Fix Nexus GPU jobs for NERSC/Perlmutter

[aannabe]

Proposed changes

OMP_PROC_BIND and OMP_PLACES environment variables should not be set for GPU jobs. With this change, Nexus GPU jobs are running for me on Perlmutter.

What type(s) of changes does this code introduce?

• Bugfix

Does this introduce a breaking change?

• No

What systems has this change been tested on?

NERSC/Perlmutter (Nexus tests are passing)

Checklist

• Yes. This PR is up to date with current the current state of 'develop'

[prckent]

Approving since it allows jobs to run!

However I suspect we might need to revisit this for effective multithreaded GPU offload. Did the environment variable change come as a recommendation from NERSC or through experimentation?

[aannabe]

The change is inferred from the job script examples given on the NERSC website and through testing. The jobs start but hang when the OMP variables are set.

https://docs.nersc.gov/systems/perlmutter/running-jobs/

[aannabe]

I agree this should be revisited once a more efficient job specification is achieved.

[prckent]

Test this please