Queue Selection

The grid engine system does not dispatch jobs that request nonspecific queues if the jobs cannot be started immediately. Such jobs are marked as spooled at the sge_qmaster, which tries to reschedule the jobs from time to time. The jobs are dispatched to the next suitable queue that becomes available.

As opposed to spooling jobs, jobs that are submitted to a certain queue by name go directly to the named queue, regardless of whether the jobs can be started or need to be spooled. Therefore, viewing the queues of the grid engine system as computer science batch queues is valid only for jobs requested by name. Jobs submitted with nonspecific requests use the spooling mechanism of sge_qmaster for queueing, thus using a more abstract and flexible queuing concept.

If a job is scheduled and multiple free queues meet its resource requests, the job is usually dispatched to a suitable queue belonging to the least loaded host. By setting the scheduler configuration entry queue_sort_method to seq_no, the cluster administration can change this load-dependent scheme into a fixed order algorithm. The queue configuration entry seq_no defines a precedence among the queues, assigning the highest priority to the queue with the lowest sequence number.