[slurm-users] Cgroups and swap with 18.08.1?

[John Hearns]

Rather dumb question from me - you have checked those processes are running
within a cgroup?
I have no experience in constraining the swap usage using cgroups, so sorry
if I am adding nothing to the debate here.

On Tue, 16 Oct 2018 at 04:49, Bill Broadley <bill at cse.ucdavis.edu> wrote:

>
> Greetings,
>
> I'm using ubuntu-18.04 and slurm-18.08.1 compiled from source.
>
> I followed the directions on:
> https://slurm.schedmd.com/cgroups.html
>
> And:
> https://slurm.schedmd.com/cgroup.conf.html
>
> That resulted in:
> $ cat slurm.conf | egrep -i "cgroup|CR_"
> ProctrackType=proctrack/cgroup
> TaskPlugin=task/cgroup
> SelectTypeParameters=CR_CPU_MEMORY
> JobAcctGatherType=jobacct_gather/cgroup
>
> $ cat /etc/default/grub  | grep GRUB_CMDLINE_LINUX=
> GRUB_CMDLINE_LINUX='cgroup_enable=memory swapaccount=1 console=tty0
> transparent_hugepage=madvise console=ttyS0,57600'
>
> $ cat cgroup.conf
> CgroupAutomount=yes
> ConstrainCores=yes
> ConstrainDevices=yes
> ConstrainRAMSpace=yes
> ConstrainSwapSpace=yes
> MaxSwapPercent=0
> AllowedSwapSpace=0
>
> So I expect jobs to not use swap.  Turns out if I run a 3GB ram process
> with
> sbatch --mem=1000 I just get a process that uses 1GB ram and 2GB of swap.
>
> So a 3GB process with --mem=1000:
>   $ ps acux
>   USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
>   bill     17698 11.1  1.5 2817020 1015392 ?     D    20:40   0:13 stream\
>
>   $ smem
>   User     Count     Swap      USS      PSS      RSS
>   bill         1  1795552  1017048  1017076  1018492
>
> With --mem=3000 zero swap is used and the job consumes 100% of a CPU.
>
>
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