What If Memory Is Full?

In the process described in the previous lesson, you may notice that we assumed there is plenty of free memory in which to page in a page from swap space. Of course, this may not be the case; memory may be full (or close to it). Thus, the OS might like to first page out one or more pages to make room for the new page(s) the OS is about to bring in. The process of picking a page to kick out, or replace is known as the page-replacement policy.