The Demand Paging Method
The following steps are involved in demand paging:
- Initialization of the page: Only a part of a program’s code and data are loaded into physical memory as it begins to execute. The remainder of the program is still on secondary storage.
- Fault Handling on the Page: A page fault is caused when the CPU attempts to access a page that is not in physical memory. The operating system then intervenes to handle the error.
- Page Substitution: To create room for the requested page, the OS chooses a page from physical memory for replacement. For this reason, various page replacement algorithms such as Least Recently Used (LRU) or FIFO are used.
- I/O on disk: The operating system fetches the necessary page from secondary storage (for example, a hard disk) and loads it into a free frame in physical memory. This necessitates a lengthy disk I/O transaction.
- Page Table Refresh: The page table is changed to reflect the page’s new physical memory location.
- Resumption of Execution: Once the page is in physical memory, the CPU can resume program execution as if nothing had happened. Because the requested page is now in RAM, subsequent memory requests are faster.
Example
Assume you have a text editor open on your PC and a large document. Only a few pages of the document are initially put into RAM. New pages are requested from secondary storage as you navigate through the document, resulting in page faults. The operating system manages page faults by loading the necessary pages into RAM and updating the page table.
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.