Setting the Priority of a Job

 

You can set the priority of an import or analysis job. In the Analysis Management pane when configuring an analysis or on the Options tab when configuring an import, select one of the following priorities:

       Low: A job that is not critical and could be run later than other, more urgent jobs. Touchstone initiates low priority jobs in the order in which they are submitted using the following criteria:

       If and when sufficient capacity is available

       If and when there are no normal, high, or top priority jobs waiting

       If the job has been scheduled to run immediately or when the current date and time is after the scheduled date and time of a scheduled job

       Normal: (Default) A job that is not critical but should run at the next available opportunity. Touchstone initiates normal priority jobs in the order in which they are submitted using the following criteria:

       If and when sufficient capacity is available

       If and when there are no high or top priority jobs waiting

       If the job has been scheduled to run immediately or when the current date and time is after the scheduled date and time of a scheduled job

       High: A critical job that must be initiated as soon as possible. Touchstone initiates high priority jobs in the order in which they are submitted using the following criteria:

       If and when sufficient capacity is available

       If and when there are no top priority jobs waiting

       If the job has been scheduled to run immediately or when the current date and time is after the scheduled date and time of a scheduled job

       Top Priority: A highly critical job that must "skip to the front of the line." Touchstone initiates top priority jobs in the order in which they are submitted using the following criteria:

       If and when sufficient capacity is available

       If the job has been scheduled to run immediately or when the current date and time is after the scheduled date and time of a scheduled job

  Only System Administrators can assign "Top Priority" to a job. For more information about the System Administrator user role, see Role Permissions.

Preemption

The Touchstone job prioritization feature makes use of the default HPC Server 2008 or HPC Server 2012 Scheduler. By default, this Scheduler creates all jobs as "not preemptive." To understand the concept of "preemption," it is important to note that Touchstone jobs often consist of multiple tasks. A preemptive job does not stop or interrupt a task that is currently running as part of another job. Rather, a preemptive higher priority job can start running once a task that is part of another lower priority job completes, thereby releasing some processing capacity. This preemption behavior does not guarantee that the higher priority job will finish first, as lower priority jobs also attempt to use resources whenever possible. Note that preemption does not impact the results of a job.

Consider the following example:

Suppose that preemption is enabled in a Touchstone configuration that includes eight cores. First, you submit a normal priority job that consists of four tasks. The first task of this normal priority job begins running and uses all eight available cores. You then submit a high priority job that consists of three tasks. When the first task within the normal priority job completes, the first task within the high priority job begins running and uses all eight of the available cores. At the same time, the remaining tasks within the normal priority job remain on hold, waiting for additional processing capacity to become available.

When the first task within the high priority job completes, all eight cores become available to process new tasks. Continuing this example, the second task within the high priority job now begins. However, suppose that this second high priority task only requires four cores of processing capacity. In this case, the second task of the normal priority job also starts, using the remaining four available cores. The remaining tasks wait, begin, and complete in the same prioritized manner, holding until sufficient processing capacity is both available and not needed by tasks within higher priority jobs.

 

 

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Touchstone V3.0 Updated December 01, 2016