Consider a virtual memory system with FIFO page replacement policy. For an arbitrary page access pattern, increasing the number of page frames in main memory will
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Answer: C
The correct option is C.
This question relates to Belady's Anomaly, which is a phenomenon where increasing the number of physical page frames in main memory results in an increase in the number of page faults for certain page reference patterns under specific page replacement algorithms like FIFO (First-In-First-Out).
For an arbitrary page access pattern, increasing the number of page frames usually decreases the number of page faults, but due to Belady's Anomaly, it can sometimes increase the number of page faults.
Example of Belady's Anomaly:
Consider the page reference string:
1, 2, 3, 4, 1, 2, 5, 1, 2, 3, 4, 5
- With 3 page frames:
- The page faults occur at: 1, 2, 3, 4 (replaces 1), 1 (replaces 2), 2 (replaces 3), 5 (replaces 4), 3 (replaces 1), 4 (replaces 2).
- Total page faults = 9.
- With 4 page frames:
- The page faults occur at: 1, 2, 3, 4, 5 (replaces 1), 1 (replaces 2), 2 (replaces 3), 3 (replaces 4), 4 (replaces 5), 5 (replaces 1).
- Total page faults = 10.
Since the number of page faults increased from 9 to 10 when the number of frames increased from 3 to 4, we conclude that increasing the number of page frames sometimes increases the number of page faults.
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