Re: opencl-icd virtual package(s)?
On Sun, 2023-06-18 at 10:37 +0800, Paul Wise wrote:
> [BCCed to OpenCL ICD implementation package maintainers]
>
> I noticed that some packages have a dep on specific OpenCL ICD
> packages, but don't dep on the opencl-icd virtual package(s).
> Presumably any of the OpenCL ICDs work for most packages?
Theoretically any of them is expected to work. That's the point of ICD.
But, while I'm not an OpenCL user, I have heard that different OpenCL
implementations have their own quirk... (forgotten source)
> $ grep-aptavail --no-field-names --show-field Package --field
> Depends,Recommends,Suggests --whole-pkg '(' --pattern .*opencl-icd.* --
> and --not --pattern '^opencl-icd(-1\.[1]2-1)?$' ')'
>
> In addition, I noticed that hashcat-nvidia (which presumably doesn't
> need to depend on the opencl-icd virtual package) only depends on two
> of the nvidia OpenCL ICD packages, while there are lots of other nvidia
> OpenCL ICD packages that presumably work too.
It won't surprise me if .*-nvidia fails to work with a non-nvidia OpenCL
implementation.
> I have attached a package list and dd-list for these issues.
>
> Perhaps there should be a default-opencl-icd virtual package?
Usable OpenCL implementation is very device specific. We cannot make
sure what OpenCL implementation will always be avaialble on user devices,
and even our buildd.
If there must be a default, pocl-opencl-icd is the solution. It supports runing
OpenCL kernels on CPU, so it should be working on most hosts.
Just don't expect any higher performance from CPU-based OpenCL.
FYI: to verify what OpenCL is usable on your host, you may just
$ sudo apt install clinfo; clinfo
> Perhaps lintian should flag situations where the dep isn't just
> default-opencl-icd | opencl-icd? or is missing opencl-icd?
>
> Thoughts?
I think the current status for some typical packages, like python3-pyopencl
is already correct.
$ apt show python3-pyopencl
Depends: ..., pocl-opencl-icd | mesa-opencl-icd | opencl-icd, ...
You see pocl there as the first choice. For any other packages
that depend on opencl, I think maintainers might have an idea
on what opencl implementation is preferred, either inclusively
or exclusively.
> PS: I noticed this because beignet-opencl-icd is RC-buggy. This is the
> only OpenCL ICD implementation package I can see that supports Intel
> Ivy Bridge, but it is hard to tell which other packages support this,
> because some descriptions don't mention which hardware is supported.
It looks the intel-opencl-icd does not support very old CPUs,
(as listed here https://github.com/intel/compute-runtime )
but I think most major users of OpenCL depends on dedicated GPUs.
The performance of integrated graphics seems no different than nothing.
I think all OpenCL ICD providers can be found by $ apt search opencl-icd .
The AMD opencl implementation is missing.
It is a part of ROCm (https://github.com/RadeonOpenCompute/ROCm-OpenCL-Runtime ),
and indeed something to work on for the ROCm team <debian-ai@l.d.o> in the future.
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