![]() ![]() When 3 comes, it is already in memory so -> 0 Page Faults. Initially all slots are empty, so when 1, 3, 0 came they are allocated to the empty slots -> 3 Page Faults. When a page needs to be replaced page in the front of the queue is selected for removal.Ĭonsider page reference string 1, 3, 0, 3, 5, 6 with 3 page frames. System keeps track of all pages in the memory in a queue the oldest page is in theįront of the queue. This is the simplest page replacement algorithm. In other words, the page, which resides at the rare end of the queue, will be replaced on the every page fault. The page, which is assigned the frame first, will be replaced first. ⦁ FIFO → in this algorithm, a queue is maintained. Is just opposite to the optimal page replacement algorithm. Replaces the page, which has not been referred for a long time. ⦁ Least recent used (LRU) page replacement algorithm → this algorithm Implementable but it can be used as a benchmark. ⦁ Optimal Page Replacement algorithm → this algorithms replaces the page, which will not be referred for so long in future. Each algorithm has a different method by which the pages can be replaced. There are various page replacement algorithms. Frame allocation is all about how many frames are to be allocated to the process while the page replacement is all about determining the page number, which needs to be replaced in order to make space for the requested page. It is very important to have the optimal frame allocation and page replacement algorithm. ![]() Page replacement is done when the requested page is not found in the main memory (page fault). The process of replacement is sometimes called swap out or write to disk. Here after allocating 1, 2 and 3 now the memory is full, so for inserting 4 we will look for the page which is not again referred in near future from 1, 2 and 3 so page 3 is not in near future so we replace that page with new page 4, and so on we will repeat the steps till we reach the end.The page replacement algorithm decides which memory page is to be replaced. Let’s understand by using an example and explaining it diagrammatically. In Optimal page replacement we replace the page which is not referred to the near future, although it can’t be practically implemented, but this is most optimal and have minimal miss, and is most optimal. A page replacement algorithm is an algorithm which decides which memory page is to be replaced. ![]() Optimal page replacement algorithm is a page replacement algorithm. What is Optimal Page Replacement Algorithm? Given page number and page size the task is to find number of hits and misses as when we allocate the memory block to a page using Optimal Page Replacement Algorithm. ![]()
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