Priority management for concurrent execution of real-time and on-line transactions

This paper presents priority management methods for concurrent execution of real-time transactions with timing constraints and on-line transactions without timing constraints in a real-time database system (RTDBS). The aim of this study is the meeting of deadlines of real-time transactions and shortening the response time of on-line transactions at the same time. The proposed methods are Simple Mix, Biased Mix, and Balanced Mix, each of which differs in its strategy for assigning priorities to on-line transactions. Simulation results show that Balanced Mix, which determines priorities dynamically according to the slack of real-time transactions, can shorten the response time of on-line transactions while keeping the deadline-missing ratio of real-time transactions low.