Practice Description Of The Anomaly (19.7.1) - Approximate LRU Implementation

Practice: Description of the Anomaly

Lesson 19.7.1Approximate LRU Implementation

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6 sample questions

Question 1.
What is the purpose of the reference bit in the approximate LRU algorithm?
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Think about how the system remembers page usage.
Question 2.
Can you explain Belady's anomaly in simple terms?
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Consider how FIFO might not always select the most appropriate page to replace.
3Question 3.
What does the reference bit signify in the approximate LRU?
- To mark the least used page
- To indicate a page was accessed recently
- To store frequency of use
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Remember how the bit reflects recent activity.
4Question 4.
True or False: Belady's anomaly can occur in any page replacement algorithm.
- True
- False
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Consider which algorithms are impacted by memory management decisions.
Question 5.
Assume you have 4 page frames, and a reference string as follows: 1, 2, 3, 4, 1, 2, 5, 1, 2, 3, 4, 5. Calculate page faults for FIFO, LRU, and Optimal algorithms, discuss which is most efficient.
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Map page replacements based on algorithm characteristics.
Question 6.
Develop a scenario in which Belady's anomaly appears with a page reference string of your choosing. Explain the phenomenon observed.
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Construct a sequence that forces earlier references to be replaced unnecessarily.

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