The NIC symmetry test warns users about nodes that unexpectedly have down NICs, so they don’t wonder later why they got strange performance. In your case, when other code in MPICH decides that one of the nodes has two NICs, it causes the symmetry test to fail. A fix to that other code should cause the symmetry test to pass. — Michael Raymond HPE HPC programming environment From: Kevin Buckley via discuss <[email protected]> Date: Tuesday, March 10, 2026 at 20:33 To: [email protected] <[email protected]> Cc: Kevin Buckley <[email protected]> Subject: Re: [mpich-discuss] How does MPICH dtermine available NICs? This Message Is From an External Sender This message came from outside your organization. On 2026/03/10 23:34, Raymond, Michael wrote:

The NIC symmetry test is specific to HPE Cray MPICH.

Cheers for that, Raymond: always good to know the provenance of things. Presumably, it's not needed in "upcoming" HPE Cray MPICH-s, where later, underlying MPICH-s do the "pick a nic" thing? Kevin M. Buckley -- Supercomputing Systems Administrator Pawsey Supercomputing Centre PERTH Australia