[slurm-users] random allocation of resources

[Brian Andrus]

That would make sense, as slurm would not be aware of anything else. 
Slurmd does not report any ongoing status of resources. It is slurmctld 
that keeps track of what it has allocated.

If you truly want something like this, you could have a wrapper script 
look at available nodes, pick a random one and set the job to use that node.

Brian Andrus


On 12/1/2021 12:06 PM, Benjamin Nacar wrote:
> 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
>>
>