Global Semi-Fixed-Priority Scheduling on Multiprocessors

Current real-time systems such as robots have multiprocessors and the number of processors tends to be increased. In order to achieve these real-time systems, global real-time scheduling has been required. Many real-time scheduling algorithms are usually based on Liu and Layland's model. Compared to Liu and Layland's model, the imprecise computation model is one of the techniques to overcome the gap between theory and practice. Semi-fixed-priority scheduling is part-level fixed-priority scheduling in the extended imprecise computation model, which has a second mandatory part to terminate an optional part. Unfortunately, current semi-fixed-priority scheduling is only adapted to uniprocessors. This paper presents a global semi-fixed-priority scheduling algorithm, called Global Rate Monotonic with Wind-up Part (G-RMWP). G-RMWP calculates the optional deadline, the termination time of each optional part, by Response Time Analysis for Global Rate Monotonic (G-RM). The schedulability analysis shows that one task set is schedulable by G-RMWP if the task set is schedulable by G-RM. Simulation results show that G-RMWP has higher schedulability than G-RM.