Out-Of-Box Native GPU Allreduce

NVIDIA HPC-X Software Toolkit Rev 2.19.0

This feature enables UCC library to detect the NVIDIA NVLink topology and select the best GPU-based algorithms for supported collectives (Allgather/v, Reducescatter/v).

To view the NVLink topology, run nvidia-smi topo -m

To activate this feature, make sure to enable the hierarchical component in UCC using the UCC_CLS environment variable as follows:

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UCC_CLS=basic,hier.

To view all available UCC items and options, run ucc_info -f

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