Dynamic Reconfiguration for Adaptive Multiversion Real-Time Systems

Modern real-time systems must be designed to be highly adaptable, reacting to aperiodic events in a predictable manner and exhibiting graceful degradation in overload scenarios whenever needed. In this context, it is useful to structure the system as a set of multiversion tasks. Task versions can be modeled to implement services with various levels of quality. In overload scenarios, for instance, a lower quality service may be scheduled for execution keeping the system correctness and providing graceful degradation. The goal of the reconfiguration mechanism is to select the versions of tasks that lead to the maximum benefit for the system at runtime. In this paper, we provide a schedulability condition based on which we derive an optimal pseudo-polynomial solution for this problem. Then, a faster approximation solution is described. Results from simulation indicate the effectiveness of the proposed approach.