
    * Driver version
    * Graphics card
    * A sample application that clearly demonstrates the problem. We do
      not need source in general, and we are happy with reasonable
      complex apps (i.e., no need to narrow the problem down as long as
      the problem is clearly demonstrated). What is most important is
      that the problem is easy to reproduce, and that the application is
      self-contained. An application that goes straight to the problem
      is best (i.e., a "single-click" application that doesn't require
      navigation to get to the problem).
__________________________________


A different tack completely would be to use SingleThreaded and
implement swap groups so that all the windows swap at the same time.
This would like fix the performance issues and avoid problems with
thrashing the drivers so hard.  For your particular usage model the
only reason that you are using threading is that the driver is
swapping on each swap call sequentially, not that you have multiple
GPU's that you want to drive multi-threaded.

Hmmm, I'll have to look around for information on swap groups. But won't my cull/draw performance be lower in SingleThreaded for large scenes, since OSG won't overlap the cull of frame n-1 with the draw of frame n?

Thanks for looking into this.

J-S
--
______________________________________________________
Jean-Sebastien Guay    jean-sebastien.g...@cm-labs.com
                               http://www.cm-labs.com/
                        http://whitestar02.webhop.org/
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