A process has been allocated 3-page frames. Assume that none of the pages of…
2007
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
Attempted by 39 students.
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Correct answer: A
The optimal page replacement algorithm replaces the page not needed for the longest time. Starting with empty frames, references 1, 2, and 3 cause faults (count: 3). At reference 7, replace page 2. At 4, replace 7. At 5, replace 4. At 6, replace 5. References 3 and 1 hit existing frames. Total page faults equal 7.
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