[Openmp-commits] [PATCH] D132660: [openmp][amdgpu] Implement target_alloc_host as fine grain HSA memory

[Jon Chesterfield via Phabricator via Openmp-commits]

JonChesterfield added a comment.

The semantics of 'fine grain host memory' are read/write from host or from a GPU. This uses a memory pool that will work from any GPU, we could instead use the (currently dead? weird) DeviceFineGrainedMemoryPools field if the localised-to-gpu behaviour is preferred, that's probably more efficient.

There are some other memory interfaces, e.g. llvm_omp_target_alloc_shared, but I'm having a rough time working out what the behaviour of each is supposed to be. This patch is therefore based on nvptx mapping TARGT_ALLOC_HOST onto cuMemAllocHost. There's also ALLOC_SHARED, which maps to cuMemAllocManaged, which doesn't obviously have anything to do with cuda shared memory. I can't tell what the difference between cuMemAllocHost and cuMemAllocManaged is so maybe 'fine grain hsa' will work for 'TARGET_ALLOC_SHARED' as well.


Repository:
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https://reviews.llvm.org/D132660