Performance Evaluation of New Joint EDF-RM Scheduling Algorithm for Real Time Distributed System

In Real Time System, the achievement of deadline is the main target of every scheduling algorithm. Earliest Deadline First (EDF), Rate Monotonic (RM), and least Laxity First are some renowned algorithms that work well in their own context. As we know, there is a very common problem Domino's effect in EDF that is generated due to overloading condition (EDF is not working well in overloading situation). Similarly, performance of RM is degraded in underloading condition. We can say that both algorithms are complements of each other. Deadline missing in both events happens because of their utilization bounding strategy. Therefore, in this paper we are proposing a new scheduling algorithm that carries through the drawback of both existing algorithms. Joint EDF-RM scheduling algorithm is implemented in global scheduler that permits task migration mechanism in between processors in the system. In order to check the improved behavior of proposed algorithm we perform simulation. Results are achieved and evaluated in terms of Success Ratio (SR), Average CPU Utilization (ECU), Failure Ratio (FR), and Maximum Tardiness parameters. In the end, the results are compared with the existing (EDF, RM, and D_R_EDF) algorithms. It has been shown that the proposed algorithm performs better during overloading condition as well in underloading condition. 1. Introduction and Motivation Real Time Distributed System is a distributed system with real time properties. We can say that RTDS is a combination of RTS and distributed system (Figure 1). Properties of real time tasks are applied on the distributed system or concept of a distributed system is implemented on RTS. The following is the first appearance of two main components of RTDS. Figure 1: Real time distributed system. 1.1. Real Time System (RTS) RTS is a system in which execution of tasks has some time restrictions (deadline) [1–3]. Based on the execution of real time task RTS falls into the following categories.(i)Hard RTS. Task execution by assigning deadline is restrictive. Missing deadline will produce incurable results for the entire system [4].(ii)Soft RTS. Although missing deadline is not enviable in RTS, but in soft RTS tasks could miss some deadline that will not affect the working of system [5].(iii)Firm RTS. If tasks complete their execution before the deadline, they gain more rewards [4, 6]. It is a special type of soft RTS. EDF, RM, and Least Laxity First are some basic scheduling algorithms that execute real time tasks on the basis of their deadline, interarrival period, tardiness, and so forth. Every