Operating Systems Chapter 3: Page Replacement Policies Quiz
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Questions and Answers

In the context of page replacement policies, what is the optimal policy if we had knowledge of the future page accesses?

  • Always replace the oldest page in memory
  • Choose the page which will be referenced farthest in the future (correct)
  • Replace the page that has not been used recently
  • Select the most frequently used page for replacement

    • Which replacement policy takes into account the recent references and uses the concept of locality of references?

  • FIFO (First-In-First-Out)
  • NRU (Not-Recently-Used) (correct)
  • Second Chance
  • Clock Algorithm(s)

    • What hardware support is available for each page frame to aid in replacement policies?

  • Least-Recently-Used bit (LRU)
  • Referenced Bit (R) and Modified Bit (M) (correct)
  • Replacement Bit (RB) and Eviction Bit (EB)
  • Frequently Used bit (FU) and Recently Used bit (RU)

    • Which replacement policy involves selecting the page that has not been used recently for replacement?

    <p>FIFO (First-In-First-Out)</p> Signup and view all the answers

    What is the purpose of knowing about the optimal policy in page replacement?

    <p>To improve the performance of real algorithms</p> Signup and view all the answers

    Which replacement policy focuses on selecting the least frequently used page for replacement?

    <p>NFU (Not Frequently Used)</p> Signup and view all the answers

    Which algorithm removes a page at random from the lowest numbered non empty class?

    <p>Not Recently Used (NRU)</p> Signup and view all the answers

    In the FIFO - Second Chance algorithm, what happens to old pages that have been used recently (R=1)?

    <p>They are given a second chance and moved to the end of the list</p> Signup and view all the answers

    What does the 'hand' of the clock algorithm point to when required to evict a page with R=0?

    <p>The page to be replaced</p> Signup and view all the answers

    Which page replacement policy replaces the page in memory that has been unused for the longest time?

    <p>Least Recently Used (LRU)</p> Signup and view all the answers

    What is one possible implementation of the LRU policy that involves updating a list of pages after every memory reference?

    <p>Updating a list of pages, most recently used at front, least at rear</p> Signup and view all the answers

    What characteristic distinguishes the Not Recently Used (NRU) algorithm from other page replacement policies?

    <p>It categorizes pages into four classes based on access time</p> Signup and view all the answers

    In the context of page replacement policies, what is meant by 'dirty bit'?

    <p>A flag indicating whether a page has been modified</p> Signup and view all the answers

    What drawback is associated with the FIFO - Second Chance algorithm?

    <p>Pages keep moving around in its list</p> Signup and view all the answers

    'Hit ratio' is a metric commonly used to measure what aspect of page replacement policies?

    <p>Page replacement accuracy</p> Signup and view all the answers

    'Locality of Reference' implies that...

    <p><strong>Only</strong> pages used in the near past will be used in near future</p> Signup and view all the answers

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