Process Concept and Management

Introduction :

There are many processes of operating system and for each process you need to control it, so all information takes you to know states of process and how you can manage it

Contents

• What is a Process?
• Process Management
• Process States
• Process Control Block (PCB)

What is a Process?

 

A process is a sequential program in execution. The components of a process are the following:

• The object program to be executed ( called the program text in UNIX)
• The data on which the program will execute (obtained from a file or interactively from the process's user)
• Resources required by the program ( for example, files containing requisite information)
• The status of the process's execution

 

Process Management :

Multiprogramming systems explicitly allow multiple processes to exist at any given time, where only one is using the CPU at any given moment, while the remaining processes are performing I/O or are waiting. 


The process manager is of the four major parts of the operating system. It implements the process abstraction. It does this by creating a model for the way the process uses CPU and any system resources. Much of the complexity of the operating system stems from the need for multiple processes to share the hardware at the same time. As a consequence of this goal, the process manager implements CPU sharing ( called scheduling ), process synchronization mechanisms, and a deadlock strategy. In addition, the process manager implements part of the operating system's protection and security.

Process States

During the lifespan of a process, its execution status may be in one of four states: (associated with each state is usually a queue on which the process resides) 


• Executing: the process is currently running and has control of a CPU
• Waiting: the process is currently able to run, but must wait until a CPU becomes available
• Blocked: the process is currently waiting on I/O, either for input to arrive or output to be sent
• Suspended: the process is currently able to run, but for some reason the OS has not placed the process on the ready queue
• Ready: the process is in memory, will execute given CPU time.

Process Control Block (PCB) 

If the OS supports multiprogramming, then it needs to keep track of all the processes. For each process, its process control block PCB is used to track the process's execution status, including the following: 

- Its current processor registers contents

- Its processor state (if it is blocked or ready)

- Its memory state 

- A pointer to its stack

- Which resources have been allocated to it

       - Which resources it needs

 This video learn you relation between process and management.

 

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