Short Description

These notes are derived from Chapter 3 of the course material based on the textbook Operating Systems Concepts. This chapter introduces the concept of processes, process control blocks (PCBs), process states, and inter-process communication (IPC). It also covers process creation, termination, and the use of system calls such as fork() and exec() for process management.

Process

A process is a program in execution. While a program is a passive entity stored on a disk (e.g., an executable file), a process is an active entity once it is loaded into memory and executed.

Key Properties of a Process:

• Program code (text section)
• Current activity (represented by the program counter, register contents, etc.)
• Process stack (contains temporary data like function parameters and local variables)
• Data section (contains global variables)
• Heap (contains memory dynamically allocated during runtime)

Process Control Block (PCB)

The Process Control Block (PCB) stores all information associated with a process:

1. Process State: Running, waiting, etc.
2. Process ID (PID): A unique identifier for the process.
3. Program Counter: Contains the address of the next instruction to be executed.
4. CPU Registers: All register information used by the process.
5. Memory Management Information: Information about the memory allocated to the process.
6. Scheduling Information: Priorities, pointers to scheduling queues.
7. Accounting Information: Time spent executing, time limits.