Consider the virtual page reference string: 1, 2, 3, 2,

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Consider the virtual page reference string: 1, 2, 3, 2, 4, 1, 3, 2, 4, 1 On a demand paged virtual memory system running on a computer system that has main memory size of 3 page frames which are initially empty. Let LRU FIFO and OPTIMAL denote the number of page faults under the corresponding page replacement policy. Then,

1. OPTIMAL < LRU < FIFO
2. OPTIMAL < FIFO < LRU
3. OPTIMAL = LRU
4. OPTIMAL = FIFO

Correct Option: B

Reference string:
1, 2, 3, 2, 4, 1, 3, 2, 4, 1
3 page frames.
FIFO

There are 6 page faults.
Optimal

There are 5 page faults.
LRU

There are 9 page faults. Hence, OPTIMAL < FIFO < LRU