Job priority behavior

Fair share

The default user-based fair share can be a factor in APS calculation by adding the FS factor to APS_PRIORITY in the queue.

  • APS cannot be used together with DISPATCH_ORDER=QUEUE.
  • APS cannot be used together with cross-queue fair share (FAIRSHARE_QUEUES). The QUEUE_GROUP parameter replaces FAIRSHARE_QUEUES, which is obsolete in LSF 7.0.
  • APS cannot be used together with queue-level fair share or host-partition fair share.

FCFS (first come first serve)

APS overrides the job sort result of FCFS.

SLA scheduling

APS cannot be used together with time-based SLAs with velocity, decline, or throughput goals.

Job re-queuing

All requeued jobs are treated as newly submitted jobs for APS calculation. The job priority, system, and ADMIN APS factors are reset on re-queue.

Rerun jobs

Rerun jobs are not treated the same as requeued jobs. A job typically reruns because the host failed, not through some user action (like job re-queue), so the job priority is not reset for rerun jobs.

Job migration

Suspended (bstop) jobs and migrated jobs (bmig) are always scheduled before pending jobs. For migrated jobs, LSF keeps the existing job priority information.

If LSB_REQUEUE_TO_BOTTOM and LSB_MIG2PEND are configured in lsf.conf, the migrated jobs keep their APS information. When LSB_REQUEUE_TO_BOTTOM and LSB_MIG2PEND are configured, the migrated jobs need to compete with other pending jobs based on the APS value. If you want to reset the APS value, then you should use brequeue, not bmig.

Resource reservation

The resource reservation is based on queue policies. The APS value does not affect current resource reservation policy.

Preemption

The preemption is based on queue policies. The APS value does not affect the current preemption policy.

Chunk jobs

The first chunk job to be dispatched is picked based on the APS priority. Other jobs in the chunk are picked based on the APS priority and the default chunk job scheduling policies.

The following job properties must be the same for all chunk jobs:
  • Submitting user
  • Resource requirements
  • Host requirements
  • Queue or application profile
  • Job priority

Backfill scheduling

Not affected.

Advance reservation

Not affected.

Resizable jobs

For new resizable job allocation requests, the resizable job inherits the APS value from the original job. The subsequent calculations use factors as follows:
Factor or sub-factor Behavior
FAIRSHARE Resizable jobs submitting into fair share queues or host partitions are subject to fair share scheduling policies. The dynamic priority of the user who submitted the job is the most important criterion. LSF treats pending resize allocation requests as a regular job and enforces the fair share user priority policy to schedule them.
The dynamic priority of users depends on:
  • Their share assignment
  • The slots their jobs are currently consuming
  • The resources their jobs consumed in the past
  • The adjustment made by the fair share plug-in (libfairshareadjust.*)

Resizable job allocation changes affect the user priority calculation if RUN_JOB_FACTOR is greater than zero (0). Resize add requests increase number of slots in use and decrease user priority. Resize release requests decrease number of slots in use, and increase user priority. The faster a resizable job grows, the lower the user priority is, the less likely a pending allocation request can get more slots.

MEM Use the value inherited from the original job
PROC Use the MAX value of the resize request
SWAP Use the value inherited from the original job
JPRIORITY Use the value inherited from the original job. If the automatic job priority escalation is configured, the dynamic value is calculated.

For a requeued and rerun resizable jobs, the JPRIORITY is reset, and the new APS value is calculated with the new JPRIORITY.

For migrated resizable job, the JPRIORITY is carried forward, and the new APS value is calculated with the JPRIORITY continued from the original value.
QPRIORITY Use the value inherited from the original job
ADMIN Use the value inherited from the original job