Process Control Block

A process control block (PCB) stores data about the process, such as registers, quantum, priority, and so on. The process table refers to an array of PCBs, which means that it logically contains a PCB for each of the system’s active processes.

In this article, we will dive deeper into the Process Control Block according to the GATE Syllabus for (Computer Science Engineering) CSE. Let us read ahead to learn more.

Table of Contents

What is the Process Control Block?
Process Attributes
Process Id
Program Counter
Process State
Priority
General Purpose Registers
List of Open Files
List of Open Devices
Important Notes

What is the Process Control Block?

A Process Control Block (PCB) refers to a data structure that keeps track of information about a specific process. The CPU requires this information to complete the job.

A process’s Process Control Block looks like this:

process-control-block

Each process has its own PCB (process control block) that identifies it.

It is also referred to as the context of the process.

Process Attributes

Here are the various attributes of any process that is stored in the PCB:

Process Id

The process Id is a one-of-a-kind identifier for each system process. Each process is given a unique identifier when it is created.

Program Counter

The address of the next instruction to be executed is specified by the program counter. The address of the program’s first instruction is used to initialize the program counter before it is executed.

The value of the program counter is incremented automatically to refer to the next instruction when each instruction is executed. This process continues till the program ends.

Process State

Throughout its existence, each process goes through various phases. The present state of the process is defined by the process state.

Priority

The priority of a process determines how important it is to complete it.

Among all the processes, the one with the greatest priority receives the most CPU time.

General Purpose Registers

General-purpose registers are used to store data created during the execution of a task. Each and every process consists of its own set of registers, which its PCB keeps track of.

List of Open Files

Each process necessitates the presence of certain files in the main memory during execution. During the process’s execution, PCB keeps track of the files it uses.

List of Open Devices

During the procedure’s execution, PCB keeps track of all open devices.

Important Notes

Each process’s PCB is stored in the main memory.
Each process has only one PCB associated with it.
All of the processes’ PCBs are listed in a linked list.

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