LSF Version 7.3 - Platform LSF Configuration Reference

Preemption of backfill jobs
With preemption of backfill jobs enabled (PREEMPT_JOBTYPE=BACKFILL in
lsb.params), LSF maintains the priority of jobs with resource or slot reservations by
preventing lower-priority jobs that preempt backfill jobs from "stealing" resources from jobs
with reservations. Only jobs from queues with a higher priority than queues that define
resource or slot reservations can preempt backfill jobs. For example,
If … Is configured … And a
priority
of …
The behavior is …
queueR With a resource or
slot reservation
80 Jobs in this queue reserve resources. If backfill scheduling is
enabled, backfill jobs with a defined run limit can use the resources.
queueB As a preemptable
backfill queue
50 Jobs in queueB with a defined run limit use job slots reserved by
jobs in queueR.
queueP As a preemptive
queue
75 Jobs in this queue do not necessarily have a run limit. LSF prevents
jobs from this queue from preempting backfill jobs because queueP
has a lower priority than queue R.
To guarantee a minimum run time for interruptible backfill jobs, LSF suspends them upon
preemption. To change this behavior so that LSF terminates interruptible backfill jobs upon
preemption, you must define the parameter TERMINATE_WHEN=PREEMPT in
lsb.queues.
Configuration to modify preemptive scheduling behavior
There are configuration parameters that modify various aspects of preemptive scheduling
behavior, by
•
Modifying the selection of the queue to preempt jobs from
•
Modifying the selection of the job to preempt
•
Modifying preemption of backfill and exclusive jobs
•
Modifying the way job slot limits are calculated
•
Modifying the number of jobs to preempt for a parallel job
•
Modifying the control action applied to preempted jobs
•
Control how many times a job can be preempted
Feature: Preemptive scheduling
Platform LSF Configuration Reference 51