Capacity sharing for overrun control

In this paper, we present a general scheduling methodology for managing overruns in a real-time environment, where tasks may have different criticality and flexible timing constraints. The proposed method achieves isolation among tasks through a resource reservation mechanism which bounds the effects of task interference, but also performs efficient reclaiming of the unused computation times to relax the utilization constraints imposed by isolation. The enhancements achieved by the proposed approach resulted 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 to be taken into account in the schedulability analysis. However, it resulted to be negligible in most practical cases.