Once a process controls the CPU, its instructions will be executed until its allotted time expires, or until it terminates, or until it requests an input or output operation. The operating system must then determine when the CPU can be made available to the process, and for how long. The operating system must ensure that each process gets a fair share of the CPU's time.īefore a program can be executed, at least part of the program's executable code must be loaded into memory as a process.

In a multiprogramming system, there will be a number of competing processes. The term process refers here to program code that has been loaded into a computer's memory so that it can be executed by the central processing unit (CPU). The four main operating system management functions (each of which will be dealt with in greater depth elsewhere) are: Each of these management functions is briefly described below in order to provide an overall context for what follows.

Although the range of services and value-added features provided by a modern operating system is continually growing, there are four fundamental operating system management functions that are implemented by all operating systems.

Disk management in operating system