Operating System Tutorial

Operating System Tutorial Types of Operating System Evolution of Operating System Functions of Operating System Operating System Properties Operating System Services Components of Operating System Needs of the Operating System

Operating Systems

Linux Operating System Unix Operating System Ubuntu Operating System Chrome Operating Systems Fedora Operating System MAC Operating System MS Windows Operating System Solaris Operating System Cooperative Operating System CorelDRAW Operating System CentOS FreeBSD Operating Systems Batch Operating System MS-DOS Operating System Commercial Mobile Operating Systems


Difference Between Multi-programming and Multitasking Difference between C-LOOK and C-SCAN Difference between Rotational Latency and Disk Assess Time Trap vs Interrupt Difference between C-SCAN and SSTF Difference between SCAN and FCFS Difference between Seek Time and Disk Access Time Difference between SSTF and LOOK Difference between Process and Program in the Operating System Difference between Protection and Security in Operating System

How To

How to implement Monitors using Semaphores How to Install a Different Operating System on a PC


What is Kernel and Types of Kernel What is DOS Operating System What is Thread and Types of Thread What is Process Scheduler and Process Queue What is Context Switching What is CPU Scheduling What is Producer-Consumer Problem What is Semaphore in Operating System Monitors in Operating System What is Deadlock What is Paging and Segmentation What is Demand Paging What is Virtual Memory What is a Long term Scheduler What is Page Replacement in Operating System What is BSR Mode What is Convoy Effect What is Job Sequencing in Operating System Why is it critical for the Scheduler to distinguish between I/O-bound and CPU-bound programs Why is there a Need for an Operating System


Process Management Process State 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 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 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 N-Step-SCAN Disk Scheduling Feedback Queue in Operating System Contiguous Memory Allocation in Operating System Real-time Operating System Starvation in Operating System Thrashing in Operating System 5 Goals of Operating System Advantages of Operating System Advantages of UNIX Operating System Bit Vector in Operating System Booting Process in Operating System Can a Computer Run Without the Operating System Dining Philosophers Problem in Operating System Free Space Management in Operating System Inter Process Communication in Operating System Swapping in Operating System Memory Management in Operating System Multiprogramming Operating System Multitasking Operating Systems Multi-user Operating Systems Non-Contiguous Memory Allocation in Operating System Page Table in Operating System Process Scheduling in Operating System Segmentation in Operating System Simple Structure in Operating System Single-User Operating System Two Phase Locking Protocol Advantages and Disadvantages of Operating System Arithmetic operations in binary number system Assemblers in the operating system Bakery Algorithm in Operating System Benefits of Ubuntu Operating System CPU Scheduling Criteria in Operating System Critical Section in Operating System Device Management in Operating System Linux Scheduler in Operating System Long Term Scheduler in Operating System Mutex in Operating System Operating System Failure Peterson's Solution in Operating System Privileged and Non-Privileged Instructions in Operating System Swapping in Operating System Types of Operating System Zombie and Orphan Process in Operating System 62-bit operating system Advantages and Disadvantages of Batch Operating System Boot Block and Bad Block in Operating System Contiguous and Non - Contiguous Memory Allocation in Operating System Control and Distribution Systems in Operations Management Control Program in Operating System Convergent Technologies in Operating System Convoy Effect in Operating System Copy Operating Systems to SSD Core Components of Operating System Core of UNIX Operating System Correct Value to return to the Operating System Corrupted Operating System Cos is Smart Card Operating System Cosmos Operating Systems Examples Generation of Operating System Hardware Solution in Operating System Process Control Block in Operating System Function of Kernel in Operating System Operating System Layers History of Debian Operating Systems Branches and Architecture of Debian Operating Systems Features and Packages of Debian Operating Systems Installation of Operating System on a New PC Organizational Structure and Development in Debian Operating Systems User Interface in Operating System Types Of Memory in OS Operating System in Nokia Multilevel Paging in OS Memory Mapping Techniques in OS Memory Layout of a Process in Operating System Hardware Protection in Operating System Functions of File Management in Operating System Core of Linux Operating System Cache Replacement Policy in Operating System Cache Line and Cache Size in Operating System What is Memory Mapping? Difference Between Network Operating System And Distributed Operating System What is the difference between a Hard link and a Soft Link? Principles of Preemptive Scheduling Process Scheduling Algorithms What is NOS? What is the Interrupt I/O Process? What is Time Sharing OS What is process termination? What is Time-Sharing Operating System What is Batch File File system manipulation What is Message-passing Technique in OS Logical Clock in Distributed System

