Suppose two jobs, each of which needs 10 minutes of CPU time, start…
2015
Suppose two jobs, each of which needs 10 minutes of CPU time, start simultaneously. Assume 50% I/O wait time. How long will it take for both to complete, if they run sequentially?
- A.
10
- B.
20
- C.
30
- D.
40
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Correct answer: D
Each job requires 10 minutes of CPU time with a 50% I/O wait rate. This implies the CPU is utilized only half the time, so the actual wall-clock duration per job is 10 divided by 0.5, equaling 20 minutes. Since the jobs run sequentially rather than in parallel, their durations add up to a total of 40 minutes for both.
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