Question

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 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

• A. OPTIMAL = LRU
• B. OPTIMAL < LRU < FIFO
• C. OPTIMAL < FIFO < LRU
• D. OPTIMAL = FIFO

Answer 1

The correct option is C OPTIMAL < FIFO < LRU


LRU :

		3	3	3	1	1	1	4	4
	2	2	2	2	2	3	3	3	1
1	1	1	1	4	4	4	2	2	2

M M M H M M M M MM

$\Rightarrow$ 9 MISS
So optimal < FIFO <LRU