Cycles much worse performance with RTX cards

General Forums Blender Development Discussion
81

That obscure flag is:

debug-value = 256
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82

This has nothing to do with OpenCL versions - Cycles is using openCL 1.2, which to my knowledge is fully supported by NVIDIA. LuxCoreRender and ProRender demonstrate that OpenCL on NVIDIA doesn’t have to be slow either.

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I really don’t like to see this thread turning into endless argument.

For users who recently switched to RTX cards, set the preference to CUDA and use the latest Blender software, it should fix the performance issue.

Enjoy

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So then is the performance drop when using opencl with nvidia cards strictly a bug? I don’t really use prorender or luxcore, so i wasn’t even aware nvidia’s opencl performance was better in those engines.

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Don’t worry skw develops for cycles, so he does know more when it comes to whats a bug and whats a hardware issue. I wouldn’t start any argument concerning that with him.

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I would guess that it’s a matter of optimization. Since Cycles+CUDA works well and stable, there is little incentive for anyone to work on OpenCL/NVIDIA. It would take weeks if work and at best, there would be no tangible benefit for the user.

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If forcing nvidia cards to use opencl isn’t necessary for using them to render a scene alongside amd cards, then the only other benefit I can think of is an ideological one, where you don’t want to use an api that is vendor locked.

As you’ve said, cuda works well, so there isn’t really a reason to give opencl optimization on nvidia cards more priority over other improvements atm.