Page Replacement

Page Replacement

In order to make the most use of virtual memory, we load several processes into memory at the same time. Since we only load the pages that are actually needed by each

process at any given time, there is room to load many more processes than if we had to load in the entire process

what happens if some process suddenly decides it needs more pages and there aren't any free frames available?


This is known as page replacement, and is the most common solution. There are many different algorithms for page replacement


9.4.1 Basic Page Replacement

page-fault processing assumed that there would be free frames available on the free-frame list
Now the page-fault handling must be modified to free up a frame if necessary

Find a free frame:

If there is a free frame, use it.
If there is no free frame, use a page-replacement algorithm to select an existing frame to be replaced, known as the victim frame.

http://www.cs.uic.edu/~jbell/CourseNotes/OperatingSystems/9_VirtualMemory.html