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Operating Systems - David Vernon

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Memory Management<br />

Virtual Memory<br />

– Page Replacement Algorithms<br />

» The Not-Recently-Used Page Replacement<br />

Algorithm<br />

Periodically (e.g. every clock interrupt), reset the<br />

Referenced bit of the page table entry<br />

On a page fault, check the Referenced and Modified bits<br />

of the page table entry<br />

– Class 0: not referenced, not modified<br />

– Class 1: not referenced, modified<br />

– Class 2: referenced, not modified<br />

– Class 3: referenced, modified<br />

Remove a page at random from the lowest numbered<br />

Copyright © 2007 <strong>David</strong> <strong>Vernon</strong> (www.vernon.eu)<br />

non-empty class

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