What Happens in a Scheduler Interval

The Scheduler schedules work in intervals. Between scheduling actions, the grid engine system keeps information about significant events such as the following:

• Job submission

• Job completion

• Job cancellation

• An update of the cluster configuration

• Registration of a new machine in the cluster

When scheduling occurs, the scheduler first does the following:

• Takes into account all significant events

• Sorts jobs and queues according to the administrator's specifications

• Takes into account all the jobs' resource requirements

• Reserves resources for jobs in a forward-looking schedule

Then the grid engine system does the following tasks, as needed:

• Dispatches new jobs

• Suspends running jobs

• Increases or decreases the resources allocated to running jobs

• Maintains the status quo

If share-based scheduling is used, the calculation takes into account the usage that has already occurred for that user or project.

If scheduling is not at least in part share-based, the calculation ranks all the jobs running and waiting to run. The calculation then takes the most important job until the resources in the cluster (CPU, memory, and I/O bandwidth) are used as fully as possible.