A simple scheduler simulator for Operating Systems

Platform: Linux Language: C/C++

Introduction

A CPU scheduler determines an order for the execution of its scheduled processes; it decides which process will run according to a certain data structure that keeps track of the processes in the system and their status.

A process after creation has one of the three states: Running, Ready, Blocked (doing I/O , using other resources than CPU or waiting on unavailable resource).

A bad scheduler will make a very bad Operating System, so a scheduler should be as much optimized as possible in terms of memory and time usage.

System Description

Consider a Computer with CPU and infinite memory, the scheduler with its complementary components as the following

Part 1: Process generator (Objective: For simulation & IPC)

Code file: processGenerator.cpp

Process generator: responsible for

• Reading the input files (check Part 5)
• Ask the user about the chosen scheduling Algorithm and its parameters if exists.
• Initiate and create Scheduler and Clock processes.
• Creating a data structure for process and provide it with its parameters
• Send the information to the scheduler at the appropriate time (only when a process arrives) so that it will be put it in its turn.
• At the end it Clear IPC Resources.

Part 2: Clock (Objective: For simulation & IPC)

Code file: clk.cpp

The clock module is used to emulate a integer time clock headers.h contains clk functions. It should be included anywhere the clock functions are used. To get time call, use:
getClk();

Part 3 : Scheduler (Objective: OS Design, IPC)

Code file: scheduler.cpp

The scheduler is the core of this project, it should keep track of the processes and their states and it decides – based on the used algorithm - which process will run & for how long.

The scheduler consists of mainly three Algorithms:

1. non-preemptive HPF
2. Shortest Remaining time Next
3. Round Robin

The scheduling algorithm only works on the processes in the ready queue; a process that already arrived.

The Scheduler should be able to

• Start a new process according to the scheduling algorithm.(Fork it and give its parameters)
• Switch between two processes according to the scheduling algorithm. (Stop the old process and save its state and start/resume another one)
• At anytime, it should have a process control Block that keeps track of the state of the processes in the system (running/waiting/execution time/ remaining time/ waiting time/ ...etc)
• If the scheduler is notified that a process finished, it delete its data.

When a process finishes it should notify the scheduler on termination, the scheduler doesn't terminate the process.

For each algorithm, the code reports:

• CPU utilization.
• average weighted turnaround time.
• average waiting time.
• standard deviation for average weighted turnaround time.

The Scheduler Generates two files: (check Part 5)

• Scheduler.log
• Scheduler.perf

Part 4 : process (Objectives: simulation, IPC)

Code file: process.cpp

The process should act as if runs in the execution time, the process communicate with clock functions.

Part 5 : Input / output (Objectives: simulation, evaluation OS Design)

Input:

Output:

How to use?

• Clone this repository.
• To compile the project, write on linux terminal
  make
• To run the project, write on linux terminal
  make run