rdma

Compare host-staged and direct GPU-to-NIC transfers, count traffic at each boundary, and check transport selection before blaming a slow collective on missing GPUDirect.

Diagnose a multi-node regression by comparing host and GPU transfer paths, active registration mechanisms and the tested software stack.

Choose between supported InfiniBand and RoCE designs using workload tests, congestion behavior and a complete cost model.

Trace registered-memory access and GPU staging, then compare RDMA with sockets using measured CPU and application performance.

A fabric address, an RDMA device and a working GPU-memory registration path are separate requirements. Verify each inside the pod, then test the actual GPU-to-NIC placement and collective behavior.