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.