混合事务的ERtTDF调度算法及可调度性分析

ERtTDF Scheduling Algorithm and Scheduling Analysis for Hybrid Real-time Transactions

在实时数据库及数据处理系统中,针对周期性实时事务,应用经典的EDF等调度算法对其可以得到可行的调度;而对于混合实时事务-事务的时间性质是混合的,经典EDF不太适用。文中扩展EDF为最早实时事务截止期优先-ERtTDF(EarliestReal-timeTransactionDeadlineFirst),它可以有效地调度混合事务。文中给出了其可调度条件和时间需求条件,并把时间需求条件扩展到时限小于周期以及引入资源共享控制等方面,最后给出了集成调度实时、非实时以及混合事务的系统框架。通过性能比较,可以得到ERtTDF算法处理上面事务模型时性能较经典EDF更优。

With regard to the periodic real-time transactions,one could apply the classic algorithm-Earliest Deadline First to get a feasible scheduling in the field of real-time database.However,it is not suitable for the hybrid real-time transactions which may include both the real-time part and non-real-time part.In this paper we have developed an algorithm which is named as Earliest Real-time Transaction Deadline First.The hybrid transactions could be scheduled under the algorithm effectively.This paper presents the schedulability conditions and time demand conditions first,then allows the transactions whose deadline is less than the period,and also brings in the resource sharing protocol.In the last,an integrated scheduling frame is demonstrated to cope with the sets of real-time,non-real-time and hybrid transactions.For the model mentioned in the paper, ERtTDF algorithm is better in performance.