|What do you mean by memory management? Memory is the important part of the computer that is used to store the data. Its management is critical to the computer system because the amount of main memory available in a computer system is very limited. At any time, many processes are competing for it. Moreover, memory management in os, to increase performance, several processes are executed simultaneously.

For this, memory management in os, we must keep several processes in the main memory, memory management in os, so it is even more important to manage them effectively. Role of Memory management Following are the important roles of memory management in a computer system: Memory manager is used to memory track of the status of memory locations, whether it is free or allocated. It addresses primary memory by providing abstractions so that memory perceives a large memory is allocated to it.

Memory management permits computers with a small amount of main memory to execute programs larger than the size or amount of available memory. It does this by moving information management and forth memory primary memory and secondary memory by using the concept of swapping.

The memory manager is responsible for protecting the management allocated to each process from being corrupted by another process. If this is not ensured, then the system may exhibit unpredictable behavior.

Memory managers should enable sharing of memory space between processes. Thus, two programs can reside at the same memory location although at different times.

Memory Management Techniques: The memory management techniques can be classified into management main categories: Contiguous memory management schemes Non-Contiguous memory management schemes Contiguous memory management schemes: In a Contiguous memory memory scheme, each program occupies a single contiguous block of storage locations, memory management in os, i. Single contiguous memory management schemes: The Single contiguous memory management scheme is the simplest memory management scheme used in the earliest generation of computer systems.

In this scheme, the main memory is divided into two contiguous areas or partitions. The operating systems reside permanently in one partition, generally at the management memory, memory management in os, and the user process is loaded into the management partition, memory management in os.

Advantages of Single contiguous memory memory schemes: Simple to implement. Easy to manage and management. In a Single contiguous memory management scheme, memory management in os, once a process is loaded, it is management full processor's time, and no other processor will interrupt it.

Disadvantages of Single contiguous memory management schemes: Wastage of memory space due to unused memory as the process is unlikely to use all the available memory space. The CPU remains idle, waiting for the disk to load the binary image into the main memory. It can not be executed if the memory is too large to fit the entire available main memory space.

It does not support multiprogramming, i. Multiple Partitioning: The single Contiguous memory management scheme is inefficient as it limits computers to execute only one program at a time resulting in memory in memory space and CPU time. The problem of inefficient CPU use can be overcome using multiprogramming that allows more than one program to run concurrently. To switch management two processes, memory management in os, the operating systems need to load both processes into the main memory.

The operating system needs to divide the available main memory into multiple parts to load multiple processes into the main memory. Thus multiple processes can reside in the main memory simultaneously, memory management in os.

The multiple partitioning memories can be of two types: Fixed Partitioning Dynamic Partitioning Fixed Partitioning The management memory is divided into several fixed-sized partitions in a fixed partition memory management scheme or static partitioning. These partitions can be of the same size or different sizes, memory management in os. Each partition can hold a single process. The number of partitions determines the degree of multiprogramming, i, memory management in os.

These partitions are made at the time of system generation and remain fixed after. Advantages of Fixed Partitioning memory management schemes: Simple to implement, memory management in os. Disadvantages of Fixed Partitioning memory management schemes: This scheme suffers from internal fragmentation. The number of partitions is specified at the time of system generation. Dynamic Partitioning The dynamic partitioning was designed to overcome the memories of a fixed partitioning scheme, memory management in os.

In a management partitioning scheme, each process occupies only as much memory as they require when loaded for management. Requested processes are allocated memory until the entire physical memory is exhausted or the remaining space is insufficient to hold the requesting process. In this scheme the partitions used are of memory size, and the number of partitions is not defined at the system generation time.

Advantages of Dynamic Partitioning memory management schemes: Simple to implement. Disadvantages of Dynamic Partitioning memory management schemes: This scheme also suffers from internal fragmentation, memory management in os. The number of partitions is specified at the time of system segmentation.

Non-Contiguous memory management schemes: In a Non-Contiguous memory management scheme, the program is divided into different blocks and loaded at different portions of the memory that need not necessarily be adjacent to one.

This scheme can be classified depending upon the memory of blocks and whether the blocks reside in the main memory or not. What is paging? Paging is a technique that eliminates the requirements of contiguous allocation of main memory. In this, the main memory is divided into fixed-size blocks of management memory called frames. The size of a frame should be kept the same as that of a page to maximize the management memory and avoid external fragmentation.

Advantages of paging:.❷