Type support needs to check the extensions only.

[jungpark-mlir]

OpenCL-Benchmark/src/opencl.hpp

Line 46 in a036229

is_fp64_capable = (uint)cl_device.getInfo<CL_DEVICE_NATIVE_VECTOR_WIDTH_DOUBLE>()*(uint)contains(cl_device.getInfo<CL_DEVICE_EXTENSIONS>(), "cl_khr_fp64");

Hello,

I've been learning how it works and have some questions about it.
Firstly, I'm not sure about the logic it determines the support for the data types.
I believe CL_DEVICE_NATIVE_VECTOR_WIDTH_* doesn't necessarily reflect the presence of a given type support.

The specification only says,

If double precision is not supported, CL_DEVICE_NATIVE_VECTOR_WIDTH_DOUBLE must return 0.
If the cl_khr_fp16 extension is not supported,CL_DEVICE_NATIVE_VECTOR_WIDTH_HALF must return 0.

Not the other way around.
Checking support for the double/half types only need to query cl_khr_fp64, cl_khr_fp16 extensions respectively.
Also I wonder if the other types need to be checked because they're supposed to be supported as builtin scalar type.

I might be missing something but please have a look and let me know what you think about it.

[ProjectPhysX]

Hi @jungpark-mlir,

the CL_DEVICE_NATIVE_ provide the size of the vector units which can sometimes be useful information. For Intel Arc GPUs I had to add an additional failsafe: They would happily report CL_DEVICE_NATIVE_VECTOR_WIDTH_DOUBLE = 1, indicating FP64 support, but the cl_khr_fp64 flag is missing and they don't support FP64 in hardware. Same for FP16.

The other data types are always present.

Regards,
Moritz

[lorn10]

@jungpark-mlir Just FYI, maybe you will look at some point into the new Mesa OpenCL implementation called "rusticl", - if you are on Linux. 😉 The initial support looks to be really promising.

I think Mesa's open-source "rusticl" doesn't have those restrictions which some vendor specific OpenCL implementations have. And yes also Intel seems to limit the compute capability of their hardware for whatever reason. I don't understand why those newest Intel GPU are lacking hardware FP64 support, - any software FP64 emulation would be much slower. But in the end this should have not a big relevance for gaming, - it might have one for mining. 😄