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Add decription for regIsGlobal in the NET API documentation

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Sylvain Jeaugey 2024-06-14 01:54:43 -07:00
parent ab2b89c4c3
commit 529ee691c3
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ext-net/README.md
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@ -209,6 +209,16 @@ set to `NCCL_PTR_HOST|NCCL_PTR_CUDA`, otherwise it should be set to `NCCL_PTR_HO
supports `dmabuf`, it should set `ptrSupport` to `NCCL_PTR_HOST|NCCL_PTR_CUDA|NCCL_PTR_DMABUF` and
provide a `regMrDmaBuf` function.
The `regIsGlobal` field allows NCCL to register buffers in advance using e.g. a loopback connection
and later on, expect that another registration on a buffer contained within a previous registration
will be nearly immediate, as the buffer is already known by the network adapter. A typical
implementation would maintain a registration cache; the call to ncclCommRegister will create the
initial entry in the cache using regMr() on a loopback connection. Any later call to NCCL
operations will call regMr() again on the real connection, with the real buffer (could be at a
different offset within the original buffer, with a smaller size, etc), then deregMr() right after.
The call to ncclCommDeregister should call the final deregMr() and effectively remove the mapping
on the network adapter.
The `speed` field indicates the speed of the network port in Mbps (10^6 bits per second). This is
important to ensure proper optimization of flows within the node.