1. What Is First-Come First-Served Waiting Time?

First-Come First-Served (FCFS) waiting time represents the duration a process waits in the ready queue before its execution begins. It is a fundamental metric in scheduling algorithms that determines process fairness and system efficiency.

2. How Does The Calculator Work?

The calculator uses the FCFS waiting time formula:

Where:

• \( Waiting Time \) — Time process spends waiting in queue (time units)
• \( Start Time \) — Time when process begins execution (time units)
• \( Arrival Time \) — Time when process arrives in system (time units)

Explanation: The formula calculates the difference between when a process starts execution and when it first arrived in the system, representing the actual waiting period in the ready queue.

3. Importance Of Waiting Time Calculation

Details: Waiting time is crucial for evaluating scheduling algorithm performance, optimizing system throughput, ensuring fairness among processes, and analyzing system efficiency in operating systems and queuing theory.

4. Using The Calculator

Tips: Enter start time and arrival time in consistent time units (seconds, milliseconds, etc.). Ensure arrival time is less than or equal to start time for valid results. All values must be non-negative.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between waiting time and turnaround time?
A: Waiting time is only the time spent waiting in queue, while turnaround time includes both waiting time and execution time (Turnaround Time = Completion Time - Arrival Time).

Q2: Can waiting time be negative?
A: No, waiting time cannot be negative. If arrival time is after start time, it indicates invalid input as a process cannot start before it arrives.

Q3: Why is FCFS scheduling considered non-preemptive?
A: FCFS is non-preemptive because once a process starts execution, it runs to completion without being interrupted by newly arriving processes.

Q4: What are the advantages of FCFS scheduling?
A: Advantages include simplicity, fairness in process ordering, and no starvation since every process eventually gets CPU time.

Q5: What are the disadvantages of FCFS scheduling?
A: Disadvantages include convoy effect (short processes waiting behind long ones), poor average waiting time, and not suitable for time-sharing systems.