Incremental reconfiguration and load adjustment in adaptive real time systems

We provide a framework for discussing how to adjust load in order to handle periodic processes whose timing parameters vary with time. The schedulability of adjustable periodic processes by a preemptive fixed priority scheduler is formulated in terms of a configuration selection problem for which a PTIME solution is shown. When the list of allowable configurations is implicitly given by a set of scalable periodic processes, the corresponding period assignment problem is shown to be NP-Complete. We present an approximation algorithm for the period assignment problem for which we show some encouraging experimental results