In the modern era of technology, Multiprogramming (Multi-Tasking) became a major issue for a system because every user wants to run many applications at a time. In time shared-environment, system resources distributed among the available application in main memory. Improper uses of system resources may degrade the system performance, so we need proper utilization of resources. Hence scheduling is a mechanism by which we can utilize the system resources efficiently. We have many CPU scheduling algorithms but in contrast to time shared environment, round robin is the best choice. In this algorithm, processes get equal opportunity to execute its task. System performance solely depends on scheduling algorithm and round robin performance only depends on the choice of time quantum. Thus selecting the optimal time quantum is the main problem in this algorithm because if it very small then CPU will spend lots of time context switches which will degrade the system performance and if it is too large then response time processes will be increased which cannot be tolerated in time shared environment. Therefore this shows an optimal approach for selecting time quantum and comparison shows that the OASRR algorithm performance better than all variants of round robin algorithms and this algorithm having minimum avg. turnaround time, waiting time and less no. of context switches.

CPU Scheduling, Round Robin, Time Quantum, Waiting Time, Turnaround Time, Context Switches

[1] Saroj hiranwal and D.r. K.C.Roy"Adaptive Round Robin Scheduling using Shortest Burst Approach Based on Smart Time Slice”.volume 2,issue 3.
[2] Sanjay Kumar Panda and Saurav Kumar Bhoi, “An Effective Round Robin Algorithm using Min-Max Dispersion Measure” ISSN: 0975-3397, Vol. 4 No. 01, January 2012.
[3] "Tannenbaum, A.S., 2008" Modern Operating Systems. 3rd Edn., Prentice Hall, ISBN: 13:9780136006633, pp: 1104.
[4] “Silberschatz, A., P.B. Galvin and G. Gagne, 2008”Operating Systems Concepts. 7th Edn., John Wiley and Sons, USA., ISBN: 13: 978-0471694663, pp: 944.
[5] H. S. Behera, Rakesh Mohanty, Sabyasachi Sahu and Sourav Kumar Bhoi.”Comparative performance analysis of multi-dynamic time quantum round robin (mdtqrr) algorithm with arrival time”, ISSN: 0976-5166, Vol. 2, No. 2, Apr-May 2011.
[6] “Rakesh Mohanty, H.S. Behera and et. al, Design and Performance Evaluation of a new proposed Shortest Remaining Burst Round Robin(SRBRR) scheduling algorithm, Proceedings of the International Symposium on Computer Engineering and Technology(ISCET), March 2010.
[7] "Yaashuwanth .C & R. Ramesh" Intelligent time slice for round robin in a real-time operating system, IJRRAS 2 (2), February 2010
[8] Milan Milinkovic, “Operating Systems Concepts and Design”, McGraw-Computer Science Series, second edition.
[9] A. Dhore “Operating Systems”, Technical Publications.
[10] M. Dietel, “Operating Systems”, Pearson Education, Second Edition.
[11] “Real Time Task Scheduling “, NPTEL, IIT Kharagpur
P. Balakrishna Prasad, “Operating Systems” Second Edition