Question 370
An infrastructure administrator receives the following incident: An engineer benchmarks NCCL with only two GPUs on an eight-GPU HGX node, then assumes its result validates every NVSwitch interconnection. Which measured result most directly proves that this specific problem is resolved?
Explanation
Correct Answer
This is the measurable acceptance result for the described case: All eight accelerator identities participate and the topology/bandwidth report shows no inaccessible subset or failed peer link. It validates the corrective operation (Expand single-node NCCL tests to the expected full GPU participation and supported collective patterns.) rather than a related but different system check.
Incorrect Answers
This observation would help verify a different incident: After a GPU tray replacement, CUDA kernels run normally but NCCL tests between certain device pairs fail with fabric or peer-access errors. It does not directly establish the required result for the current case: All eight accelerator identities participate and the topology/bandwidth report shows no inaccessible subset or failed peer link.
This observation would help verify a different incident: NCCL performance on one server drops after a firmware update while individual GPU memory and compute tests remain steady. It does not directly establish the required result for the current case: All eight accelerator identities participate and the topology/bandwidth report shows no inaccessible subset or failed peer link.
This observation would help verify a different incident: A night-long NCCL burn-in crashes on one rank, yet the operator reruns only successful nodes and presents the new partial result as full-cluster acceptance. It does not directly establish the required result for the current case: All eight accelerator identities participate and the topology/bandwidth report shows no inaccessible subset or failed peer link.