The document provides an overview of the Round Robin scheduling algorithm, a preemptive first-come-first-serve CPU scheduling method that allocates a fixed time slice to processes in a cyclic manner. Key points include its implementation process with various arrival and burst times, along with performance metrics comparing it to other algorithms like FCFS and SJF. Advantages of this algorithm are fair CPU allocation and no starvation, while its disadvantages include high context switching overhead and challenges in determining the optimal time quantum.

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