Handling Non-periodic Events Together with Complex Constrained Tasks in Distributed Real-time Systems

In this paper we show how off-line scheduling and fixed priority scheduling (FPS) can be combined to get the advantages of both the capability to cope with complex timing constraints while providing run-time flexibility. We present a method to take advantage of the flexibility provided by FPS while guaranteeing complex constraint satisfaction on periodic tasks. We provide mechanisms to include FPS servers to our previous work, to handle non-periodic events, while still fulfilling the original complex constraints on the periodic tasks. In some cases, e.g., when the complex constraints can not be expressed directly by FPS, we split tasks into instances (artifacts) to obtain a new task set with consistent FPS attributes. Our method is optimal in the sense that it keeps the number of artifacts minimized.