Operating System
3. In a computer system, there is one CPU and two external devices IO1 and IO2, now three jobs J1, J2 and J3 are already in the main memory to be run, the priority of them is J1>J2>J3. The order and time they use the CPU and devices are as following:
J1:IO2(30ms),CPU(10ms),IO1(30ms),CPU(10ms).
J2:IO1(20ms),CPU(20ms),IO2(40ms).
J3:CPU(30ms),IO1(20ms).
Now they run at the same time and the use of resources is preemptive, please answer the following questions(you need not consider other operating times):
Calculate the time J1, J2, J3 cost from start to finish separately.
What is the CPU utilization when three jobs are finishing?
What is the IO1's utilization when three jobs are finishing?
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