Multitask implementation of synchronous reactive models with Earliest Deadline First scheduling

Model-based development of embedded systems enables early verification of functionality, reduces turnaround times and testing efforts, and allows to cope with the increasing complexity of these systems. Software implementations can be automatically generated from models, reducing the possibility of injected errors upon condition that the generated code is correct, efficient, and schedulable on the selected platform. When multitask implementations are generated for multirate systems, a time-feasible (schedulable) implementation may be possible only with additional functional delays on selected communication links. These delays may degrade the performance of feedback controls and require additional memory for buffering the channel state. In this paper, we present a branch-and-bound procedure and a heuristic algorithm to minimize the use of functional delays in the synthesis of model implementations on platforms scheduled by EDF (Earliest Deadline First). The proposed heuristic is shown to find close-to-optimal solutions, while executing much faster than (possibly exhaustive) branch-and-bound.