Design and Implementation of the 4.4 BSD Operating System - Part 2
Publisher: AW | 1996 | 276 pages | ISBN: 0132317923 | PDF | 18,7 mb
4.4BSD supports a multitasking environment. Each task or thread of execution is termed a process. The context of a 4.4BSD process consists of user-level state, including the contents of its address space and the run-time environment, and kernel-level state, which includes scheduling parameters, resource controls, and identification information. The context includes everything used by the kernel in providing services for the process. Users can create processes, control the processes' execution, and receive notification when the processes' execution status changes. Every process is assigned a unique value, termed a process identifier (PID). This value is used by the kernel to identify a process when reporting status changes to a user, and by a user when referencing a process in a system call.