[osg-users] CPU Performance issues with AMD 2700 vs Intel Corei7 4770S

[Robert Osfield]

Hi Chirs et. al.

On Wed, 3 Apr 2019 at 13:08, Chris Hanson <xenon at alphapixel.com> wrote:
>   He's GPU side. I tech-reviewed for the OpenGL SuperBible that he was one of the authors of.
>
>   He might still be able to advise us on troubleshooting if we can't pin it down. He's been very helpful before.

Thanks for the info.  For now I've got the new system working well
enough that I can get on and use it as my main dev system.  With the
changes of the set up today I've got the VSG performing inline with my
expectations.

On the OSG side, ouch it's struggling far more than I expected.  I've
tried different CPU affinity tests using taskset and different
compilers and AMD zen compile options and haven't see the gap close
between the Intel and AMD.  From the CPU scene graph tests I've done
it really looks like the OSG heavy-weight node approach shows a far
bigger penalty on AMD vs Intel.  Credit to Intel for having a CPU
architecture that can handle such an awkward beast.  AMD clearly
haven't optimized the CPU architecture for software like the OSG.

As may "day job" is now pushing on with VSG and OSG is in maintenance
mode I am inclined to take note of this finding on the OSG side, but
to not spend further time trying to find improvements for the OSG on
AMD.

For users hitting up against CPU scene graph bottlenecks, especially
on AMD, then I would suggest that VSG will be the most effective way
to resolve them.  However, the VSG is still a long way from being
ready to be used in serious graphics application, it's under heavy
development and large API changes each month.  Another 6 months things
will become more viable on the VSG side as we close in on 1.0, it'll
still be quite a different API to the OSG so not a straight forward
drop in replacement.  At this point knowing that the VSG is going to
be available and will radically improve performance should make it
something to watch and plan for, especially for new projects.

Cheers,
Robert.