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I've often wondered why Nvidia cards are generally so much better at rendering scenes in Blender's cycles renderer (a raytracing engine). The benchmarks on Blen

I've often wondered why Nvidia cards are generally so much better at rendering scenes in Blender's cycles renderer (a raytracing engine). The benchmarks on Blender's website are really telling (https://opendata.blender.org/benchmarks/query/?group_by=device_name&blender_version=3.3.0 https://opendata.blender.org/benchmarks/query/?group_by=devi...) by the fact that the only non Nvidia entry on the first page is the AMD 2X EPYC 9654 96-Core. This really lays out the decisions that Nvidia made compared to AMD and how their approach tends to hide some of the shortcoming of GPUs (latency and utilization).

zokier 4y ago
That is more of a software (ecosystem) thing. Nvidias CUDA and OptiX are well beyond anything AMD has to offer. In Cycles case, I believe that on Nvidia it is taking good advantage of RT cores while on AMD they are completely unused which has predictable effect on performance. Even ignoring the RT cores I suspect the Nvidia code path is likely far more optimized than AMD one https://www.phoronix.com/news/AMD-HIP-RT-Blender-3.5-Plans https://www.phoronix.com/news/AMD-HIP-RT-Blender-3.5-Plans
- dotnet00 4y ago
  Plus on AMD's side we have their inability to commit to fully supporting any specific system long term, limiting open source interest in doing things for them.
  - Melatonic 4y ago
    I thought AMD was all in on OpenCL?
    - dotnet00 4y ago
      Nope, their OpenCL support has been kind of stagnant for a while, especially on Windows. On top of that, part of why Blender dropped its OpenCL supporting renderer was that AMD's OpenCL was still pretty buggy, making the renderer a pain to maintain. Lately their focus is ROCm and their CUDA equivalent language, but it also has limited official hardware support and AFAIK the Windows SDK for it is still not public. Similar commitment issues have plagued their custom renderers.
      - my123 4y ago
        AMD's OpenCL driver is significantly worse than NVIDIA's since ages afaik...
        jjoonathan 4y ago
        Yep, this has been true for many years. Hopefully now that AMD has money they can turn things around. As much as it pains me to admit, giving up on OpenCL and focusing on the CUDA clone is probably the correct strategic move. OpenCL is just far too different to facilitate porting, and there's a lot of porting to do before AMD can start to take compute marketshare.
        imtringued 4y ago
        It isn't because it further fragments the market. Now you have Nvidia CUDA, AMD "CUDA", Intel oneAPI. At least Intel is building their oneAPI on top of OpenCL via SYCL which means all AMD has to do is implement a bunch of Intel's OpenCL extensions, which are far from unreasonable (for example, unified shared memory which should have been in OpenCL 2.x instead of shared virtual memory).

zokier 4y ago

That is more of a software (ecosystem) thing. Nvidias CUDA and OptiX are well beyond anything AMD has to offer. In Cycles case, I believe that on Nvidia it is taking good advantage of RT cores while on AMD they are completely unused which has predictable effect on performance. Even ignoring the RT cores I suspect the Nvidia code path is likely far more optimized than AMD one https://www.phoronix.com/news/AMD-HIP-RT-Blender-3.5-Plans https://www.phoronix.com/news/AMD-HIP-RT-Blender-3.5-Plans

dotnet00 4y ago
Plus on AMD's side we have their inability to commit to fully supporting any specific system long term, limiting open source interest in doing things for them.
- Melatonic 4y ago
  I thought AMD was all in on OpenCL?
  - dotnet00 4y ago
    Nope, their OpenCL support has been kind of stagnant for a while, especially on Windows. On top of that, part of why Blender dropped its OpenCL supporting renderer was that AMD's OpenCL was still pretty buggy, making the renderer a pain to maintain. Lately their focus is ROCm and their CUDA equivalent language, but it also has limited official hardware support and AFAIK the Windows SDK for it is still not public. Similar commitment issues have plagued their custom renderers.
    - my123 4y ago
      AMD's OpenCL driver is significantly worse than NVIDIA's since ages afaik...
      - jjoonathan 4y ago
        Yep, this has been true for many years. Hopefully now that AMD has money they can turn things around. As much as it pains me to admit, giving up on OpenCL and focusing on the CUDA clone is probably the correct strategic move. OpenCL is just far too different to facilitate porting, and there's a lot of porting to do before AMD can start to take compute marketshare.
        imtringued 4y ago
        It isn't because it further fragments the market. Now you have Nvidia CUDA, AMD "CUDA", Intel oneAPI. At least Intel is building their oneAPI on top of OpenCL via SYCL which means all AMD has to do is implement a bunch of Intel's OpenCL extensions, which are far from unreasonable (for example, unified shared memory which should have been in OpenCL 2.x instead of shared virtual memory).