Graph Transformations and Derivation of Scheduling Constraints Applied to the Mapping of Real-Time Distributed Applications

Abstract

Synchronous Data-Flow as a deterministic variation of Khan Process Networks is a good model for distributed applications that allows for verification of the properties of the applications both at the design level and at run-time. Real-Time extensions exist which allow to specify Real-Time clocks for some of the processes in the graph. With the addition of Real-Time clocks, the behavior of the complete system can be easily differentiated from a nominal Real-Time mode where all the required data for processing is available when a clock tick occurs, and an error mode can be triggered when the condition is not met. Our contribution in this paper is –first– to show a set of graph transformations that allow to account for the execution and communication time on a real platform while at the same time maximizing the parallelism of execution and –second– on top of these transformations to provide the execution constraints as a linear program that must be met at run-time to guarantee the real-time requirements. It is illustrated on a subset of a real-life automotive example.