A Method for Satisfying Asynchronous and Periodic Timing Requirements in Real-Time Embedded Systems

A method for satisfying asynchronous and periodic timing requirements in real-time embedded systems is presented. A guiding principle for this method is that it should exploit to a maximum extent any knowledge about system processes´ characteristics that is available both before run-time and during run-time. The method consists of two phases: a pre-run-time phase and a run-time phase. In the pre-run-time phase, some of the asynchronous processes will be converted into new periodic processes while processor capacity will be reserved for all the remaining asynchronous processes. With the use of an optimal scheduling algorithm, the schedulability of the set of the new and original periodic processes will be determined, while the schedulability of all the asynchronous processes will be verified by checking their worst-case response times. In the run-time phase, asynchronous processes are scheduled for execution while guaranteeing that all the processes that have already been scheduled in the pre-run-time phase will always meet their deadlines.