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Age= The Value is based on the job pending time (since eligible) normalized against the PriorityMaxAge parameter, currently PriorityMaxAge is set to 7-00:00:00.
JobSize = The job size factor correlates to the number of nodes or CPUs the job has requested, the larger the job, the closer to 1 is the jobsize factor. Currently the contribution from this factor is negligible.
Partition = The value is calculated as the ratio between the priority of the partition requested by the job against the maximum partition priority. Currently the max partition priority is set to 14 (for partition interactive)
QOS = The Quality of Services factor is calculated as the ratio between the job's qos priority and the maximum qos priority. By default each job is submitted with the qos "normal" which has a zero priority value
TRES = not currently active, should always be zero
FairShare =This value is proportional to the ratio of resources available to each users and the amount of resources that has been consumed by the user submitting the job, see below for details.
Each of these factors is then augmented by a custom multiplier in order to obtain the overall JobPriority value accordingly with the formula:
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PriorityWeightAge = 200000
PriorityWeightFairShare = 1000000
PriorityWeightJobSize = 10000
PriorityWeightPartition = 400000
PriorityWeightQOS = 2000000
PriorityWeightTRES = (null)
FairShare Calculation
Each user fairshare is currently calculated as
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F = 2**(-U/(S*d)) |
where:
S is the normalized number of shares made available for each users. In our current setup all users get the same number of raw share
U is the normalized usage. This is calculated as U= Uh / Rh where Uh is the user historical usage subject to the half-life decay and Rh is the total historical usage across the cluster also subject to the half-life decay
Uh and Rh are calculated as
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Currently Usage is calculated as: Allocated_Ncpus*elapsed_seconds+Allocated_Mem_GiB*0.0625*elapsed_seconds+Allocated_NGPUs*5*elapsed_seconds
d is the FairShareDampeningFactor. This is used to reduce the impact of resource consumption on the fairshare value and to account for the ratio of active users against total users. The value is currently set to 10 and it is dynamically changed as needed.
The initial fairshare value (with zero normalized usage) for each user is equal to 1; if a user is consuming exactly his/her share amount of available resources then his/her fairshare value will be 0.5.
It takes approximately 48 hours for a fully depleted fairshare to return from 0 to 1, assuming no additional usage is being accumulated by the user during those ~48 hours.
Two useful commands to see the priority of pending jobs and fairshare are sprio and sshare
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login02:~ sprio -l
JOBID USER PRIORITY AGE FAIRSHARE JOBSIZE PARTITION QOS NICE TRES
6444966 uid13 12489 5000 4061 0 3429 0 0
6445056 uid13 13061 5000 4061 0 4000 0 0
6445068 uid13 10775 5000 4061 0 1714 0 0
6445078 uid13 10204 5000 4061 0 1143 0 0
6445083 uid13 10204 5000 4061 0 1143 0 0
6586939 uid45 6583 4812 57 0 1714 0 0
6586940 uid45 6583 4812 57 0 1714 0 0
6586941 uid45 6583 4812 57 0 1714 0 0
6586942 uid45 6583 4812 57 0 1714 0 0
6586943 uid45 6583 4812 57 0 1714 0 0
6586944 uid45 6583 4812 57 0 1714 0 0
6586945 uid32 6583 4812 57 0 1714 0 0
6586946 uid32 6583 4812 57 0 1714 0 0
6586947 uid32 6583 4812 57 0 1714 0 0
6586948 uid32 6583 4812 57 0 1714 0 0
login02:~ sshare -u $USER -U
Account User RawShares NormShares RawUsage EffectvUsage FairShare
-------------------- ---------- ---------- ----------- ----------- ------------- ----------
rccg rp189 1 0.000787 320 0.000002 0.999832 |
Partition Priority Tiers
The scheduler tries first to dispatch jobs in the partition interactive, then jobs in the partition priority and finally jobs submitted to all remaining partitions. As a consequence interactive and priority jobs will most likely be dispatched first, even if they have a lower overall priority than jobs pending on other partitions (short,medium,long,mpi,etc.).
Backfill scheduling
Low priority jobs might be dispatched before high priority jobs only if doing so does not impact the expected start time of the high priority jobs and if the required resources by the low priority jobs are free and idle.
How to manage priority of your own jobs
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and in this case the total priority of the user is not conserved. However the priority of the jobs across the cluster usually varies by thousands of points, so changing it with small “nice” values should have a negligible impact on the jobs pending time.
There is a limit on the total CPU-hours that can be reserved by a single lab at any given time. This limit was introduced to prevent a single lab from locking down a large portion of the cluster for extended periods of time. This limit will become active only if multiple users in the same lab are allocating a large portion of the O2 cluster resources. This can for example happen if few users have thousands of multi-day or hundreds of multi-week running jobs. When this limit becomes active the remaining pending jobs will display the message AssocGrpCPURunMinute.
Note: The "gpu" partition has additional limits that might trigger the above message, for more details about the "gpu" partition please refer to the "Using O2 GPU resources" wiki page.
Job priority rewards
Many users have been submitting jobs requesting more memory (--mem) and/or run time (-t) than they need. This leads to longer pending times for the submitting users as well as other cluster users.
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If you are running more than a few jobs, please reduce the requested time to an hour or so. Your jobs will probably pend for a shorter time, and help the scheduler run more efficiently.
Note: Reward QOS are not compatible and cannot be added with other custom priority QOS that might have been granted for special situations.