Paging in Computer Architecture and Operating System

Paging is an important topic in memory management. It is also a part of the Operating System and Computer Architecture. Paging is a very important topic for GATE exam also. So you have to clear the concept of paging. I think after going through this slide, your all doubts and concept about paging is cleared. Though if you have some doubt then comment here, you can also message me in my WhatsApp number - [phone]

1. PAGING A PRESENTATION BY ARIJIT ROY COMPUTER SCIENCE & ENGG. DEPT., 2 ND YEAR HOOGHLY ENGINEERING & TECHNOLOGY COLLEGE

2. PROCESSOR AND MEMORY INTERCONNECTION

3. PROCESSOR & MEMORY INTERACTION Processor executes different processes within it. To execute a particular process, processor will call that process. But there is a fact. Within the memory a process cannot store itself as a whole. Here the concept of paging comes.

4. PAGING A process is divided into some smaller parts , known as page. In another way we can say that a page is the smallest length of contiguous block of physical memory. We take an example, that will make easier to understand the concept of page. Suppose a process has a size of 4 Bytes. This process is divided into 2 pages. Each page consists of 2 Bytes. So, every page size is 2 Bytes. Here, Bytes are also called as word.

5. INSIDE THE SECONDARY MEMORY There are several processes that are kept inside the secondary memory storage. A bunch of processes are kept as a unit inside the secondary storage device. Suppose, we consider HDD (Hard Disk Drive) as a secondary storage device. There are several tracks in HDD. Each track consists of many sectors. Every Sector stores different processes and data as a bunch in a sequential order.

6. SECONDARY STORAGE DEVICE

7. HOW A PROCESS COMES INSIDE RAM THROUGH PAGING When processor needs a word then it generates an address and according to the address processor will search the word in Cache and RAM. If it is not found in main memory then Operating system takes the control in its hand. It searches in secondary memory. OS trace that inside which process that required word is present. When that process is found then according to paging, process is divided into several pages of equal size. Then that pages are transferred into RAM.

8. DIAGRAMMATIC EXPLANATION OF PAGING

9. DIAGRAMMATIC EXPLANATION OF PAGING

10. DIAGRAMMATIC EXPLANATION OF PAGING

11. DIAGRAMMATIC EXPLANATION OF PAGING W 1

12. DIAGRAMMATIC EXPLANATION OF PAGING W 1

13. DIAGRAMMATIC EXPLANATION OF PAGING

14. DIAGRAMMATIC EXPLANATION OF PAGING W W 1 W 2 W 3

15. DIAGRAMMATIC EXPLANATION OF PAGING W W 1 W 2 W 3

16. DIAGRAMMATIC EXPLANATION OF PAGING W W 1 W 2 W 3

17. DIAGRAMMATIC EXPLANATION OF PAGING W W 1 W 2 W 3

18. DIAGRAMMATIC EXPLANATION OF PAGING

19. DIAGRAMMATIC EXPLANATION OF PAGING SUPPOSE, ALL THE FRAMES ARE FULL WITH DIFFERENT PAGES. THAT MEANS, IN THIS SITUATION RAM IS FULL. NOW IF I NEED TO PLACE SOME ANOTHER NEW PAGE INTO RAM, THEN WHAT HAPPENS? HOW IT CAN BE POSSIBLE?

20. SOLUTION IS PAGE REPLACEMENT So we have to place some pages into secondary storage and the required process will divide into pages and that pages will take place inside that empty frames. This is known as Page Replacement. This paging and page replacement is controlled by Operating System (OS). Placing of a page from the secondary storage to an empty frame is known as Roll In / Swap In. Placing of a page from a frame to the secondary memory is known as Roll Out / Swap Out.

21. DIFFERENT PAGE REPLACEMENT ALGORITHMS So, which page OS have to roll out from the RAM, that depends on different types of page replacement algorithms. Some important page replacement algorithms are – 1. FIFO / FCFS Page Replacement Algorithm 2. LRU Page Replacement Algorithm. 3. LFU Page Replacement Algorithm. 4. Optimal Page Replacement Algorithm. 5. MFU Page Replacement Algorithm. 6. Clock Page Replacement Algorithm, etc.

22. So, In the next classes we will discuss different types of page replacement algorithms.

23. I think you guys understand it and enjoy this slide. See you in the next class. STAY HOME , STAY SAFE……