Process Management :

What is process management?

Process management is a mechanism in operating system (OS) which involves handling the execution of process

Key Concept:

• Process

• Process State

• PCB

What is process ?

The program in execution is known as process

Or the program in main memory is known as process

• Active entity

What is program ?

The program in secondary memory is known as program

• Passive entity

How many process CPU execute at a time ?

1

What are the data structure used in process management ?

• Stack

• Heap

• Data

• Text

What does stack store ?

Temporary Data

Whar does Heap Store ?

Dynamically allocated data

What does data store ?

Global and Static Variable

What does text store ？

Left thing in the code

What are PCB or Task Block ?

• PCB is generated by OS for every process for execution

• All the things in PCB is related to processes, which helps for execution

• Process Specific

• It terminated as soon as the process terminated/executed.

PCB consits of ?

• Process ID

• Process State

• CPU registers

• Memory I/O

• Program Counter

• I/O

• Accounting

What is process State ?

The state of process can be :

new

ready

running

waiting

terminated

What is new in process state ?

The process is being created

What is ready in process state ?

The process went from sec memory to main memory

What is running in process state ?

The program being executed there

What is waiting in process state ?

The waiting (or blocked) state in a process state occurs when a process is paused because it is waiting for a specific event to happen, such as:

• Input/output (I/O) operations to complete.

• A resource (like a file or memory) to become available.

• A signal from another process.

What is the terminated state ?

The process has being executed

What are schedulers ?

They are the special components which help transfer process from main memory to secondary memory (vice-versa)

• Allocate the process to processor

What are the types of schedulers ?

• Long term schedular

• Short term schedular

• Medium term schedular

What is long term schedular ?

Work : It loads the program from secondary memory to main memory

• State Transition: The process moves from the newly state (in secondary memory) to the ready state (in main memory).

• The process is now ready to be picked by the short-term scheduler for CPU execution.

What is short term schedular ?

The work of short term schedular is to allocate CPU to one of the process from the main memory

a processor can only have one process at a time

Decide which process get the CPU

What is the Short term schedualr ?

CPU scheduler or dispatcher

What is medium term schedular ?

The medium-term scheduler is part of the operating system that temporarily moves processes from main memory (RAM) to secondary storage (disc) to free up space. It brings them back to memory later, when resources are available or the process is ready to run again

• Swapping done by medium-term scheduler

What is the other name of Medium term schedular ?

Swapping / swapper