cuda-python conda packages should avoid depending on the entire CUDA Toolkit about cuda-python

[vzhurba01]

Release v12.1.0 trims Conda dependencies to only require NVRTC and CUDART (excluding math libraries). Closing.

[leofang]

cuda-cudart is not needed at runtime, as currently the cudart layer in CUDA Python is a reimplementation of cudart. So just NVRTC.

[jakirkham]

Would the cuda-cudart package be sufficient? Or is more needed than that?

[bdice]

@jakirkham I think building the package requires CUDA headers (so -dev packages for cuda-cudart-dev and cuda-nvrtc-dev). At runtime, perhaps only cuda-cudart and cuda-nvrtc are needed?

The features depending on cudaProfiler.h are not brought in as a dependency of cuda-cudart and thus must be explicitly depended on via cuda-profiler-api at build time.

[jakirkham]

Thanks all! That sounds reasonable. Let's see if @vzhurba01 & @m3vaz have more thoughts 🙂

[vzhurba01]

As pointed out, building the package requires CUDA headers. The headers parsed are:

cuda-python/setup.py

Line 37 in 9ac2d31

header_dict = {

For building, the headers can be categorized into 3 groups:

1. Required to build
2. Optional to enable features
3. Always enabled

(1) Referenced by extern from, list by @bdice looks complete
(2) Not used right now
(3) cuda_profiler_api.h and graphics APIs (EGL, GL, VDPAU)

For runtime, the requirements are:

1. NVRTC is needed if you use NVRTC
2. CUDART is needed if you build kernels referencing some CUDART types

(2) Many types are built-in though, but not all. One of the ported examples/samples encounter such a scenario.

Perhaps (2) can be limited to only the built-in types, and remaining dependency if needed can be added by users?

[bdice]

I would be happy to keep cudart and nvrtc as “hard” runtime dependencies to ensure the package is fully functional. The main parts I want to strip out are the rest of cuda-toolkit that make it very large, like math libraries.

How should we go about making this change? The conda-forge side can simply use this dependency list. We’ll want to reflect the same set of dependencies for the nvidia channel version and issue a new version (or a new build of the same version).

[jakirkham]

Thanks Vlad! 🙏