[Bf-cycles] Differences between svm and osl performance relatd to texture filtering?
martijn.berger at gmail.com
Sun Jul 7 11:39:16 CEST 2013
I did some quick tests to empirically test the hypothesis that osl
performance is made much worse by texture filtering or translation of
First texture filtering:
I made a scene with a plane, a camera and an environment of a solid color:
I added a texture and measured:
svm: OSL: modified OSL:
0:12:40 0:27:72 0:26:60
0:12:40 0:27:90 0:26:75
0:12:40 0:28:03 0:26:53
modified OSL is a one line change to force bi-linear texture interpolation:
intern/cycles/kernel/osl/osl_services.cpp: ~ line 772 add:
options.interpmode = TextureOpt::InterpBilinear;
I am getting what looks like a measurable significant result but no where
near what we need to explain performance gap.
both of the above are in line with each other both would indicate a
performance loss of about 25 % on using OSL for trivial shaders due to
translation of data, OSL initialization etc.
To me it seems that image textures are getting a huge hit and that the
SmartBicubic filter is not the main problem.
Hope this info helps. I am continuing the dig to find the root cause.
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