Administering Platform LSF - SAS

Optimized Preemption of Parallel Jobs
Optimized Preemption of Parallel Jobs
You can configure preemption for parallel jobs to reduce the number of jobs
suspended in order to run a large parallel job.
When a high-priority parallel job preempts multiple low-priority parallel jobs,
sometimes LSF preempts more low-priority jobs than are necessary to release
sufficient job slots to start the high-priority job.
The PREEMPT_FOR parameter in lsb.params with the MINI_JOB keyword
enables the optimized preemption of parallel jobs, so LSF preempts fewer of
the low-priority parallel jobs.
Enabling the feature only improves the efficiency in cases where both
preemptive and preempted jobs are parallel jobs.
How optimized preemption works
When you run many parallel jobs in your cluster, and parallel jobs preempt
other parallel jobs, you can enable a feature to optimize the preemption
mechanism among parallel jobs.
By default, LSF can over-preempt parallel jobs. When a high-priority parallel
job preempts multiple low-priority parallel jobs, sometimes LSF preempts more
low-priority jobs than are necessary to release sufficient job slots to start the
high-priority job. The optimized preemption mechanism reduces the number
of jobs that are preempted.
Enabling the feature only improves the efficiency in cases where both
preemptive and preempted jobs are parallel jobs. Enabling or disabling this
feature has no effect on the scheduling of jobs that require only a single
processor.
Configuring optimized preemption
Use the PREEMPT_FOR parameter in lsb.params and specify the keyword
MINI_JOB to configure optimized preemption at the cluster level.
If the parameter is already set, the MINI_JOB keyword can be used along with
other keywords; the other keywords do not enable or disable the optimized
preemption mechanism.
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Administering Platform LSF