FCFS (First Come First Served) in Operating Systems - Mini Project: Build & Apply

FCFS (First Come First Served) Scheduling Simulation

📖 Scenario: You are managing a simple computer system that runs tasks one after another in the order they arrive. This method is called First Come First Served (FCFS) scheduling.Each task has a name and a time it needs to run. You want to organize these tasks and calculate how long each task waits before it starts running.

🎯 Goal: Create a list of tasks with their arrival order and run times. Then, calculate the waiting time for each task using the FCFS method.

📋 What You'll Learn

Create a list of tasks with exact names and run times

Add a variable to track the current time as tasks are processed

Use a loop to calculate waiting times for each task in FCFS order

Add the waiting time information to each task

💡 Why This Matters

🌍 Real World

FCFS scheduling is used in simple operating systems and batch processing where tasks are handled in the order they arrive.

💼 Career

Understanding FCFS helps in roles like system administration, software development, and IT support where task scheduling and resource management are important.

1

Create the list of tasks

Create a list called tasks with these exact dictionaries in order: {'name': 'Task1', 'run_time': 4}, {'name': 'Task2', 'run_time': 3}, {'name': 'Task3', 'run_time': 1}, {'name': 'Task4', 'run_time': 2}.

Operating Systems

# Create the list of tasks with their names and run times
# Your code here

Need a hint?

Use a list with dictionaries. Each dictionary has keys 'name' and 'run_time' with the exact values given.

2

Add a variable to track current time

Create a variable called current_time and set it to 0. This will track the time as tasks run.

Operating Systems

tasks = [
    {'name': 'Task1', 'run_time': 4},
    {'name': 'Task2', 'run_time': 3},
    {'name': 'Task3', 'run_time': 1},
    {'name': 'Task4', 'run_time': 2}
]
# Create current_time variable and set to 0
# Your code here

Need a hint?

Just create a variable named current_time and assign it zero.

3

Calculate waiting times for each task

Use a for loop with variable task to go through tasks. For each task, add a new key 'waiting_time' with the value of current_time. Then increase current_time by task['run_time'].

Operating Systems

tasks = [
    {'name': 'Task1', 'run_time': 4},
    {'name': 'Task2', 'run_time': 3},
    {'name': 'Task3', 'run_time': 1},
    {'name': 'Task4', 'run_time': 2}
]
current_time = 0
# Use a for loop to add waiting_time to each task and update current_time
# Your code here

Need a hint?

Loop over tasks, set waiting_time to current_time, then add run_time to current_time.

4

Add total waiting time calculation

Create a variable called total_waiting_time and set it to 0. Then use a for loop with variable task to add each task['waiting_time'] to total_waiting_time.

Operating Systems

tasks = [
    {'name': 'Task1', 'run_time': 4},
    {'name': 'Task2', 'run_time': 3},
    {'name': 'Task3', 'run_time': 1},
    {'name': 'Task4', 'run_time': 2}
]
current_time = 0
for task in tasks:
    task['waiting_time'] = current_time
    current_time += task['run_time']
# Calculate total_waiting_time by summing waiting_time of all tasks
# Your code here

Need a hint?

Initialize total_waiting_time to zero, then add each task's waiting_time in a loop.