Process: Process Table And Process Control Block (PCB):
What is a Process Table? :
The operating system manages and controls the resources by having a table. Tables are important data structures to store information about every process and resources.
This is the reason the operating system maintains memory tables, input output table, and process tables.
The process tables store the ID of every process and corresponding to it, the pointer to its PCB.
What is Process Control Block? :
A process control block is a data structure maintained by the operating system for every process.
***Some Operating System maintain only PCB in that pCB has all entries stored by a process table.***
A PCB keeps all the information needed to keep track of a process:
•1) Process State: Current state of the process i.e, ready, running,or waiting etc.
• 2) Process Privileges : allow/ disallow access to the system resource.
• 3) Process ID: Unique Identification for each of the process in the operating system.
• 4) Pointer: A pointer to parent process.
• 5) Program Counter: Program counter is a pointer to the address of the next instruction to be executed for this process.
• 6) CPU Registers: Various CPU registers where process need to be stored for execution for running state.
• 7) CPU Scheduling Information
• 8) Memory Management Information: Information of page table, memory limit, segment table information information.
• 9) Accounting Information: It includes the amount of CPU used for process execution, time limits, execution ID etc.
• 10) Input Output Status Information: This include list of input output devices allocated to the process.
•The PCB is maintained for a process throughout its lifetime ,And is deleted once the process terminates: