Embedded RTOS Design

2

Multitasking and scheduling

Abstract

Tasks, threads, and processes are defined in this chapter, along with the descriptions of a variety of types of task scheduler. The context switch is described in detail and the role of interrupts is considered.

Keywords

RTOS; nucleus; task; thread; process; scheduler; context switch

We have already considered the multitasking concept—multiple quasi-independent programs apparently running at the same time, under the control of an operating system. Before we look at tasks in more detail, we need to straighten out some more terminologies.

Tasks, threads, and processes

We use the word “task”—and I will continue to do so—but it does not have a very precise meaning. Two other terms—“thread” and “process”—are more specific ...