What is Process Control Block ?

Today in thiComputer Science Study Material for Gate we will discuss about process control block and its various field which provides the information about process. .So let see what is process control block.

A Process Control Block is a data structure maintained by the Operating System for every process. Each process has it own data structure.  When a process is created then a unique id is assigned to the process Operating system identify a process among all processes on the basis of this process id. A PCB keeps all the information needed to keep track of a process. Generally a process control block contains the following information about a process. 

All the fields of a process control block are as shown in Figure 1.

operating system study material

Process State: Process state field of process control block tell about the current state of the process. These states may be ready , running and waiting.

Process Privileges: This is required to provide the information about allow/disallow access the  system resources.

Process ID: Every Process has a Unique identification for each of the processes in the operating system.

Pointer: The pointer  field of process control block represent a pointer to the parent process.

Program Counter: Program Counter is a pointer to the address of the next instruction to be executed for this process.

CPU Registers: Various CPU registers where processes need to be stored for execution for running state.

CPU Scheduling Information: Process priority and other scheduling information which is required to schedule the process.

Memory Management Information: This includes the information of page table, memory limits, and segment table, depending on the memory used by the operating system.

Accounting Information: This includes the amount of CPU used for process execution, time limits, execution ID, and so on.

IO Status Information: This includes a list of I/O devices allocated to the process.

I hope that this Operating System Tutorial on process control block will be beneficial for computer science student.

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