Skip to content

Running Applications

Presenter: Harvey Richardson (HPE)

Archived materials on LUMI:

  • Slides: /appl/local/training/4day-20240423/files/LUMI-4day-20240423-1_03_Running_Applications.pdf

  • Recording: /appl/local/training/4day-20240423/recordings/1_03_Running_Applications.mp4

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

Q&A

  1. Can you clarify the differences between: ntasks-per-core vs ntasks-per-node and ntasks in SLURM terminology?

    • -ntasks is the total number of MPI ranks, -ntasks-per-node is the number of MPI ranks per each node, e.g. I want to run 128 MPI ranks with 4 ranks per each node (i.e. 32 nodes), so I can use: --ntasks=128 --ntasks-per-node=4. The -ntasks-per-core is only relevant if you want to use hyperthreads. You can find more info with man srun.

  2. What does $SBATCH --exclusive do? is it quite mandatory to include it in my bash script when executing sbatch job?

    • exclusive is set for some queues, so you will get the entire node even if you are asking for less resources (you can use scontrol show partition standard, where standard is the queue, and check for the "EXCLUSIVE"). And you can use it in the other partitions (e.g., small and small-g) to get exclusive access to that node (and of course be billed for exclusive acces). But a node in small or small-g will still not be fully equivalent to a node in standard or standard-g, as some defaults, e.g., for memory, are set differently.