Task Migration with EDF-RM Scheduling Algorithms in Distributed System Rashmi Sharma Department of CSE and ICT Jaypee University of Information Technology, Waknaghat, Solan-173234, Himachal Pradesh, India rashmi.nov30@gmail.com Nitin Department of CSE and ICT Jaypee University of Information Technology, Waknaghat, Solan-173234, Himachal Pradesh, India delnitin@ieee.org Abstract—Earliest deadline first and Rate Monotonic are the two well-known scheduling algorithms to meet the deadlines for task in RTS. For single processor, these tasks work well but for more than one node, overloading in utilization usually creates problem. Task migration and duplication are those two concepts that balance the load of distributed system due to which overloading problem has been resolved. This paper explains the processing of task migration with EDF-RM (simultaneously) scheduling algorithm by using Global Scheduling. Keywords- Real Time Distributed System (RTDS); Task Migration; Earliest Deadline First (EDF); Rate Monotonic (RM). I. INTRODUCTION AND MOTIVATION Management of real time tasks is somewhat uncertain in distributed system. In real time uniprocessor system after crossing the limit of utilization tasks start missing their deadline. However, in RTDS, mostly tasks distribute to other processors of the system and parallel execution takes place. Therefore, the rejection is overruled. The balancing of distributed tasks sustain by task migration or duplication concept. For the maintenance of proper resource utilization, task migration and duplication are the favorable solutions. The system under consideration is a Real Time Distributed System (RTDS), which is by definition “A Distributed System is having Real Time Properties”. The architecture of processors in distributed system can be homogenous as well as heterogeneous. In homogenous system processors share the similar architecture and dissimilar in heterogeneous. Here we are using homogenous system [1]. In Real time system, every task has a deadline (by that time task should execute). For scheduling of real time tasks, Rate Monotonic and Earliest deadline first are two well-known scheduling algorithms under which execution of tasks based on its period of arrival or deadline as well. RM algorithm works with Static Priority Scheduling (offline tasks) and EDF algorithm is with Dynamic Priority Scheduling (online tasks). The arrival of tasks in a particular system can be periodic, aperiodic or sporadic. Mostly systems set aside the arrival of tasks periodically because the period of task arrival is fixed and these tasks are able to meet their respective deadline (relative deadline) [2]. Every scheduling algorithm has its own merits and demerits, like EDF assign priority based on deadline of the task and working well for single processor in underloading condition but working inefficiently in overloaded case [3]. RM is a static algorithm and priorities based on periods but it is not as capable as dynamic algorithms for underloaded conditions [4] but performing well in overloaded as compared to Dynamic algorithms. In Distributed System, this overloaded and underloaded problem has been balanced by using the task migration method. For scheduling of periodic task systems on Distributed System there have been two approaches: partitioning and global scheduling. In global scheduling, single priority ordered queue of eligible tasks have maintained and scheduler selects the highest priority task for execution. However, in partitioning scheduling, each task is assigned to single processor and processors are scheduled independently [5]. Out of these two schedulers, previous one requires task migration and in last task migration is prohibited [6]. Load balancing (in RTDS) is handled by using task migration with optimal scheduler and for the execution of real time tasks either RM or EDF algorithms are used according to the demand of the system. This paper explains RM and EDF together with migration. The rest of the paper organizes as follows: Section II explains the real time scheduling algorithms (RM and EDF) and migration in distributed system, Section III describes the proposed algorithm of RM and EDF (with Migration) with examples. Further Conclusion and future work will be discussed. II. PRELIMINARIES AND BACKGROUND The major approach of scheduling multiprocessors real time tasks is partitioned scheduler in which only one task can execute at a time on particular processor; a bin-packing problem is presented here in the same. On the other side, global scheduling is another option of partitioned scheduling which maintains a global task queue from which tasks are sent out to any vacant processor according to a global priority scheme [7]. In terms of task migration, we can say that in partitioned scheduler it is not permitted whereas in global scheduling migration can be done. Load balancing in distributed system is necessary which is achieved by the use of task migration concept. Hence, in our system we are using global scheduler for scheduling the tasks of homogenous RTDS. The arrival of real time tasks is periodic in nature because the execution of one task on or before the arrival of next task is necessary otherwise, there will be a chance of missing the deadline. Real time periodic tasks have following parameters: 2012 International Conference on Advances in Computing and Communications 978-0-7695-4723-7/12 $26.00 © 2012 IEEE DOI 10.1109/ICACC.2012.42 182 2012 International Conference on Advances in Computing and Communications 978-0-7695-4723-7/12 $26.00 © 2012 IEEE DOI 10.1109/ICACC.2012.42 182