GPU support

[TheArcaneBrony]

Is your feature request related to a problem? Please describe

I'm trying to implement a simple CDN that supports resizing images. Some parameters (ie. resizing to 2048x2048 for GIFs) causes long stalls (sometimes minute+).
I know GPU support was removed many versions ago, but would be useful on my development machine ,as testing causes my system to run out of memory as the process allocates 16GB+ of memory. (This is with multithreading, Magick.NET-Q16-HDRI-OpenMP-x64)

I feel like I'm using the right version of Magick.NET, as I intend to support HDR images and the likes.

Describe the solution you'd like

Way to optionally enable GPU acceleration for a given operation.

Describe alternatives you've considered

Multithreading (already in use), or avoiding it to reduce memory pressure (adds minutes to processing time).

Additional context

No response

[dlemstra]

There is still GPU support but that will not really solve all your memory issues. You can turn it on by setting OpenCL.IsEnabled to true.

[TheArcaneBrony]

Hm, is it possible enabling this under Linux with an AMD graphics card (standard amdgpu drivers) does nothing, at least for resizes?
Not seeing any GPU usage after enabling it.

[dlemstra]

It might be possible that the benchmark determined that your CPU is faster. You can use OpenCl.SetCacheDirectory to make sure that you know where the benchmark and compiled kernels are saved to. But I suspect that libOpenCL.so is not installed on your system.

[TheArcaneBrony]

Made sure that libOpenCL.so is available via LD_LIBRARY_PATH (as I did with OpenMP), seems to not be writing to that directory regardless?
Or is there differing behavior between how OpenMP and OpenCL are loaded that might cause this?

[dlemstra]

This will probably require some debugging but that would probably mean that you would need to build your own version of the Magick.Native library.