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
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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 <discuss@mpich.org>
Date: Tuesday, March 10, 2026 at 20:33
To: discuss@mpich.org <discuss@mpich.org>
Cc: Kevin Buckley <kevin.buckley.pawsey.org.au@gmail.com>
Subject: Re: [mpich-discuss] How does MPICH dtermine available NICs?
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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