[slurm-users] Memory requirements: seff vs jobstats

[Loris Bennett via slurm-users]

Hi,

For quite a few jobs which run on our system, 'seff' reports higher values for
'Memory Utilized' than 'jobstats' does via 'CPU memory usage' (see below for
example of a job running on a single node).

I was under the impression that 'seff' reports MaxRSS (from 'sacct'), whereas
'jobstats' reports 'Used' (from cgroups), which, as I understand it, is RSS
plus page cache and possibly some kernel memory. Therefore, I would expect
'jobstats' to generally produce *larger* estimates of memory usage. However,
the discrepancies I see seem always to be such that 'jobstats' report *lower*
memory usage.

Any thoughts on this?

Cheers,

Loris

$ seff 25800851
Job ID: 25800851
Cluster: curta
User/Group: foo/agbar
State: COMPLETED (exit code 0)
Nodes: 1
Cores per node: 24
CPU Utilized: 10-09:05:31
CPU Efficiency: 39.05% of 26-13:51:36 core-walltime
Job Wall-clock time: 1-02:34:39
Memory Utilized: 18.12 GB
Memory Efficiency: 28.64% of 63.28 GB (2.64 GB/core)

$ jobstats 25800851

================================================================================
Slurm Job Statistics
================================================================================
Job ID: 25800851
User/Account: foo/agbar
Job Name: foobar
State: COMPLETED
Nodes: 1
CPU Cores: 24
CPU Memory: 64800MB (2.7GB per CPU-core)
QOS/Partition: standard/main
Cluster: curta
Start Time: Mon Jun 8, 2026 at 3:53 PM
Run Time: 1-02:34:39
Time Limit: 5-00:00:00

Overall Utilization
================================================================================
CPU utilization [||||||||||||||||||| 39%]
CPU memory usage [||||| 11%]

Detailed Utilization
================================================================================
CPU utilization per node (CPU time used/run time)
c036.curta.zedat.fu-berlin.de: 10-09:03:12/26-13:51:36 (efficiency=39.0%)

CPU memory usage per node - used/allocated
c036.curta.zedat.fu-berlin.de: 7.1GB/63.3GB (304.3MB/2.6GB per core of 24)
...

--
Dr. Loris Bennett (Herr/Mr)
FUB-IT, Freie Universität Berlin

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