5.2 Real-time scheduling

Recall from section 1.7.2 that a scheduler determines the order in which tasks are executed by processors available to the real-time system. As is illustrated in figure 5.2, tasks that are given to the scheduler from active programs are called active or ready tasks. The scheduler uses a scheduling algorithm to determine a processor's schedule, a sequence of tasks stored as a queue. The schedule must be updated whenever a new task becomes active or a task is dispatched from the queue to the processor. A task being processed is said to be running or executing.

There are two types of events that can suspend a running task. The first is an interrupt, which arises from a source …