CIS-4020 Homework #6: Scheduling

Due: Thursday, October 6, 2016

In the text read Chapter 4.

The questions below make use of the information in the following table. This table shows the arrival time of several jobs (CPU bursts) and their processing time in milliseconds.

Process Arrival Time Processing Time
P1 0 10
P2 5 15
P3 8 3
P4 12 8
P5 17 10
  1. Assume no preemption and First Come First Served (FCFS) scheduling. Draw a Gantt chart showing when each process enters the wait queue, when it starts execution, and when it finishes execution. Compute the normalized turn around time for each process and the overall average normalized turn around time.

  2. Repeat question #1 for the Shortest Job Next (SJN) scheduling algorithm.

  3. Suppose a particular job is executed repeatedly with CPU burst times of 5, 6, 12, 4, 6, and 5 milliseconds. Using exponential averaging with α = 0.35 what would you predict the next run time to be? Use the initial run time as the initial value of the estimated run time.

    Exponential averaging computes an updated estimated service time as Tnew = α * Ta + (1 - α) * Told where Ta is the actual service time of the last burst and Told is the old estimated service time.

Last Revised: 2016-09-25
© Copyright 2016 by Peter C. Chapin <>