Question 770
At the Jasperfield high-performance computing center, while planning an accelerator expansion, a large GPU node has several high-speed NIC ports but the job routes all collective traffic through one adapter. What is the most significant cause of this behavior?
Explanation
Correct Answer
This explanation matches the reported facts: unused independent network paths cannot improve throughput when communication is pinned to one rail. A corrective test should establish that a representative collective test utilizes approved rails without introducing connectivity failures. This directly addresses the reported issue at the Jasperfield high-performance computing center.
Incorrect Answers
That statement concerns storage fabric versus compute fabric; here the reported facts point to a different issue: unused independent network paths cannot improve throughput when communication is pinned to one rail. For the Jasperfield high-performance computing center, the priority is to evaluate multi-rail communication with correct NCCL and fabric configuration where supported.
Clock differences obstruct correlation of distributed events and job timeline measurements. This can occur in other projects, but it is not the primary explanation at the Jasperfield high-performance computing center.
Although data access bandwidth and availability influence whether multiple GPUs can sustain useful compute, the situation does not describe that specific cause; it instead indicates that unused independent network paths cannot improve throughput when communication is pinned to one rail. For the Jasperfield high-performance computing center, the priority is to evaluate multi-rail communication with correct NCCL and fabric configuration where supported.