Scheduling algorithms based on weakly hard real-time constraints

The problem of scheduling weakly hard real-time tasks is addressed in this paper. The paper first analyzes the characters of μ-pattern and weakly hard real-time constraints, then, presents two scheduling algorithms, Meet Any Algorithm and Meet Row Algorithm, for weakly hard real-time systems. Different from traditional algorithms used to guarantee deadlines, Meet Any Algorithm and Meet Row Algorithm can guarantee both deadlines and constraints. Meet Any Algorithm and Meet Row Algorithm try to find out the probabilities of tasks breaking constraints and increase task’s priority in advance, but not till the last moment. Simulation results show that these two algorithms are better than other scheduling algorithms dealing with constraints and can largely decrease worst-case computation time of real-time tasks. TU Gang received his M.S. degree in computer science from Huazhong University of Science and Technology (HUST) in 2001. Now he is a Ph.D. candidate in Institute of Computer Science, HUST. His research interests are real-time scheduling algorithms and embedded real-time systems. YANG FuMin is a professor of Huazhong University of Science and Technology. He received his M.S. degree in computer science from HUST in 1989. Currently, he is the head of Embedded Real-Time Operating System Lab of HUST. His research interests cover real-time systems, embedded systems and DBMS. LU YanSheng is a professor and Ph.D. supervisor of Huazhong University of Science and Technology. He received his M.S. degree in computer science from HUST in 1985. Currently, he is the head of the Institute of Software of HUST. His research interests cover real-time systems, real-time DBMS and data mining.