Scheduling Policies for Preemptive Scheduling

Scheduling Policies for Preemptive Scheduling - Scheduling...

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Scheduling Policies for Preemptive Scheduling Two policies: Round Robin Multilevel Feedback-Queue Scheduling Round Robin Ready processes are in a queue. Every time that a time quantum expires, a process is dequeued from the front of the queue and put in running state The previous running process is added to the end of the queue.
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Round Robin Round Robin (cont.) (T=10ms) Process Burst Time p1 24ms p2 3ms p3 3ms 3 10 P3 P1 P2 Average completion time = (13+16+30)/3=19.6ms 3 P1 10 P1 4
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Quantum Length Analysis What is the impact of quantum length? Assume T=10ms. Process Burst Time p1 20ms p2 1ms p3 1ms 1 10 P3 P1 P2 Average completion time = (11+12+22)/3=15ms 1 P1 10
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Quantum Length Analysis What if we choose a smaller quantum length?Assume T=1ms. Process Burst Time p1 20ms p2 1ms p3 1ms 1 1 P3 P1 P2 Average completion time = (2+3+22)/3=9ms 1 P1 T=1ms P1 1 1 P1 P1 1 1
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Quantum Length Analysis The shorter the quantum, the shorter the average completion time. Based on this we could make the quantum time
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This note was uploaded on 01/30/2012 for the course CS 252 taught by Professor Gustavorodriguez during the Fall '11 term at Purdue University-West Lafayette.

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Scheduling Policies for Preemptive Scheduling - Scheduling...

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