Question

The following processes are being scheduled using a preemptive, round robin scheduling algorithm. Each process is assigned a numerical priority, with a higher number indicating a higher relative priority. In addition to the processes listed below, the system also has an idle Exercises 309 task (which consumes no CPU resources and is identified as idle). This task has priority 0 and is scheduled whenever the system has no other available processes to run. The length of a time quantum is 10 units. If a process is preempted by a higher-priority process, the preempted process is placed at the end of the queue. a. Show the scheduling order of the processes using a Gantt chart. b. What is the turnaround time for each process? c. What is the waiting time for each process? d. What is the CPU utilization rate?

Answer 1

Answer:

• a) A GANTT chart, also known as a generalised activity normalisation time table, is a sort of diagram in which a number of horizontal lines are displayed to illustrate the quantity of work or production completed in a given period of time in relation to the amount scheduled for those projects.
• (Refer the attached image for this question’s Gantt chart.)

• b) Turnaround time (TAT) is the period of time between when a process is submitted and when it is finished.
• It can alternatively be viewed as the total of the times spent waiting to execute on the CPU, waiting in the ready queue or memory, and performing input/output.

P1:20-0-20,

P2:80-25=55,

P3:90-30=60,

P4:75-60=15,

P5: 120-100 = 20,

P6: 115-105 = 10

• c) The amount of time a process spends in the ready state while it waits for the CPU is known as waiting time.
• Consider, for illustration, that we are utilising the First Come First Serve scheduling algorithm and that the arrival times of the three processes below are 0 ms, 0 ms, and 2 ms.
• The waiting times for the three processes will therefore be as follows: P1: 0 ms

P1:0,

p2:40,

P3:35,

P4:0,

P5:10,

P6:0

• d) The percentage of the CPU utilised during the designated time period is summarised in the CPU Utilization report.
• Typically, the Core uses between 30 and 40 percent of the overall CPU capacity during off-peak times and between 60 and 70 percent at peak times.

105/120 = 87.5 percent.

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