[slurm-users] random allocation of resources

Benjamin Nacar benjamin_nacar at brown.edu
Wed Dec 1 20:06:51 UTC 2021

Based on some quick experiments, that doesn't do what I'm looking for. I 
set LLN=YES for the default partition and ran my test job several times, 
waiting each time for it to finish before submitting it again (so that 
all compute nodes were idle), and it still ended up on the same (first 
in the file) node every time.

(The documentation is ambiguous on this, but my reading of LLN is that 
it measures "least loaded" according to how many CPUs Slurm itself has 
allocated, not by the actual load average according to "uptime" or some 
other reporting tool. Experiments seem to bear this out - I was watching 
and comparing the load average on the different available compute nodes 
in between running my test jobs.)

~~ bnacar

On 12/1/21 2:18 PM, Guillaume COCHARD wrote:
> Hello,
> I think you are looking for the LLN option (Least Loaded Nodes): https://slurm.schedmd.com/slurm.conf.html#OPT_LLN
> Guillaume
> ----- Mail original -----
> De: "Benjamin Nacar" <benjamin_nacar at brown.edu>
> À: slurm-users at lists.schedmd.com
> Envoyé: Mercredi 1 Décembre 2021 20:07:23
> Objet: [slurm-users] random allocation of resources
> Hi,
> Is there a scheduling option such that, when there are multiple nodes
> that are equivalent in terms of available and allocated resources, Slurm
> would select randomly from among those nodes?
> I've noticed that if no other jobs are running, and I submit a single
> job via srun, with no parameters to specify anything other than the
> defaults, the job *always* runs on the first node in slurm.conf. This
> seems like it would lead to some hosts getting overused and others
> getting underused. I'd like the stress on our hardware to be reasonably
> evenly distributed.
> Thanks,
> ~~ bnacar

Benjamin Nacar
Systems Programmer
Computer Science Department
Brown University

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