Module4Assign3

This project is a CPU scheduling simulator written in C++. It allows you to simulate multiple CPU scheduling algorithms, visualize their Gantt charts, and calculate performance metrics such as average waiting time, turnaround time, CPU utilization, and throughput.

Table of Contents

• Features
• Schedulers Implemented
• Getting Started
• Usage
• Input File Format
• Random Process Generation
• Output
• Future Enhancements
• Project Structure
• Scheduler Cheat-Sheet

Features

• Implements multiple CPU scheduling algorithms: RR, FCFS, SRTF, Priority, EDF, MLFQ, MLQ, Lottery, CFS, SJF.
• Gantt chart generation to visualize execution order.
• Metrics calculation:
  • Average waiting time
  • Average turnaround time
  • CPU utilization
  • Throughput
• Supports randomly generated processes.
• Supports input from a text file.
• Logging to an optional output file.

Schedulers Implemented

• Round Robin (RR) – Preemptive, uses quantum.
• First-Come-First-Serve (FCFS) – Non-preemptive.
• Shortest Job First (SJF) – Non-preemptive.
• Shortest Remaining Time First (SRTF) – Preemptive.
• Priority Scheduling – Can implement aging to prevent starvation.
• Multilevel Queue (MLQ) – Predefined queues with different priorities.
• Multilevel Feedback Queue (MLFQ) – Dynamic queues based on behavior.
• Lottery Scheduling – Randomized selection based on tickets.
• Completely Fair Scheduler (CFS) – Uses virtual runtime.
• Earliest Deadline First (EDF) – Preemptive, uses deadlines.

Other schedulers like CFS or Lottery can be extended via the Scheduler base class.

Getting Started

Requirements

• C++17 compatible compiler (e.g., g++)
• Terminal or command line

Compile

# Compile only the main simulator:
g++ simulator.cpp -o simulator

# Or compile with all scheduler files:
g++ simulator.cpp fcfs.cpp sjf.cpp srtf.cpp priority.cpp rr.cpp mlq.cpp mlfq.cpp lottery.cpp cfs.cpp edf.cpp -o simulator

Usage

Basic command structure:

./simulator --scheduler <scheduler_type> [--input <file>] [--quantum <n>] [--random] [--num <n>] [--output <log_file>]

Examples:

./simulator --scheduler rr
./simulator --scheduler rr --quantum 3
./simulator --scheduler fcfs --input tasks.txt
./simulator --scheduler srtf --input tasks.txt
./simulator --scheduler rr --random
./simulator --scheduler rr --random --num 20
./simulator --scheduler rr --random --output log.txt

Input File Format

Optional .txt file with process information. Each line represents one process:

<id> <arrival_time> <burst_time> <priority>

Example (tasks.txt):

P1 0 8 2
P2 1 4 1
P3 2 9 3
P4 3 5 4

Random Process Generation

Use --random to generate random processes. By default generates 10 processes. Use --num <n> to generate a custom number of processes.

Output

• Gantt Chart – Shows execution order of processes.
• Metrics – Displays average waiting time, turnaround time, CPU utilization, and throughput.
• Optional log file can store the Gantt chart and metrics.

Future Enhancements

• Implement additional schedulers: more variations of CFS, MLQ, MLFQ.
• Add I/O simulation for realistic scenarios.
• Support deadlines or weights from input file.
• Simulate multi-core CPU environment.
• Add GUI visualization of Gantt chart.

Project Structure

simulator.cpp      # Main simulator and RR scheduler
fcfs.cpp           # FCFS scheduler
sjf.cpp            # SJF scheduler
srtf.cpp           # SRTF scheduler
priority.cpp       # Priority scheduler
rr.cpp             # Round Robin scheduler
mlq.cpp            # Multilevel Queue scheduler
mlfq.cpp           # Multilevel Feedback Queue scheduler
lottery.cpp        # Lottery scheduler
cfs.cpp            # Completely Fair Scheduler
edf.cpp            # EDF scheduler
tasks.txt          # Sample input file
README.md          # Project documentation

Scheduler Cheat-Sheet

Scheduler	Command Example	Notes
RR	./simulator --scheduler rr	Default quantum = 4
RR custom quantum	./simulator --scheduler rr --quantum 3	Preemptive
FCFS	./simulator --scheduler fcfs --input tasks.txt	Non-preemptive
SJF	./simulator --scheduler sjf --input tasks.txt	Non-preemptive
SRTF	./simulator --scheduler srtf --input tasks.txt	Preemptive
Priority	./simulator --scheduler priority --input tasks.txt	Can implement aging
MLQ	./simulator --scheduler mlq --input tasks.txt	Multiple fixed-priority queues
MLFQ	./simulator --scheduler mlfq --input tasks.txt	Dynamic feedback queues
Lottery	./simulator --scheduler lottery --input tasks.txt	Randomized selection
CFS	./simulator --scheduler cfs --input tasks.txt	Completely Fair Scheduler
EDF	./simulator --scheduler edf --input tasks.txt	Preemptive, uses deadlines
Random processes	./simulator --scheduler rr --random	Generates 10 random processes
Random custom count	./simulator --scheduler rr --random --num 20	Generates 20 random processes
Log output	./simulator --scheduler rr --random --output log.txt	Logs metrics & Gantt chart