seff is short for “slurm efficiency” and will display the percentage of CPU and Memory used by a job relative to how long the job ran. The goal is high efficiency so that jobs are not allocating resources they are not using.

Example of seff for an inefficient job

[jeburks2@login02:~]$ seff 11273084
Job ID: 11273084
Cluster: sol
User/Group: jeburks2/grp_rcadmins
State: COMPLETED (exit code 0)
Cores: 1
CPU Utilized: 00:00:59
CPU Efficiency: 12.55% of 00:07:50 core-walltime
Job Wall-clock time: 00:07:50
Memory Utilized: 337.73 MB
Memory Efficiency: 16.85% of 2.00 GB
[jeburks2@login02:~]$ 

This shows the job had a CPU for 7 minutes, but only used the CPU for 59 seconds, resulting in a 12% efficiency, but did use the memory

Example of sef seff for a CPU efficient job

[jeburks2@login02:~]$ seff 11273083
Job ID: 11273083
Cluster: sol
User/Group: jeburks2/grp_rcadmins
State: TIMEOUT (exit code 0)
Nodes: 1
Cores per node: 4
CPU Utilized: 00:59:39
CPU Efficiency: 98.98% of 01:00:16 core—wall time
Job Wall—clock time: 00:15:04
Memory Utilized: 337.73 MB
Memory Efficiency: 4.12% of 8.00 GB

In this example, the job used all four cores it was allocated for 98% of the time the job ran. The core-wall time is calculated by the number of CPU cores * the length of the job. This 15-minute job with 4 CPUs had a core-wall time of 1:00:00. However, the memory efficiency is rather low. This lets us know that if we run this job in the future, we can allocate less memory. This will reduce the impact to our fair share and use the system more efficiently.