DESIGN AND IMPLEMENTATION OF A MODIFIED MEDIAN ROUND ROBIN ALGORITHM (DIMMRRA (STATISTICS PROJECT TOPICS AND MATERIALS)
Abstract
Central Processing Unit (CPU) scheduling involves a careful examination of pending processes to determine the most efficient way to service the requests. Several scheduling algorithms have been designed to arrange accesses to computer resources efficiently. Round robin scheduling algorithm (RRSA) is an attractive algorithm but suffers from the problem of time quantum determination. In the classical round robin algorithm, quantum time is fixed throughout the scheduling process. This static nature made it very difficult to optimize the algorithm. The only solution to this problem is to provide a quantum time that changes dynamically during execution. Major challenges of dynamic round robin schedulers reported in the literature are: they do not include Average Response Time as a criterion for comparison and they do not bother much on preempting processes with negligible completion time after executing for a given time quantum leading to an increase in the number of context switches. This research proposed an algorithm, the Modified Median Round Robin (MMRRA), with a dynamic time quantum aimed at reducing the overhead of the RRSA. The proposed algorithm was implemented and evaluated against the following five algorithms in the literature: Improved Round Robin (IRR), Improved Mean Round Robin with Shortest Job First (IMRRSJF), Dynamic Round Robin with Controlled Preemption (DRRCP), Half Life Variable Quantum Time RR (HLVQTRR) and CLASSICAL RR. Which in turns, proved to perform better in terms of AWT, ATAT and NCS. But, in terms of ART, HLVQTRR has the best result but still the result for MMRRA was not bad.
CHAPTER ONE:
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Process scheduling algorithm has been an interesting field of study in Operating Systems. Scheduling is a key concept in computer multitasking, multiprocessing and real-time operating system designs.
The operating system uses some sort of scheduling techniques to allocate resources to processes in the ready queue. Scheduling refers to the way processes are assigned to run on available Central Processing Unit (CPU). Certain CPU scheduling techniques or algorithms have been developed. The overall goal of these algorithms is to: maximize CPU utilization, reduce average waiting time and average turnaround time, reduce the number of context switching, increase throughput and try as much as possible to be fair to all processes.
