8. Consider a system running 10 I/O-bound processes and 1 CPU-bound process. Ass

Question

8. Consider a system running 10 I/O-bound processes and 1 CPU-bound process. Assume that the I/O- bound processes issue an I/O operation once for every millisecond of CPU computing and that each I/O operation takes 10 milliseconds to complete (we assume that there is no competition among I/O operations). Assume that the CPU-bound process does not issue anyl/O operations. Around-robin scheduler with quantum size 1 milliseconds is used to schedule all these 11 processes together. We assume that the context-switching overhead is 0.1 millisecond and that all processes are long-running tasks. Calculate the CPU utilization.

Explanation / Answer

a)The time quantum is 1 millisecond:

i. CPU utilization of the tasks 1ms 11 = 11ms

ii. Every task will use up the whole quantum. The I/O operations for the I/O bound tasks will return in time for their next turn. Only non utilizations will be the context switch 11 .1 = 1.1ms.

iii. 1.1ms + 11ms = 12.1ms total time.

iv. 11/12.1 = .909, 90.9%

b) The time quantum is 10 millisecond:

i. Total time (1ms + .1ms) 10 + 10 + .1 = 21.1

ii. CPU utilization of CPU-bound task = 10ms

iii. CPU utilization of I/O bound tasks = 1ms then context switch

iv. 1 10 + 10 = 20ms total CPU utilization v. 20/21.1 = .9478, 94.78%

Related Questions

Navigate

• Browse (All)
• Browse 8
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.