[Bf-cycles] CUDA performance tests

David Black db4tech at yahoo.co.uk
Sat May 17 19:08:58 CEST 2014

Hi Brecht,

Spent the afternoon carrying out performance tests on a heavy scene 
(lots of displacement and hair), sorry scene is test work for a company 
so unable to share.

GPGPU tests performed with an 2GB GTX 580m

Small border region render of whole scene (F12 final render)
*Blender 2.70a*
Time:02:13 Mem:1540

*Blender 2.70.4 (and .5)*
Time:10:53 Mem:1743

In case there are several accumulating factors involved (other than 
__launch_bounds__ ), after testing many Blender versions managed to 
narrow down dates, big slowdown and increased memory usage was 
introduced between 17th and 27th April.

Also, post slowdown, render preview does not begin until the 12th 
sample, thought the render and/or Blender had frozen? Synchronizing 
objects and BVH build time is also slightly slower.

Would you like me to open a bug report?

Hope above information is in some way helpful.



On 25/04/2014 16:44, Brecht Van Lommel 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.
> _______________________________________________
> Bf-cycles mailing list
> Bf-cycles at blender.org
> http://lists.blender.org/mailman/listinfo/bf-cycles

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