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SYCL looks nice in theory, but AMD seems determined to stay irrelevant in GPGPU. To use SYCL on AMD you use a backend that targets ROCm, which still doesn't wor

SYCL looks nice in theory, but AMD seems determined to stay irrelevant in GPGPU. To use SYCL on AMD you use a backend that targets ROCm, which still doesn't work on Windows. So why would I use that instead of Cuda and just not care about AMD's GPUs? A portable framework loses a lot of its meaning when it's not portable, and now SYCL just looks like an unnecessary layer over Cuda and OpenMP. GPGPU has been a thing for 20 years now, and I still can't easily write code that works on Nvidia and AMD and ship it to consumers on Windows. From what I've seen OpenCL seems to be dying, AMD doesn't care about compute on Windows or on their Radeon cards, and Cuda continues to be the only real option year after year in this growing segment. Why would anyone buy anything else than Nvidia if they're using Photoshop, Blender, DaVinci Resolve, or other compute heavy consumer software? Maybe it's unrealistic to hope that any library can fix this and just rename GPGPU to Nvidia compute and be done with it.

sudosysgen 6y ago
I really don't get this. You can just use a SYCL backend that compiles to OpenCL or SPIR and target AMD GPUs. I did it yesterday. Use ComputeCpp and target AMD GPUs. If you're using Blender it can absolutely make a ton of sense to use AMD hardware. For most of the time where Blender supported GPGPU AMD was the best choice, and I set up rendering servers with AMD hardware for that express purpose. I feel like a big part of this attitude is from not actually having tried it. Because SYCL works fine on AMD. In fact, you have more backend options for AMD than NVidia.
- pjmlp 6y ago
  So basically buy into what CodePlay is selling instead of what NVidia is selling.
- sorenjan 6y ago
  Which AMD cards though? It's one thing to be able to buy AMD hardware for your data center or workstations, but as far as I can see their latest consumer platform RDNA2 doesn't support ROCm [0]. Radeon DNA doesn't support Radeon Open Compute. ROCm have never supported Windows, and it doesn't look like there are any future plans for it either. And when looking at which AMD cards support SPIR or SPIR-V I can't find any good list, but I do find issues where AMD removed support in the drivers and told people to use old drivers if they needed it [1]. Compare to Nvidia where you can use any Geforce card you can find, so if you have a Nvidia GPU you know Cuda will work. If you control your own hardware and software stack maybe an AMD CDNA card is fine, but if you want to ship software to end users it seems to be difficult to even know what will work. So you use cross platform code for a worse experience on Nvidia and spotty support on AMD, or only Cuda and accept that it's Nvidia only but will give you a better experience. I haven't done a lot of GPGPU programming, but I've tried to look at it from time to time, and I've been disheartened by it every time. Nvidia's handling of OpenCL, AMD's disregard for SPIR. This is what an AMD representative had to say in 2019 [2]: "For intermediate language, we are currently focusing on direct-to-ISA compilation w/o an intervening IR - it's just LLVMIR to GCN ISA. [...] Future work could include SPIRV support if we address other markets but not currently in the plans." [0] https://github.com/RadeonOpenCompute/ROCm/issues/1180#issuecomment-746164720 https://github.com/RadeonOpenCompute/ROCm/issues/1180#issuec... [1] https://community.amd.com/t5/opencl/spir-support-in-new-drivers-lost/td-p/170165 https://community.amd.com/t5/opencl/spir-support-in-new-driv... [2] https://github.com/RadeonOpenCompute/ROCm-OpenCL-Runtime/issues/57#issuecomment-535219495 https://github.com/RadeonOpenCompute/ROCm-OpenCL-Runtime/iss...

sudosysgen 6y ago

I really don't get this. You can just use a SYCL backend that compiles to OpenCL or SPIR and target AMD GPUs. I did it yesterday. Use ComputeCpp and target AMD GPUs. If you're using Blender it can absolutely make a ton of sense to use AMD hardware. For most of the time where Blender supported GPGPU AMD was the best choice, and I set up rendering servers with AMD hardware for that express purpose. I feel like a big part of this attitude is from not actually having tried it. Because SYCL works fine on AMD. In fact, you have more backend options for AMD than NVidia.

pjmlp 6y ago
So basically buy into what CodePlay is selling instead of what NVidia is selling.
sorenjan 6y ago
Which AMD cards though? It's one thing to be able to buy AMD hardware for your data center or workstations, but as far as I can see their latest consumer platform RDNA2 doesn't support ROCm [0]. Radeon DNA doesn't support Radeon Open Compute. ROCm have never supported Windows, and it doesn't look like there are any future plans for it either. And when looking at which AMD cards support SPIR or SPIR-V I can't find any good list, but I do find issues where AMD removed support in the drivers and told people to use old drivers if they needed it [1]. Compare to Nvidia where you can use any Geforce card you can find, so if you have a Nvidia GPU you know Cuda will work. If you control your own hardware and software stack maybe an AMD CDNA card is fine, but if you want to ship software to end users it seems to be difficult to even know what will work. So you use cross platform code for a worse experience on Nvidia and spotty support on AMD, or only Cuda and accept that it's Nvidia only but will give you a better experience. I haven't done a lot of GPGPU programming, but I've tried to look at it from time to time, and I've been disheartened by it every time. Nvidia's handling of OpenCL, AMD's disregard for SPIR. This is what an AMD representative had to say in 2019 [2]: "For intermediate language, we are currently focusing on direct-to-ISA compilation w/o an intervening IR - it's just LLVMIR to GCN ISA. [...] Future work could include SPIRV support if we address other markets but not currently in the plans." [0] https://github.com/RadeonOpenCompute/ROCm/issues/1180#issuecomment-746164720 https://github.com/RadeonOpenCompute/ROCm/issues/1180#issuec... [1] https://community.amd.com/t5/opencl/spir-support-in-new-drivers-lost/td-p/170165 https://community.amd.com/t5/opencl/spir-support-in-new-driv... [2] https://github.com/RadeonOpenCompute/ROCm-OpenCL-Runtime/issues/57#issuecomment-535219495 https://github.com/RadeonOpenCompute/ROCm-OpenCL-Runtime/iss...