About Scheduling

The grid engine system includes the following job-scheduling activities:

• Predispatching decisions. Activities such as eliminating queues because they are full or overloaded, spooling jobs that are currently not eligible for execution, and reserving resources for higher-priority jobs

• Dispatching. Deciding a job's importance with respect to other pending jobs and running jobs, sensing the load on all machines in the cluster, and sending the job to a queue on a machine selected according to configured selection criteria

• Postdispatch monitoring. Adjusting a job's relative importance as it gets resources and as other jobs with their own relative importance enter or leave the system

The grid engine software schedules jobs across a heterogeneous cluster of computers, based on the following criteria:

• The cluster's current load

• The jobs' relative importance

• The hosts' relative performance

• The jobs' resource requirements, for example, CPU, memory, and I/O bandwidth

Decisions about scheduling are based on the strategy for the site and on the instantaneous load characteristics of each computer in the cluster. A site's scheduling strategy is expressed through the grid engine system's configuration parameters. Load characteristics are ascertained by collecting performance data as the system runs.