Priority Scheduling (Preemptive + Non-preemptive)

A small Python simulator for Priority CPU Scheduling supporting both:

• Non-preemptive priority scheduling: once a process starts, it runs until it finishes.
• Preemptive priority scheduling: a newly-arrived higher-priority process can interrupt the currently running process.

Priority rule: lower number = higher priority (e.g., priority 1 runs before 2).

Tie-breaker: FCFS (first-come, first-served) for equal priority.

Project Structure

Priority-Scheduling/
  src/
    __init__.py
    process.py
    simulator.py

• src/process.py defines the Process and TimelineSegment data models.
• src/simulator.py contains the simulate(...) function and simulation config/result types.

Requirements

• Python 3.10+

How to Run

Download the project from this github reposiotory.

Open the project, and then open a terminal in the root folder.

navigate to

cd src

execute:

python -m src.simulator

Note: using -m matters because src/simulator.py uses relative imports (e.g., from .process import Process).

Input Model

Each process has:

• pid: process id (string)
• arrival_time: when the process becomes ready (int time units)
• burst_time: CPU time needed (int time units)
• priority: smaller value means higher priority

Example:

Process(pid="P2", arrival_time=1, burst_time=4, priority=1)

Output

The simulator returns a SimulationResult:

• TimelineSegment(start, end, label)
• label is usually a PID like "P1" or "IDLE" (or "CS" if context switching cost is enabled)

Example segment meaning:

• TimelineSegment(start=1, end=5, label='P2') means P2 ran from time 1 up to (not including) time 5.