Program with page replacement algorithms - an OS problem.
Lets's study algorithm!!! Some assignments from Bachelor degree of Computer Science.
#Optimal page replacement algorithm in java code. If( choice!= 1 & choice!= 2 & choice!= 3 & choice!= 4 ) String inputString //String variable for the input string and array of Strings for the pages Int frameSize, page= 0, choice, n //Declare variables for: frame size, page, choice, and size n ReplacementPolicy.java package replacementpolicy Since it was used heavily, it has a large frequency count and remains in memory even if it is no longer needed.ġ.Two arrays, page and frame, where n is the number of pages and f_size is the size of the frame bufferĢ.An array cnt is used to store and keep track of the tally or frequency of usage of the pagesģ.When a page fault occurs, it replaces the page with the least frequency of usageĤ.If there are more than 1 page that the least frequency of usage, use FIFO logic and replace the page that came first among those least frequently used pages. This algorithm suffers from the situation in which a page is used heavily during the staring phase of aprocess, but then is never again. The reason for this selection is that a mostly used page should have a larger reference count. The page which has the smallest count is going to be replaced. On a page fault, the frame that was least recently used is replaced.Ģ.Two additional arrays, a & b, where a stores the sorted list of pages from most recently used to least recently used and b is the temporary array used to update the listģ.When page fault occurs, it finds the index of the LRU from frame based on the last element of a and replaces that pageĤ.Each time a page is referenced, update a LFU (Least Frequently Used). We insert page at the tail of the queue when a page is added into the memory disk.ġ.Two arrays, page and frame (queue), where n is the number of pages and f_size is the size of the frame bufferĢ.When there is page fault, it replaces the page in the frame after the previously replaced frame LRU (Least Recently Used) 
At the head of the queue we replace the page. We can create a FIFO queue to hold all the pages present in the memory disk.
The oldest page is chosen when a page is going to be replaced. A FIFO replacement algorithm links with each page the time when that page was added into the memory. A page replacement algorithm is said to satisfy the inclusion property or is called a stack algorithm if the set of pages in an n-frame memory is always a subset of the pages in a(n + 1) frame memory. If the selected page has been modified, it must be copied back to disk (swapped out). If there is no available frame in memory, then one page is selected for replacement. When page fault occurs, the referenced page must be loaded.
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