Algorithms for Demand Paging
Below mentioned are the algorithms for the Demand Paging used in Operating Systems.
1. FIFO (First in First out)
The FIFO algorithm replaces the oldest page in memory with the new page when a page fault occurs.
Initial state: Empty memory frames.
Page references: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.
Page faults: 1, 2, 3, 4 (filling up memory)
5 (replaces 1, as it's the oldest)
6 (replaces 2)
7 (replaces 3)
8 (replaces 4)
9 (replaces 5)
10 (replaces 6)
Total page faults: 7
2. LRU (Least Recently Used)
LRU replaces pages that have not been used for a long time. It works well in many situations but can be very cumbersome as it needs to keep track of the order in which pages are used.
Initial state: Empty memory frames.
Page references: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.
Page faults: 1, 2, 3, 4 (filling up memory)
5 (replaces 1, as it's the least recently used)
6 (replaces 2)
7 (replaces 3)
8 (replaces 4)
9 (replaces 5)
10 (replaces 6)
Total page faults: 7
3. LFU (Least Frequently Used)
LFU replaces the least number of pages. It focuses on removing pages that are not frequently visited.
Initial state: Empty memory frames.
Page references: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10.
Page faults: 1, 2, 3, 4 (filling up memory)
5 (replaces 1, as it's the least frequently used)
6 (replaces 2)
7 (replaces 3)
8 (replaces 4)
9 (replaces 5)
10 (replaces 6)
Total page faults: 7
4. Optimal Page Replacement
The algorithm is theoretical and requires knowledge of future page access; It is impossible to achieve this. It is impossible to follow the application.
Algorithms For Demand Paging in OS
The operating system is necessary for managing computer resources and using hardware efficiently. Memory management involves allocating and releasing memory for various programs and files and is one of the most important aspects of modern working. Operating systems use a variety of methods to provide efficient memory management; one of them is request pagination. In this article, we will learn what paging is in the business context, why it is important, and how it improves computer performance.
Demand paging is a memory management technique used in operating systems to manage the allocation of physical memory (RAM) to ongoing programs in an effective manner. It is a fundamental component of current operating systems that helps them to make the greatest use of available memory resources while decreasing the time it takes to access data from secondary storage, such as hard disks or SSDs.