First in, First out and Round Robin CPU Scheduling

CPU Scheduling

1. CPU Scheduling Round Robin Armen Bacuteng Ryan Czar Rayray Joshua Roman Reyes Ralph Gylan Asistin Gwen Bustamante Anne Kylie Binong

2. INTRODUCTION Schedule shows the methods in order assigned to operate on available central processing unit (CPU). Fixed CPU timing Methods or algorithms have been developed. The main objective of these algorithms is. For maximum CPU usage, Average Waiting Time (AWT), Average turnaround time (ATAT), NCS, increase throughput and do their best to be fair to everyone. Some examples of CPU Scheduling are First Come First Serve (FCFS), Preemptive Shortest Job First (PSJF), Round Robin (RR) which are valuable assets of CPU Scheduling.

3. ROUND ROBIN 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. The Round robin scheduling algorithm is one of the CPU scheduling algorithms in which every process gets a fixed amount of time quantum  This processing is done in FIFO order which suggests that processes are executed on a first-come, first-serve basis.

4. ROUND ROBIN Computing the round robin is a clock -driven process, all the processes are added to the ready queue. First, the burst time of every process is compared to the time quantum of the CPU. If the burst time of the process is less than or equal to the time quantum in the round-robin scheduling algorithm, the process is executed to its burst time. If the burst time of the process is greater than the time quantum, the process is executed up to the time quantum (TQ). When the time quantum expires, it checks if the process is executed completely or not.

5. HOW TO SOLVE ROUND ROBIN? After knowing the time quantum, burst time and arrival time of a certain processes, solve the following: Gantt Chart CPU Efficiency x 100 Throughput Average Waiting Time = Response Time – Arrival Time Average Turn Around Time = Finish Time – Arrival Time   TBT = Total Burst Time TFT = Total Finish Time

6. Let’s try this! Time Quantum - 2 Process Burst Time Arrival Time P1 1 4 P2 6 P3 2 2 P4 3 4 P5 4 2

7. Let’s try this! Time Quantum - 2 Process Burst Time Arrival Time P1 1 4 P2 6 P3 2 2 P4 3 4 P5 4 2

8. Let’s try this! Time Quantum - 4

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