[Beowulf] head node abuse

Joe Landman joe.landman at gmail.com
Fri Mar 26 14:21:38 UTC 2021

Near term, could you make sure their groups are covered in 
/etc/security/limits.conf  ?

Something like

     @users    soft    cpu    5 # 5 min of cpu time

     @users    hard    cpu    10 # 5 min of cpu time


Way ... way back when I helped others do this stuff, I set up isolated 
login VMs.  Everyone got their own.  I could limit them to 1 core, 4GB 
ram, and they had queue access (this was in the PBS days).  I lit up 
like 20 of these small VMs per "login node", each with their own IP.  
The VMs could idle fairly nicely.  We could rate limit their (virtual) 
networks using tc, and throttle their disk IO.

Haven't done that in a while.  These days, you might look at login 
containers for the same thing.  Just set up limits on the memory/network 
/cpu for those and off to the races you go (SMOP :D )

On 3/26/21 9:56 AM, Michael Di Domenico wrote:
> does anyone have a recipe for limiting the damage people can do on
> login nodes on rhel7.  i want to limit the allocatable cpu/mem per
> user to some low value.  that way if someone kicks off a program but
> forgets to 'srun' it first, they get bound to a single core and don't
> bump anyone else.
> i've been poking around the net, but i can't find a solution, i don't
> understand what's being recommended, and/or i'm implementing the
> suggestions wrong.  i haven't been able to get them working.  the most
> succinct answer i found is that per user cgroup controls have been
> implemented in systemd v239/240, but since rhel7 is still on v219
> that's not going to help.  i also found some wonkiness that runs a
> program after a user logs in and hacks at the cgroup files directly,
> but i couldn't get that to work.
> supposedly you can override the user-{UID}.slice unit file and jam in
> the cgroup restrictions, but I have hundreds of users clearly that's
> not maintainable
> i'm sure others have already been down this road.  any suggestions?
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Joe Landman
e: joe.landman at gmail.com
t: @hpcjoe
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g: https://github.com/joelandman
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