[Bf-cycles] CUDA performance tests

Brecht Van Lommel brechtvanlommel at pandora.be
Sat Apr 26 15:33:59 CEST 2014

For the two cards I have here, it seems that after tweaking the code,
CUDA 6.0 performance is similar to previous releases with 5.0. There's
no improvement and even some small slowdown, but we actually had to do
quite a bit work since 5.5 was released to even get it to that point,
and some features have been added in the meantime. Overall I think
it's acceptable if other cards show similar results.

The patches are from an earlier test I did with the CUDA 6.0 beta,
based on feedback from NVidia. They help on sm_30 and sm_35, but not
sm_20 and sm_21 (these changes were also tested on 480 GTX and Tesla
K20m). So it seems we should enable them for sm_3x if we switch to
CUDA 6.0.

We need to test more cards and platforms, comparing latest master +
CUDA 6.0 to the 2.69 and 2.70a releases, before we can make a


On Fri, Apr 25, 2014 at 5:44 PM, Brecht Van Lommel
<brechtvanlommel at pandora.be> wrote:
> Hi all,
> We're having some trouble with CUDA performance at the moment, with in
> a performance regression on Titan cards compared to 2.69, and unclear
> effects from recent changes. Further there's the new CUDA 6.0 toolkit,
> which we ideally could move to, as sticking to 5.0 is a problem with
> newer compilers.
> We could use some help testing all this, especially for Titan cards as
> I don't have one of those.
> There's a google doc here:
> https://docs.google.com/spreadsheets/d/1IKvO6s7h_0oVGbGE3giowx2fBvyXzIfdM3qCSfROJfI
> For now I'm assuming someone with a Titan card can make own builds to
> test these git revisions. If not we can build and upload binaries to
> test.
> The test is:
> * download: http://www.pasteall.org/blend/28679
> * run: ./blender -b modified_bmw.blend -f 1
> If you've got a different .blend file that is giving performance
> regressions, or you find different behavior when rendering in the UI
> rather than command line, then results from that are welcome too.
> The information that I'm looking for from this is especially:
> * Which revision caused the Titan performance regressions?
> * Is CUDA 6.0 performance acceptable to us for the next release?
> * Were there significant performance regressions due to recent changes?
> * Which effect do the two provided patches have when building with CUDA 6.0?
> Thanks,
> Brecht.

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