Consider a virtual memory system that uses the first-in first-out (FIFO)…
2023
Consider a virtual memory system that uses the first-in first-out (FIFO) page-replacement policy and allocates a fixed number of frames to a process.
Assertion (A): Increasing the number of page frames allocated to a process can sometimes increase the page-fault rate.
Reason (R): Some programs do not exhibit locality of reference.
In the light of the above statements, choose the correct answer from the options given below.
- A.
Both A and R are true and R is the correct explanation of A
- B.
Both A and R are true but R is NOT the correct explanation of A
- C.
A is true but R is false
- D.
A is false but R is true
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Correct answer: B
Assertion (A) is true. With FIFO page replacement, increasing the number of page frames can sometimes increase the number of page faults. This phenomenon is known as Belady’s anomaly.
Reason (R) is also true. Some programs do not exhibit strong locality of reference.
However, R is not the correct explanation of A. Belady’s anomaly occurs because of the behavior of the FIFO replacement policy; it is not explained merely by the absence of locality of reference. Therefore, both A and R are true, but R is not the correct explanation of A. Option B is correct.
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