To enable SHARP (Scalable Hierarchical Aggregation and Reduction Protocol) aggregation using theNCCL-SHARP plugin, the following two environment variables are required:
NCCL_COLLNET_ENABLE=1
Enables NCCL’s support for CollNet (Collective Network) operations, including SHARP.
NCCL_SHARP_AUTOINIT=1
Automatically initializes the SHARP plugin when available, activating SHARP-based collectives.
From theNVIDIA NCCL User Guide – SHARP Plugin Section:
"NCCL_COLLNET_ENABLE must be set to enable collective network acceleration features."
"NCCL_SHARP_AUTOINIT enables automatic SHARP plugin integration at NCCL runtime."
Incorrect Options:
B. NCCL_ALGO=CollNet– This variable controls the algorithm used for collectives but does not enable SHARP.
C. NCCLSPECTRUM_ENABLE– This is not a documented NCCL variable.
Chosen Answer:
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