Capacity Sharing for Overrun Control

Marco Caccamo, Giorgio C. Buttazzo, Lui Sha

Abstract: Presents a general scheduling methodology for managing overruns in a real-time environment, where tasks may have different criticalities and flexible timing constraints. The proposed method achieves isolation among tasks through a resource reservation mechanism which bounds the effects of task interference but which also performs efficient reclamation of the unused computation times in order to relax the utilization constraints imposed by isolation. The enhancements achieved by the proposed approach were found to be very effective with respect to classical reservation schemes. The performance has been evaluated by implementing the algorithm on a real-time kernel. The runtime overhead introduced by the scheduling mechanism has also been investigated with specific experiments, in order for this to be taken into account in the schedulability analysis. However, this overhead was found to be negligible in most practical cases.