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Operating Systems - David Vernon

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Memory Management<br />

Virtual Memory<br />

– Paging; Scenario 2<br />

MMU check the present/absent bit in the page table<br />

entry<br />

Page is not pesent so CPU traps to the OS - this trap<br />

is called a page fault<br />

OS finds a little-used page frame and writes its<br />

contents back to disk<br />

It then fetches the page just referenced into the page<br />

frame just made available<br />

It updates the map<br />

Finally, it restarts the trapped instruction<br />

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

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