cpu-scheduling

Overview

This project implements a CPU Scheduling Simulator in C/C++ for the Operating Systems course at Alexandria University – Faculty of Engineering.

The program analyzes and visualizes different CPU scheduling algorithms. It reads process information from stdin, simulates the scheduling policy, and prints either:

• Trace output showing how processes execute over time, or

• Statistics output summarizing scheduling performance.

The program follows the exact input/output format required for automatic grading.

Implemented Scheduling Algorithms

The simulator supports the following policies:

- First Come First Serve (FCFS)
- Round Robin (RR)
- Shortest Process Next (SPN)
- Shortest Remaining Time (SRT)
- Highest Response Ratio Next (HRRN)
- Feedback Queue (FB-1)
- Feedback Queue (FB-2i)
- Aging

Notes

• Round Robin requires a quantum parameter q.
• Aging also uses a quantum parameter.

Input Format

The program reads input from stdin.

Line 1

• Mode of execution:traceorstats

• trace → visual timeline of process execution

• stats → scheduling statistics

Line 2

• Comma-separated scheduling policies.

Example:

1,2-4,3

Meaning:

• FCFS
• Round Robin (q=4)
• SPN

Line 3

Last simulation time

Example: 20

Line 4

Number of processes

Example: 3

Line 5+

Process description

For algorithms 1–7:

ProcessName,ArrivalTime,ServiceTime

Example:

A,0,3
B,2,6
C,4,4

For Aging (Algorithm 8):

ProcessName,ArrivalTime,Priority

Output Format

The output is printed to stdout.

Trace Mode :

* → process is executing

. → process is waiting in the ready queue

Example:

time → 0123456789
A     ***.....
B     ..****..
C     ....****

Stats Mode

Displays scheduling statistics such as:

• Waiting time
• Turnaround time
• Completion time

The format must exactly match the provided test cases.

Compilation

A Makefile is provided.

Compile the program using: make

This will generate the executable: scheduling

Running the Program

Use input redirection:

./scheduling < input.txt

or

cat input.txt | ./scheduling

Testing With Provided Test Cases

You can compare your output with the expected output using:

cat 01a-input.txt | ./scheduling | diff 01a-output.txt -

If there is no output from diff, the test case passed.

Docker

A Dockerfile is provided to build a lightweight image for the project.

Build Image docker build -t cpu-scheduler .

Run Container docker run -i cpu-scheduler < input.txt

Project Structure

.
├── scheduling.cpp
├── scheduling.h
├── Makefile
├── Dockerfile
├── README.md
├── run_tests.sh
└── testcases/