Chapter 4Process Management
4.1 Introduction to Process Management
A process is a program in execution. A process must have system resources, such as memory and the underlying CPU. The kernel supports the illusion of concurrent execution of multiple processes by scheduling system resources among the set of processes that are ready to execute. This chapter describes the composition of a process, the method that the system uses to switch between processes, and the scheduling policy that it uses to promote sharing of the CPU. Later chapters study process creation and termination, signal facilities, and process-debugging facilities.
Two months after the developers began the first implementation of the UNIX operating system, there were two processes: ...