Hi all,
I've just received some comments from the NVIDIA driver team.
"If we didn't CPU spin in the driver and instead use the
OS-provided "waitforvblank" function, when you drive OpenGL from two
threads, you get an awful stutter & performance because one thread is
inside the OS blocking the other one from progressing until the vblank happens.
Also note that this CPU consumption by the driver is very
artificial and you will only notice on apps that do very little work per frame.
It's not like we are hogging the CPU, we do yield to other threads in that spin
loop. Bottom line: the CPU will only get used if it's idle."
Can anyone proficient regarding drivers/threading provide some feedback on
this? I'm not quite sure why a micro-sleep wouldn't work instead of a spinlock.
Thanks everyone.
Regards,
Kim.
From: k.che...@live.com
To: osg-users@lists.openscenegraph.org
Date: Mon, 21 Sep 2009 00:49:01 -0400
Subject: Re: [osg-users] OSG CPU Utilization
Hi J-S,
Thanks. I've just sent them an email now.
Regards,
Kim.
> Date: Sun, 20 Sep 2009 19:51:33 -0400
> From: jean-sebastien.g...@cm-labs.com
> To: osg-users@lists.openscenegraph.org
> Subject: Re: [osg-users] OSG CPU Utilization
>
> Hi Kim,
>
> > What does everyone suggest the way for me to make progress the fastest
> > would be? I'm assuming I will have to send them the system specs of the
> > systems that are affected, and the minimum set of files that is required
> > to reproduce the bug, along with some other miscellaneous information.
>
> I've had good results e-mailing devsupp...@nvidia.com with an example
> that reproduces the problem (binary executable, data files, and with the
> least amount of steps necessary on their part to see the problem).
>
> I've reported two bugs this way and each time it took about a week to
> get a first response and then it went quickly from there, getting
> responses generally the day after I answered their questions, until they
> confirmed the bug was fixed in the next driver (and I could confirm it too).
>
> Hope this helps,
>
> J-S
> --
> ______________________________________________________
> Jean-Sebastien Guay jean-sebastien.g...@cm-labs.com
> http://www.cm-labs.com/
> http://whitestar02.webhop.org/
> _______________________________________________
> osg-users mailing list
> osg-users@lists.openscenegraph.org
> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
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