Introduction to Python on Cray EX

Presenter: Jean Pourroy (HPE)

Archived materials on LUMI:

• Slides: /appl/local/training/4day-20241028/files/LUMI-4day-20241028-4_01_Introduction_to_Python_on_Cray_EX.pdf

• Recording: /appl/local/training/4day-20241028/recordings/4_01_Introduction_to_Python_on_Cray_EX.mp4

These materials can only be distributed to actual users of LUMI (active user account).

Q&A

1. Why is it recommended to run Python codes not using multi-threading/multi-processing still with srun?

   • not sure I understand the question, srun allows to run on the compute nodes (otherwise you will run on the login nodes if you use salloc)

   • Note also that in a batch job, there is a difference between calling a program with and without srun. Without srun, it runs in the context of the batch job step, which includes, e.g., all hyperthreads on all cores of the first node of the job available to the job, while with srun, the LUMI-default --hint=nomultithread would apply.