CSC 553 - Operating Systems

Dr. R. M. Siegfried

Assignment #9 - p. 428-429/9.1, 9.3

Due Tuesday, November 14, 2023

9.1

Consider the following workload:
Process Burst Time Priority Arrival time
P1 50 ms 4 0 ms
P2 20 ms 1 20 ms
P3 100 ms 3 40 ms
P4 40 ms 3 60 ms

  1. Show the schedule using shortest remaining time, nonpreemptive priority (a smaller priority number implies higher priority) and round robin with quantum = 30 ms. Use a time scale diagram as shown below for FCFS example to show the schedule for each requested scheduling policy
    2. Example for FCS (1 unit = 10 ms)
    P1 P1 P1 P1 P1 P2 P2 P3 P3 P3 P3 P3 P3 P3 P3 P3 P3 P4 P4 P4 P4
    0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
  2. What is the average waiting time of the above scheduling policies?

9.3

Show that, among nonpreemptive scheduling algorithms, SPN provides the minimum average waiting time for a batch of jobs that arrive at the same time. Assume that the scheduler must always execute a task if one is available.

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