Optix 3.9.1 vs 5.0.0 pathtracer samples performance


I’m having trouble figuring out why there is a big performance difference at startup of the Optix 3.9.1 sample projects compared to 5.0.0.

In my tests the difference is big, in the pathtracer example using 3.9.1 runs in 2 seconds, in 5.0.0 runs in 22 seconds.

Any reason for this difference?

My system
Windows 10
NVidia GPU 650M
Dirver 385.54

I’m unable to reproduce this on my current development configuration (Quadro P6000, Win10-64 1607, 397.64 drivers) with the precompiled SDK examples.
Either the OptiX 3.9.1 path_tracer.exe, the OptiX 5.0.0 optixPathTracer.exe, or the current OptiX 5.1.0 optixPathTracer.exe starts in under 2 seconds.

Have you by chance enabled OptiX exceptions inside the slower application?
At OptiX 4 the internal kernel compiler was completely rewritten to use LLVM and that will take a lot longer when generating the code for the exception handling than in previous versions.

That said, when switching to an OptiX 5 version, please note that OptiX 5.1.0 has just been released last week and that also contains changes to improve startup times in general.

Also the optixPathTracer inside the SDK is a very limited example. For some more elaborate path tracer implementation have a look at the sticky post in this sub-forum explaining the new additions to the OptiX Advanced Samples on github.

Hi Detlef.

I did other tests without debug and in fact the problem is there. I will try apply the upgrade to 5.1.0 in my renderer and see what happens.


Note: The AI Denoiser is amazing, I’d really like to know how the algorithm works because I built a denoiser using bilaterial filtering on separated maps (DL, IL, Reflection, Refraction) and got really good results, but not comparable in performance

You can find a lot more information on Deep Learning Denoisers here: https://developer.nvidia.com/optix-denoiser

There’s also at least one Deep Learning Institute course about that here: https://developer.nvidia.com/dli/onlinelabs

I’ve just pushed a new OptiX Introduction example to the OptiX Advanced Samples github repository which shows how to the use the new HDR DL Denoiser in OptiX 5.1.0.