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OpenCL for Rust

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Shared Virtual Memory (SVM) support?

itayw opened this issue · comments

commented

Thanks for this library, awesome work!

I've been using it for a while now and one of the features I wanted to use is shared virtual memory. I'm currently already using host memory for my buffer, but writing and reading it pose an overhead.
From what I read and some examples I understand SVM may offer a higher efficiency due to removing this need (depending on the actual capabilities of the device).

I'm not sure my understanding is correct, but does this library offer such capabilities?

commented

To be honest my memory of the details of this is a bit foggy but anything provided by the OpenCL API should be supported by this library (depending on OpenCL version of course).

The buffer creation options are where you want to look. The memory options are passed as part of the 'flags' parameter when constructing a buffer.

https://registry.khronos.org/OpenCL/sdk/1.2/docs/man/xhtml/clCreateBuffer.html
https://registry.khronos.org/OpenCL/specs/opencl-2.1.pdf#page=104
https://docs.rs/ocl/latest/ocl/builders/struct.BufferBuilder.html#method.flags

commented

The CL_MEM_USE_HOST_PTR, CL_MEM_ALLOC_HOST_PTR flags are basically what you want. From what I remember their exact behavior varies from device to device but on CPU based systems it would be the equivalent of shared virtual memory.