1. What Is FCFS Scheduling?

First-Come, First-Served (FCFS) is a scheduling algorithm where processes are executed in the order they arrive in the ready queue. It is one of the simplest CPU scheduling algorithms and serves as the basis for understanding more complex scheduling methods.

2. How To Calculate Completion Time?

The completion time for a process in FCFS scheduling is calculated using:

Where:

• \( Arrival\ Time \) — Time when the process arrives in the system
• \( Service\ Time \) — Time required by the process for execution (burst time)
• \( Wait\ Time \) — Time the process spends waiting in the ready queue

Explanation: In FCFS scheduling, the completion time represents the total time from process arrival until it completes execution, including both service time and any waiting time in the queue.

3. Importance Of Completion Time Calculation

Details: Calculating completion time is essential for performance evaluation in operating systems. It helps determine system efficiency, calculate turnaround time, and analyze the fairness of the scheduling algorithm.

4. Using The Calculator

Tips: Enter arrival time, service time, and wait time in consistent time units. All values must be non-negative numbers. The calculator will compute the completion time automatically.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between completion time and turnaround time?
A: Completion time is the absolute time when a process finishes, while turnaround time is the total time from arrival to completion (completion time - arrival time).

Q2: How does FCFS handle multiple processes?
A: In FCFS with multiple processes, each process completes before the next one starts. The wait time for subsequent processes includes the service times of all preceding processes.

Q3: What are the advantages of FCFS scheduling?
A: FCFS is simple to implement, fair in the sense that processes are served in arrival order, and easy to understand and analyze.

Q4: What are the disadvantages of FCFS scheduling?
A: It can lead to convoy effect (short processes waiting behind long ones), poor response time for interactive systems, and may not be optimal for average waiting time.

Q5: Can FCFS be used in real-time systems?
A: FCFS is generally not suitable for real-time systems as it doesn't consider process priorities or deadlines, which are critical in real-time environments.