If an instruction takes i microseconds and a page fault takes an additional j…
1998
If an instruction takes i microseconds and a page fault takes an additional j microseconds, the effective instruction time if, on average, a page fault occurs every k instructions is:
- A.
i + j/k
- B.
i + j * k
- C.
(i + j)/k
- D.
(i + j) * k
Attempted by 14 students.
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Correct answer: A
The normal execution time of each instruction is i microseconds. A page fault adds j microseconds, but it occurs only once every k instructions on average. Therefore, the extra page-fault overhead per instruction is j/k microseconds. Effective instruction time = normal instruction time + average page-fault overhead = i + j/k.