Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

The following processes are being scheduled using a preemptive, round-robin sche

ID: 3667884 • Letter: T

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 task (which consumes no CPU resources and is identified as P_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. Show the scheduling order of the processes using a Gantt chart. What is the turnaround time for each process? What is the waiting time for each process? What is the CPU utilization rate?

Explanation / Answer

0 10 20 25 35 45 55 65 75 80 85 90   100 110 120

b) Turnaround Time= process completion time - submission time.

P1= 20 ; P2= 60 (85-25) ; P3= 55 (90-35) ; P4= 15 (80-65) ; P5= 10 (110-100) ; P6= 10 (120-110);

c) Waiting Time:

P1=0 ; P2= 35 (0+10+(80-55)) ; P3= 35 (5+ 10 + (85-65)); P4=5 ; P5= 0 ; P6= 5;

d) CPU utilization rate :

= (105/ 120) * 100 => 87.5%

P1 P1 Pidle P2 P3 P2 P3 P4 P4 P2 P3 Pidle P5 P6