Description
1. (70pts)
Consider the following set of processes, with the arrival time and the length of the CPU burst given in milliseconds:
Process Arrival Time Burst Time Priority
P1 0 10 3
P2 1 1 1
P3 2 2 3
P4 3 1 4
P5 4 5 2
Assume the computer system has only one CPU.
a. Show Gantt charts that illustrate the execution of these processes using the following scheduling algorithms:
FCFS,
non-preemptive SJF,
preemptive priority (a smaller priority number implies a higher priority),
and RR (quantum = 2).
No context-switch time is considered.
b. What is the turnaround time of each process for each of the scheduling algorithms in part a?
c. What is average waiting time of all the processes for each of the scheduling algorithms?
2. (30pts)
Consider a system running ten I/O-bound tasks and one CPU-bound task. Assume that the I/O-bound tasks issue an I/O operation once for every millisecond of CPU computing and that each I/O operation takes 10 milliseconds to complete; the CPU-bound task performs only computations. Also assume that the context-switching overhead is 0.1 milli-second and that all processes are long-running tasks. Find out the CPU utilization for a round-robin scheduler when:
a. The time quantum is 1 millisecond
b. The time quantum is 10 milliseconds