Low cpu load

Description: A significantly low CPU load, i.e., the number of processes and threads waiting for CPU time, can indicate one of the following:

• wrong parallelization settings, defaults, or automatisms in applications for the number of MPI ranks or number of threads
• inefficient parallelization of the code or load imbalance between MPI ranks or threads

Criterion:

• CPU load one-minute average is significantly lower than the number of CPU cores or hardware threads allocated by the job on the node

Works for shared jobs with existing metrics:

• yes, if not the load_one is used but the CPU-core-specific cpu_load_core.

Possible false positives:

• section in the application with less parallelization like IO or stages in the computation

Possible cures/workarounds:

• checking parallelization settings