RoundRobin scheduling algorithm implementation, and comparison with other states of art scheduling algorithms

1. Operating Systems Laboratory
Department: CSE
Course Code: CSE 4510
Section: E
Trimester: Fall 2023
Members
Course Teacher : Gourab Saha
Md. Abdur Rahman 011202260
Shojib Talukder 011201345

2. Round Robin Scheduling
The Round-robin scheduling algorithm is a kind of
preemptive First come, First Serve CPU Scheduling
algorithm where each process in the ready state gets the
CPU for a fixed time in a cyclic way (turn by turn). It is the
oldest scheduling algorithm, which is mainly used for
multitasking.

3. How Does It Works?
❏ In the RR algorithm, a fixed time quantum is assigned to each process in the ready queue
❏ If the process completes its execution within the time quantum, it is removed from the queue
❏ If not, it is placed back in the queue, and the next process in the queue is given a chance to
execute. This process continues until all processes in the queue have executed.

4. Implementation
Process Arrival Time Burst Time
P0 0 3
P1 2 5
P2 3 1
TIME SLICE = 2

5. Process Arrival Time Burst Time
P0 0 3 1
P1 2 5
P2 3 1
Implementation
P0
0 2 4 5 6 8 9

6. Process Arrival Time Burst Time
P0 0 1
P1 2 5 3
P2 3 1
Implementation
P0 P1
0 2 4 5 6 8 9

7. Process Arrival Time Burst Time
P0 0 1
P1 2 3
P2 3 1 0
Implementation
P0 P1 P2
0 2 4 5 6 8 9

8. Process Arrival Time Burst Time
P0 0 1 0
P1 2 3
Implementation
P0 P1 P2 P0
0 2 4 5 6 8 9

9. Process Arrival Time Burst Time
P1 2 3 1
Implementation
P0 P1 P2 P0 P1
0 2 4 5 6 8 9

10. Process Arrival Time Burst Time
P1 2 1 0
Implementation
P0 P1 P2 P0 P1 P1
0 2 4 5 6 8 9

11. PERFORMANCE
❏ ResponseTimeAVG = 0.33
❏ WaitingTimeAVG = 2.33
❏ TurnAroundTime = 5.33

12. PERFORMANCE COMPARISON
Algorithms WaitingTimeavg ResponseTimeage
FCFS 2 2
SJF (preemptive) 0.66 0.66
SJF (non-preemptive) 0.66 0.66
RoundRobin 2.23 0.33

13. ADVANTAGE
❏ No starvation problem
❏ No convoy effect
❏ Fair allocation of CPU
❏ Best average response time *

14. DISADVANTAGE
❏ Not ideal where process priority are important
❏ Higher context switching overhead if sliced time is low
❏ Doesn’t have optimal average waiting time
❏ Difficult to find a correct time quantum

15. THANK YOU