[slurm-users] Longer queuing times for larger jobs

[David Baker]

Hello,

Our SLURM cluster is relatively small. We have 350 standard compute nodes each with 40 cores. The largest job that users  can run on the partition is one requesting 32 nodes. Our cluster is a general university research resource and so there are many different sizes of jobs ranging from single core jobs, that get routed to a serial partition via the job-submit.lua, through to jobs requesting 32 nodes. When we first started the service, 32 node jobs were typically taking in the region of 2 days to schedule -- recently queuing times have started to get out of hand. Our setup is essentially...

PriorityFavorSmall=NO
FairShareDampeningFactor=5
PriorityFlags=ACCRUE_ALWAYS,FAIR_TREE
PriorityType=priority/multifactor
PriorityDecayHalfLife=7-0

PriorityWeightAge=400000
PriorityWeightPartition=1000
PriorityWeightJobSize=500000
PriorityWeightQOS=1000000
PriorityMaxAge=7-0

To try to reduce the queuing times for our bigger jobs should we potentially increase the PriorityWeightJobSize factor in the first instance to bump up the priority of such jobs? Or should we potentially define a set of QOSs which we assign to jobs in our job_submit.lua depending on the size of the job. In other words, let's say there is large QOS that give the largest jobs a higher priority, and also limits how many of those jobs that a single user can submit?

Your advice would be appreciated, please. At the moment these large jobs are not accruing a sufficiently high priority to rise above the other jobs in the cluster.

Best regards,
David
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