The time a job requires to run should be given in the job control script via the option --timelimit. This should be specified as accurately as possible.

If the value given is too high, then the job will not be able to profit from backfill:

Backfill is the mechanism whereby a lower-priority job can be started before a higher-priority job in such a way that the start of higher-priority job is not delayed.

In the diagram below, assume Job A has just started. Job B, which requires the node currently occupied by Job A plus some additional nodes, will have to wait until Job A has completed. If Job C has a shorter maximum run-time than Job A, Job C will be able to start before Job B, even if Job B has the higher priority and without delaying the start of Job B. In this way, "gaps" in the scheduling plan can be filled and the throughput of the cluster increased.

If the value is too low, then the job will be terminated once its the time limit is reached.

Note that the maximum time limit possible can be limited by the Quality of Service or QOS.