Hi Loris,

On 4/30/24 3:43 PM, Loris Bennett via slurm-users wrote:
Hi Dietmar,

Dietmar Rieder via slurm-users <slurm-users@lists.schedmd.com> writes:

Hi Loris,

On 4/30/24 2:53 PM, Loris Bennett via slurm-users wrote:
Hi Dietmar,
Dietmar Rieder via slurm-users <slurm-users@lists.schedmd.com>
writes:

Hi,

is it possible to have slurm scheduling jobs automatical according to
the "-t" time requirements to a fitting partition?

e.g. 3 partitions

PartitionName=standard Nodes=c-[01-10] Default=YES MaxTime=04:00:00
DefaultTime=00:10:00 State=UP OverSubscribe=NO
PartitionName=medium Nodes=c-[04-08] Default=NO MaxTime=24:00:00
DefaultTime=04:00:00 State=UP OverSubscribe=NO
PartitionName=long Nodes=c-[09-10] Default=NO MaxTime=336:00:00
DefaultTime=24:00:00 State=UP OverSubscribe=NO


So in the standard partition which is the default we have all nodes
and a max time of 4h, in the medium partition we have 4 nodes with a
max time of 24h and in the long partition we have 2 nodes with a max
time of 336h.

I was hoping that if I submit a job with -t 01:00:00 it can be run on
any node (standard partition), whereas when specifying -t 05:00:00 or
-t 48:00:00 the job will run on the nodes of the medium or long
partition respectively.

However, my job will not get scheduled at all when -t is greater than
01:00:00

i.e.

]$ srun --cpus-per-task 1 -t 01:00:01  --pty bash
srun: Requested partition configuration not available now
srun: job 42095 queued and waiting for resources

it will wait forever because the standard partition is selected, I was
thinking that slurm would automatically switch to the medium
partition.

Do I misunderstand something there? Or can this be somehow configured.
You can specify multiple partitions, e.g.
      $ salloc --cpus-per-task=1 --time=01:00:01
--partition=standard,medium,long
Notice that rather than using 'srun ... --pty bash', as far as I
understand, the preferred method is to use 'salloc' as above, and to use
'srun' for starting MPI processes.

Thanks for the hint. This works nicely, but it would be nice that I
would not need to specify the partition at all. Any thoughts?

I am not aware that you can set multiple partition as a default.

Diego suggested a possible way which seems to work after a quick test.


The question is why you actually need partitions with different maximum
runtimes.

we would like to have only a sub set of the nodes in a partition for long running jobs, so that there are enough nodes available for short jobs.

The nodes for the long partition, however are also part of the short partition so they can also be utilized when no long jobs are running.

That's our idea....



In our case, a university cluster with a very wide range of codes and
usage patterns, multiple partitions would probably lead to fragmentation
and wastage of resources due to the job mix not always fitting well to
the various partitions.  Therefore, I am a member of the "as few
partitions as possible" camp and so in our set-up we have as essentially
only one partition with a DefaultTime of 14 days.  We do however let
users set a QOS to gain a priority boost in return for accepting a
shorter run-time and a reduced maximum number of cores.

we didn't look into QOS yet, but this might also a way to go, thanks.

Occasionally people complain about short jobs having to wait in the
queue for too long, but I have generally been successful in solving the
problem by having them estimate their resource requirements better or
bundling their work in ordert to increase the run-time-to-wait-time
ratio.


Dietmar

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