Platform LSF Administration Guide Version 6.2

About Preemptive Scheduling
Administering Platform LSF
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About Preemptive Scheduling
Preemptive scheduling lets a pending high-priority job take job slots away from a
running job of lower priority. When two jobs compete for the same job slots, LSF
automatically suspends the low-priority job to make slots available to the high-priority
job. The low-priority job is resumed as soon as possible.
Use preemptive scheduling if you have long-running low-priority jobs causing high-
priority jobs to wait an unacceptably long time.
Limitation
The following types of jobs cannot be preempted:
◆ Jobs that have been forced to run with the command brun
◆ NQS jobs
◆ Backfill jobs
◆ Exclusive jobs
Preemptive and preemptable queues
Preemptive
queues
Jobs in a preemptive queue can preempt jobs in any queue of lower priority, even if the
low-priority queues are not specified as preemptable.
Preemptable
queues
Jobs in a preemptable queue can be preempted by jobs from any queue of a higher
priority, even if the high-priority queues are not specified as preemptive.
Preemptive and preemptable jobs
Preemptive jobs
Preemptive jobs are pending in a high-priority queue and require the specified job slots.
Their queue must be able to preempt the low-priority queue.
Preemptable jobs
Preemptable jobs are running in a low-priority queue and are holding the specified job
slot. Their queue must be able to be preempted by the high-priority queue.