CPU Scheduling Simulator

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Repository: https://github.com/walshyaw/CPU-Scheduler

This project simulates four CPU scheduling algorithms (FCFS, Priority, SRTF, and Round Robin) written in C++. It reads process data from an input file and outputs per-time-unit PCB traces, Gantt charts, and average scheduling metrics for each algorithm. The simulator covers both non-preemptive and preemptive scheduling strategies for side-by-side comparison.

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How to Compile

g++ src/*.cpp -o scheduler

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How to Run

./scheduler

The program reads from input.txt and writes output to:

• output_fcfs.txt
• output_srtf.txt
• output_priority.txt
• output_rr.txt

Each output file contains a full per-time-unit PCB trace, a Gantt chart, and average scheduling metrics (wait time, turnaround time, response time).

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Input Format

The input file (input.txt) follows this format:

PID    Arrival    Burst    Priority
P1     0          5        2
P2     1          3        1
P3     2          1        3
P4     3          2        2

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Project Structure

project1_Walsh_1867402/
├── Part_A/
│   └── manual_analysis.pdf
└── Part_B/
    ├── src/
    │   ├── main.cpp
    │   ├── pcb.h / pcb.cpp
    │   ├── queue.h / queue.cpp
    │   ├── loadInput.h / loadInput.cpp
    │   ├── fcfs.h / fcfs.cpp
    │   ├── priority.h / priority.cpp
    │   ├── srtf.h / srtf.cpp
    │   ├── rr.h / rr.cpp
    │   └── outputGantt.h / outputGantt.cpp
    ├── input.txt
    ├── output_fcfs.txt
    ├── output_srtf.txt
    ├── output_priority.txt
    ├── output_rr.txt
    ├── README.md
    └── AI_USAGE.txt

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Algorithms Implemented

Algorithm	Type	Selection Criterion
FCFS	Non-preemptive	Arrival order
Priority	Non-preemptive	Lowest priority number (highest priority)
SRTF	Preemptive (event-based)	Shortest remaining time
Round Robin	Preemptive (time-based)	FIFO with time quantum

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Statistics Computed

For each algorithm, the following are calculated per process and averaged:

• Waiting Time: completion_time - arrival_time - burst_time
• Turnaround Time: completion_time - arrival_time
• Response Time: start_time - arrival_time