Operating System Project Simulation and Comparison of Short-Term-Scheduler Algorithms Student: Fasheng Qiu Instructor: Bernard Chen 04/19/2007

Introduction  Scheduling is a fundamental operating-system function. CPU scheduling is central to operating system design.  There are many algorithms of CPU scheduling. First-Come, First-Served Scheduling Shortest-Job-First Scheduling (preemptive or non-preemptive) Round-Robin Scheduling  An intuitive understanding of the performance and use cases of various CPU scheduling algorithms is important for the algorithm designer/learner and operating-system designer. Hence, developing an easy-to-use and easy-to-understand simulation software makes sense, for either the designer or the learner.

Objectives and Design  Achieve a user-friendly GUI-based system, where the user can easily simulate and compare different algorithms in any given size of testing samples ( processes ).  Currently, the system was implemented and has the following functionalities: Simulation (for two algorithms) Parameters setting, global or individual Simulate algorithms, two of them Comparison (for all algorithms) Show results, textual or graphic

Parameters Setting  Global parameters Number of processes Max process time  Individual parameters Quantum Context switch penalty

Simulation (two algorithms)  Show dynamic progress  Also # of started/completed jobs

Comparison (all algorithms)  All four algorithms are chosen: First come, First served Shortest Job First Preemptive Shortest Job First Round-Robin  Processes and their process time are randomly generated, each controlled by a maximum value  Three steps involved: Generating processes Generating algorithms Preparing timers Updating user interface

Comparison  Textual show ProcessID, Length and Response & Tounaround times (the criteria in comparison of algorithms)  Graphic show, can prove:  FCFS: The average of waiting time in this policy is usually quite long  SJF is optimal: Gives minimum average waiting time for a given set of processes  RR: Typically, higher average turnaround than SJF, but better response

Conclusion and Future work  Conclusion A simulation and comparison application for four cpu scheduling algorithms is provided, including two subsystems: simulation and comparison  Testing more algorithms Such as multi-level scheduling algorithms

The End That’s It Thanks!