LSF Version 7.3 - Administering Platform LSF

Absolute Job Priority Scheduling
458 Administering Platform LSF
When configured in a queue, APS sorts pending jobs for dispatch according to a job
priority value calculated based on several configurable job-related factors. Each job
priority weighting factor can contain subfactors. Factors and subfactors can be
independently assigned a weight.
APS provides administrators with detailed yet straightforward control of the job
selection process.
◆ APS only sorts the jobs; job scheduling is still based on configured LSF
scheduling policies. LSF attempts to schedule and dispatch jobs based on their
order in the APS queue, but the dispatch order is not guaranteed.
◆ The job priority is calculated for pending jobs across multiple queues based on
the sum of configurable factor values. Jobs are then ordered based on the
calculated APS value.
◆ You can adjust the following for APS factors:
❖ A weight for scaling each job-related factor and subfactor
❖ Limits for each job-related factor and subfactor
❖ A grace period for each factor and subfactor
◆ To configure absolute priority scheduling (APS) across multiple queues, define
APS queue groups. When you submit a job to any queue in a group, the job's
dispatch priority is calculated using the formula defined in the group's master
queue.
◆ Administrators can also set a static system APS value for a job. A job with a
system APS priority is guaranteed to have a higher priority than any calculated
value. Jobs with higher system APS settings have priority over jobs with lower
system APS settings.
◆ Administrators can use the ADMIN factor to manually adjust the calculated
APS value for individual jobs.
Scheduling priority factors
To calculate the job priority, APS divides job-related information into several
categories. Each category becomes a factor in the calculation of the scheduling
priority. You can configure the weight, limit, and grace period of each factor to get
the desired job dispatch order.
LSF sums the value of each factor based on the weight of each factor.
Factor weight The weight of a factor expresses the importance of the factor in the absolute
scheduling priority. The factor weight is multiplied by the value of the factor to
change the factor value. A positive weight increases the importance of the factor,
and a negative weight decreases the importance of a factor. Undefined factors have
a weight of 0, which causes the factor to be ignored in the APS calculation.
Factor limit The limit of a factor sets the minimum and maximum absolute value of each
weighted factor. Factor limits must be positive values.
Factor grace period Each factor can be configured with a grace period. The factor only counted as part
of the APS value when the job has been pending for a long time and it exceeds the
grace period.