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.

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:

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.

Fragmentation

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

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.