[osg-users] SMP and osgprerendercubemap on Linux

[Pete Carss]

Cheers Robert,

Sweet! I ran osgprerendercubemap --pbuffer - just as a preliminary test 
- and we're back up to > 60 fps - cheers....

Still doesn't explain why I only saw it with an SMP kernel - is it a 
threading issue...?

Pete



Robert Osfield wrote:
> Hi Pete,
> 
> Try using pbuffer rather than FBO, NVidia's Linux OpenGL drivers
> handling of FBO'd cubemaps broke performance wise about six months
> ago.  Switch back to Pbuffer fixes the performance issue even though
> it introduces a copy texture operation.
> 
> Unfortunately I haven't yet exposed an option to View::setUpView*() to
> allow one to require an pbuffer rather than a FBO.  You could tweak it
> by hand though and see how you get on.
> 
> Robert.
> 
> On Sat, Mar 1, 2008 at 3:55 PM, Pete Carss <peter.carss at plymouth.ac.uk> wrote:
>> Hello All,
>>
>>  I posted about this a couple of weeks ago, but didn't have much info.
>>
>>  I'm getting really poor framerates ( < 10 )from our software which is
>>  based on osgdistortion on a Core 2 Quad machine with a Quadro 3500
>>  running Ubuntu 7.10.
>>
>>  My P4 + Quadro 3450, and my Core 2 Duo + Quadro 1600M laptop run the
>>  software fine (also Ubuntu).
>>
>>  I upgraded the Core 2 Quad to Ubuntu 8.04 (to match the P4) and the
>>  problem went away. The other day I noticed that the Core 2 Quad could
>>  only see one of its cores - I upgraded to an SMP kernel, and the problem
>>  came back.
>>
>>  In the last 2 days I've been experimenting with Fedora + CCRMA -
>>  interestingly with an SMP kernel, it exhibits exactly the same
>>  behaviour. I don't see this behaviour under FreeBSD (6.2 and 7.0).
>>
>>  I see this behaviour with osgdistorion --dome, and also osgprerendercubemap.
>>
>>  I suspect that this is a Linux/SMP problem rather than an OSG problem,
>>  but I thought you guys might have seen this behaviour, or know
>>  workarounds...
>>
>>  Pete
>>
>>
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