An Algorithm for Scheduling Aperiodic Real-Time Tasks on a Static Schedule

In many real-time systems, there are not only periodic real-time tasks, but also aperiodic real-time tasks arising from arbitrary critical events. In this paper, we propose an algorithm (SATSS, Schedule Aperiodic Tasks on a Static Schedule) scheduling both periodic real-time tasks and aperiodic real-time tasks. This algorithm first produces a schedule which consists of only periodic tasks before the system is started and schedules aperiodic tasks on the static schedule on run time. It can guarantee all accepted tasks´ deadlines by testing the schedulability of aperiodic tasks in a busy period consisting of not only the running tasks but also the periodic tasks in future. Experimental results show that the algorithm is effective.