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    Question

    In the context of memory management, which of the

    following page replacement algorithms suffers from Belady's Anomaly?
    A Optimal Page Replacement Correct Answer Incorrect Answer
    B Least Recently Used (LRU) Correct Answer Incorrect Answer
    C Most Recently Used (MRU) Correct Answer Incorrect Answer
    D First-In-First-Out (FIFO) Correct Answer Incorrect Answer
    E Clock Algorithm Correct Answer Incorrect Answer

    Solution

    First-In-First-Out (FIFO) page replacement algorithm replaces the oldest page in memory when a page fault occurs. While simple and easy to implement, FIFO is prone to Belady's Anomaly, where increasing the number of frames paradoxically results in more page faults. This counterintuitive behavior occurs because the algorithm does not consider page usage patterns and blindly removes the oldest page, even if it is frequently accessed. For example, in a specific reference string, adding more frames can displace frequently used pages, causing additional page faults. This makes FIFO less efficient for modern systems compared to algorithms like LRU or Optimal Replacement. Why Other Options Are Incorrect: 1. Optimal Page Replacement: Guarantees the minimum number of page faults by replacing the page that will not be used for the longest time, thus immune to Belady's Anomaly. 2. LRU: Replaces the least recently used page, considering actual usage patterns, avoiding the anomaly. 3. MRU: Replaces the most recently used page, generally not susceptible to Belady's Anomaly. 4. Clock Algorithm: A variation of FIFO that uses a reference bit to approximate LRU, mitigating the anomaly. FIFO’s susceptibility to Belady’s Anomaly underscores the importance of using more sophisticated algorithms like LRU in systems requiring efficient memory management.

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