CPU Scheduler Simulator

CSC-264 · Semester IV · Operating Systems

intermediate30 minAvailable

CPU Scheduler

Compare algorithms on a Gantt chart with waiting & turnaround times.

Process table

PID	Arrival	Burst	Pri.

Presets

Configure the processes, pick an algorithm, and press Run to draw the Gantt chart.

Lab brief

Objective

Simulate CPU scheduling algorithms on the same set of processes and compare average waiting and turnaround times.

Theory & concepts

The CPU scheduler decides which ready process runs next. FCFS runs processes in arrival order; SJF picks the shortest next burst; Round Robin gives each process a fixed time quantum in turn. Each produces different average waiting time — and Round Robin can be tuned by changing the quantum.

Rendering diagram…

The CPU scheduling cycle and the three classic policies

Algorithm	Idea	Strengths	Weaknesses
FCFS	First come, first served	Simple, fair by arrival	Convoy effect
SJF	Shortest job first	Minimal waiting time	Requires future knowledge
Round Robin	Time-shared quantum	Responsive for interactive use	Quantum tuning needed

Prerequisites

Lesson: Scheduling criteria and algorithms

Instructions

1Add processes with arrival time and burst time (or use the sample set).
2Select an algorithm and run the simulation.
3Read the Gantt chart of execution order.
4Compare average waiting and turnaround times across algorithms.

Tasks

Run FCFS
Use the sample set and record average waiting time.
Run SJF and Round Robin
Repeat with the same set; rank the algorithms.
Vary the quantum
Change the Round Robin quantum from 2 to 4 and observe the effect.
Explain the trade-off
Why can SJF starve long jobs? Why does Round Robin add overhead?

Self-check

Gantt charts match hand-computed schedules for the sample set.
Average waiting times are correct.
The student explains the effect of the time quantum.

Environment

process editorGantt chartmetrics panelmultiple algorithms