A process has been allocated 3 page frames. Assume that none of the pages of the process are available in the memory initially. The process makes the following sequence of page references (reference string): 1, 2, 1, 3, 7, 4, 5, 6, 3, 1
If optimal page replacement policy is used, how many page faults occur for the above reference string?
(A) 7
(B) 8
(C) 9
(D) 10
Answer: (A)
Explanation: Optimal replacement policy looks forward in time to see which frame to replace on a page fault.
1 23 -> 1,2,3 //page faults
173 ->7
143 ->4
153 -> 5
163 -> 6
Total=7
So Answer is A
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