Operating System Tutorial

What is Operating System Evolution of Operating System Types of Operating System Functions of Operating System What is Kernel and Types of Kernel Operating System Properties Operating System Services Components of Operating System Needs of the Operating System Linux Operating System Unix Operating System Ubuntu Operating System What is DOS Operating System Difference Between Multi-programming and Multitasking What is Thread and Types of Thread Process Management Process State What is Process Scheduler and Process Queue What is Context Switching What is CPU Scheduling Scheduling Algorithm FCFS (First-come-First-Serve) Scheduling SJF (Shortest Job First) Scheduling Round-Robin CPU Scheduling Priority Based Scheduling HRRN (Highest Response Ratio Next) Scheduling Process Synchronization Lock Variable Mechanism TSL Mechanism Turn Variable Mechanism Interested Variable Mechanism What is Producer-Consumer Problem What is Semaphore in Operating System Monitors in Operating System What is Deadlock Deadlock Avoidance Strategies for Handling Deadlock Deadlock Prevention Deadlock Detection and Recovery Resource Allocation Graph Banker’s Algorithm in Operating System Fixed Partitioning and Dynamic Partitioning Partitioning Algorithms What is Paging and Segmentation What is Demand Paging What is Virtual Memory Disk Scheduling Algorithms FCFS and SSTF Disk Scheduling Algorithm SCAN and C-SCAN Disk Scheduling Algorithm Look and C-Look Disk Scheduling Algorithm File in Operating System File Access Methods in Operating System File Allocation Method Directory Structure in Operating System Difference between C-LOOK and C-SCAN Difference between Rotational Latency and Disk Assess Time Trap vs Interrupt How to implement Monitors using Semaphores N-Step-SCAN Disk Scheduling Why is it critical for the Scheduler to distinguish between I/O-bound and CPU-bound programs Difference between C-SCAN and SSTF Difference between SCAN and FCFS Difference between Seek Time and Disk Access Time Difference between SSTF and LOOK

Process Management in OS

A Program will not do anything unless a CPU executes its instructions. An executing program is called a process. The Process requires computer resources to complete its task. More than one process can exist in the system, which needs the same resources at the same time. So, the operating system handles all the resources and processes effectively.

There may be situations where many resources may need to be executed at the same time by one process so that consistency is maintained; otherwise, the system may become inconsistent, and there may be chances of deadlock.  

The operating system performs the following tasks for process management:

  • Suspending and restarting the process.
  • Offering mechanisms for process communication.
  • Offering mechanisms for process synchronization.
  • Process scheduling and threads on the CPU.
  • Create and delete system and user processes.

Process: - A process is defined as a program in execution.

Types of Processes

There are two types of Processes:

  1. I/O-Bound Process
  2. CPU-Bound Process
  1. I/O-Bound Process: - It is a type of process in which the process execution time is calculated with the help of the amount of time a process spends to complete the input/output operations.
  2. CPU-Bound Process: - CPU-Bound Process is another type of process in which the process execution time is calculated with the help of the CPU speed. If we use a faster processor, then the CPU-Bound Process may execute faster.

Components of Process

There are four components of the process:

  1. Text
  2. Data
  3. Stack
  4. Heap
Process Management
  1. Text: - Text consists of the value of the program counter and the processor’s registers content that is represented by the current activity.
  2. Data: - Data contains both static as well as global variables.
  3. Stack: - Stack contains temporary data like local variables, return addresses, and method/function.
  4. Heap: - Heap is a dynamic memory which is allocated during the run time of a process.

Attributes of Process

The attributes of a process are also called the context of the process. These attributes design the Process Control Block (PCB).

The attributes used to store Process Control Block (PCB) are:

  1. Process ID
  2. Program Counter
  3. Process State
  4. Priority
  5. General Purpose Registers
  6. List of open Files
  7. List of open Devices
Process Management

Process ID: - Process ID is a unique ID that is assigned to the process at that time when the process was created.

Program counter: - The Program counter holds the address of the last instruction of the process.

Process State: - The process state may be one of the following states, i.e., running, ready, waiting, terminate, etc.

Priority: - Some priority is assigned to every process in the memory. The process that has the highest priority between the processes gets the CPU first.

General Purpose Registers: - These registers are used to store the data which is generated at the time of process execution.

List of Open Files: - A list of open files contains some files that require to be present in the main memory when the process is executing

List of Open Devices: - List of open devices contains the list of devices that are used when the process is executing.