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:

non-preemptive HPF
Shortest Remaining time Next
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.

MichaelKMalak/OS-Scheduler