CPU Scheduling Calculator – FCFS, SJF & Round Robin

The CPU Scheduling Calculator is a powerful tool designed for students, developers, and computer science professionals to analyze and calculate scheduling performance metrics. It helps compute waiting time and turnaround time for various CPU scheduling algorithms such as First Come First Serve (FCFS), Shortest Job First (SJF), and Round Robin.

CPU scheduling is a fundamental concept in operating systems that determines how processes are assigned to the CPU. Efficient scheduling improves system performance, reduces waiting time, and maximizes CPU utilization.

What is CPU Scheduling?

CPU scheduling is the process by which an operating system decides which process will use the CPU at a given time. Since multiple processes compete for CPU time, scheduling algorithms are used to manage execution efficiently.

Types of CPU Scheduling Algorithms

1. First Come First Serve (FCFS)

FCFS is the simplest scheduling algorithm where processes are executed in the order they arrive. It is easy to implement but may lead to long waiting times.

2. Shortest Job First (SJF)

SJF selects the process with the smallest burst time. It reduces average waiting time but requires knowledge of execution time.

3. Round Robin (RR)

Round Robin assigns a fixed time quantum to each process. It ensures fairness and is widely used in time-sharing systems.

Why Use This CPU Scheduling Calculator?

• Instant calculation of waiting and turnaround time
• Supports major scheduling algorithms
• Useful for students and exam preparation
• Helps understand OS concepts visually
• Works on mobile and desktop

Applications

CPU scheduling is used in operating systems, multitasking environments, real-time systems, and cloud computing platforms to optimize performance and resource utilization.

Example

For burst times 5, 8, 2, and 6 using SJF scheduling, the shortest job executes first, reducing overall waiting time compared to FCFS.

Tips for Better Understanding

• Always arrange processes based on algorithm rules
• Understand difference between waiting and turnaround time
• Practice with different datasets
• Compare multiple algorithms

Frequently Asked Questions

What is waiting time?

Waiting time is the total time a process waits in the ready queue before execution.

What is turnaround time?

Turnaround time is the total time from process arrival to completion.

Which scheduling algorithm is best?

It depends on system requirements. SJF is optimal for average waiting time, while Round Robin ensures fairness.