Ticket 13950 - fix rss in sacct to include tmpfs and match memcg behaviour
Summary: fix rss in sacct to include tmpfs and match memcg behaviour
Status: RESOLVED WONTFIX
Alias: None
Product: Slurm
Classification: Unclassified
Component: Accounting (show other tickets)
Version: 21.08.7
Hardware: Linux Linux
: C - Contributions
Assignee: Felip Moll
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Reported: 2022-04-28 00:49 MDT by Robin Humble
Modified: 2025-09-22 05:55 MDT (History)
2 users (show)

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Attachments
make accounting rss include tmpfs usage to match memcg behaviour (3.17 KB, patch)
2022-04-28 00:49 MDT, Robin Humble 		Details | Diff
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Description Robin Humble 2022-04-28 00:49:31 MDT 
Created attachment 24712 [details]
make accounting rss include tmpfs usage to match memcg behaviour

Hi,

we've been using a patch to fix rss in sacct from memcg for a few years.

the issue is that the kernel's memcg includes rss+tmpfs in its OOM decision making, but rss in sacct doesn't include tmpfs, so they don't always line up.

if jobs use a lot of shared mem or write plain files to /dev/shm, then jobs can be killed by OOM, but rss in sacct is wrong so it's confusing why the job was killed.

here's a patch to fix it.

TBH I kinda thought I'd submitted this patch a few years ago. hopefully this isn't a dup.

cheers,
robin
Comment 3 Felip Moll 2025-09-22 05:55:59 MDT 
(In reply to Robin Humble from comment #0)
> Created attachment 24712 [details]
> make accounting rss include tmpfs usage to match memcg behaviour
> 
> Hi,
> 
> we've been using a patch to fix rss in sacct from memcg for a few years.
> 
> the issue is that the kernel's memcg includes rss+tmpfs in its OOM decision
> making, but rss in sacct doesn't include tmpfs, so they don't always line up.
> 
> if jobs use a lot of shared mem or write plain files to /dev/shm, then jobs
> can be killed by OOM, but rss in sacct is wrong so it's confusing why the
> job was killed.
> 
> here's a patch to fix it.
> 
> TBH I kinda thought I'd submitted this patch a few years ago. hopefully this
> isn't a dup.
> 
> cheers,
> robin

Hello Robin, thank you for your contribution.

Unfortunately we are not going to add behavioral changes to cgroup/v1 as we freezed its development in favor of cgroup/v2.

I understand your concerns and actually in cgroup/v2 the memory is accounted based on memory.current, which includes the shmem, so accounting should be now what you expect.

I hope you understand. I am closing this issue now.

Thanks again