HMEM Copy Callbacks #146
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HMEM Copy Callbacks #146
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Signed-off-by: James Dinan <jdinan@nvidia.com>
Signed-off-by: James Dinan <jdinan@nvidia.com>
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Libfabric already has GDRCopy support plumbed, so this patch is a temporary workaround for providers that haven't hooked up to this support. Should not be any need to carry these changes upstream in aws-ofi-nccl. Closing this PR as do not merge. |
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Issue #, if available:
None
Description of changes:
This PR adds HMEM copy callbacks that use GDRCopy to perform memory copies. This allows aws-ofi-nccl to support providers that copy data between device and host buffers from using
cudaMemcpy. Because NCCL kernels are running on the GPU, submitting memcpy work to CUDA can (and usually does) result in a deadlock. GDRCopy can be used for such copies without introducing the risk of a deadlock. This change required the introduction of a GDRCopy buffer registration management layer (called hcopy) and a refactor of the MR handle in aws-ofi-nccl so that it can hold both the OFI and GDRCopy registration information for the buffer. GDRCopy callbacks are enabled at compile time by configuring with--with-gdrcopy=....Note, this PR is based on top of #145.
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.