Frame Scheduler Basics

Frame Scheduler Basics

A Frame Scheduler takes over the scheduling and dispatching of processes on one CPU. It isolates the CPU (see "Isolating a CPU From TLB Interrupts"), and completely supersedes the operation of the normal IRIX scheduler on that CPU. Only processes enqueued to the Frame Scheduler can use the CPU. IRIX dispatching priorities are not relevant on that CPU. If that CPU is assigned to a processor set (see "Using Processor Sets"), the set assignment is ignored while the Frame Scheduler is running.

The execution of normal processes, daemons, and pending timeouts are all migrated to other CPUs--typically to CPU 0, which cannot be owned by a Frame Scheduler. All interrupt handling is usually directed away from a Frame Scheduler CPU as well (see "Preparing the System"). However, a Frame Scheduler CPU can be used to handle interrupts, although doing so runs a risk of causing overruns.