Memory Management in Operating System

The term "Main Memory" refers to the computer's internal physical memory. It is distinguished from external mass storage devices like disk drives by using the term "main." RAM is another name for the main memory. The computer can only alter data in the main memory. As a result, the system's main memory must be dragged from a memory device for each program and file we run.

In order to run the programs, the main memory is loaded with them all. This mechanism is known as Dynamic Loading, and it improves performance by packing intact software into memory, but only rarely a crucial routine or part of the program is loaded into most of the memory.

Additionally, a program may depend on another program at times. When necessary, the CPU links the dependent programs to the most actively running program rather than loading all of them. This component is perceived as Dynamic Linking.

Memory Management in OS

What is Memory Management in Operating System?

Memory management is the process of coordinating and controlling a computer's memory. Blocks assign portions to various running programs to improve the system's overall performance. This method makes it easier to keep track of every memory location, regardless of whether it has been allocated to a process or is free.

This method decides when and which processes will receive memory. It likewise keeps the count of how much memory can be dispensed to a process. Because it keeps track of everything, any time memory is freed or unallocated, the status changes accordingly.

Memory management is a component of this activity that takes into account the memory device's capacity limitations by allocating memory space when it is no longer required or extending that space through virtual memory. Memory management aims to reduce memory usage so that the central processing unit (CPU) can quickly access the data and instructions it needs to carry out the various processes.

Methods for Memory Management

There are a variety of methods for memory management. The Operating System can use these methods to intelligently manage memory:

Memory Management in OS

Swapping in OS

In order to run the OS, a process needs to be in memory. However, there are times when a timesharing system's main memory is insufficient to accommodate all of the currently running processes. As a result, the extra process is brought in to run dynamically and stored on disk. The process of bringing each process in main memory, running it for some time, and then putting it back on the disk is known as swapping.

Contiguous Memory Allocation

In contiguous memory allocation, each process occupies a single, contiguous block of memory. Memory is divided into several partitions of the same size. One process is contained in each partition. A process from the input queue is selected and loaded into a free partition. Holes are the memory's unoccupied blocks. The best hole to allocate is searched through the set of holes.

Memory Protection

Memory protection is the process by which memory access rights on a computer can be controlled. Its primary objective is to prevent a process from accessing unallocated memory. After that it prevents a bug in a process from affecting other processes or the operating system as a whole, resulting in the sending of a segmentation fault or storage violation exception to the troublesome process and, typically, its termination.


In a dynamic memory allocation system, fragmentation occurs when the majority of the free blocks are insufficient to fulfill any request. The inability to utilize the available memory is the most common name for it.

Processes are loaded into and out of memory in such a scenario. As a consequence of this, free holes are present in order to fulfill a request, but they are non-contiguous, or the memory is divided into large number of tiny cracks. This peculiarity is known as Outer Discontinuity.

Additionally, memory is allocated in terms of block sizes whenever the physical memory is divided into fixed-size blocks. It is possible that the requested memory is slightly larger than the space-allocated memory. Internal fragmentation refers to the memory that is internal to a partition but is of no use the difference between allocated and required memory.


Paging is one method for dealing with the fragmentation issue. Paging is a memory management technique that prevents a process's physical address space from spreading. Physical memory is here divided into Pages, equal-sized blocks. The pages of a particular process are loaded into memory frames that are available.

Page Table

A Page Table is the information structure involved by a virtual memory framework in a PC working framework to store the planning between the virtual location and actual addresses.

The CPU is responsible for creating the virtual address, which is also referred to as the logical address. While the actual memory address is known as the physical address.

Segmentation in OS

Another memory management method that allows users to view memory is OS Segmentation. Segmentation makes it possible to divide a single process's virtual address space into segments that can be stored in physical memory in non-contiguous locations.