Optimal Scheduling of Precedence-constrained Task Graphs on Heterogeneous Distributed Systems with Shared Buses

Real-time applications in today's distributed cyber-physical control systems are often represented as Precedence-constrained Task Graphs (PTGs) and increasingly implemented on heterogeneous platforms to cater to their high performance demands. Optimal scheduling solutions for such systems can provide advantages in terms of performance, reliability, cost etc. However, existing research works dealing with the optimal scheduling of PTGs, typically assume platforms consisting of homogeneous processing elements which interact through a fully connected network of homogeneous communication channels. In this work, we propose an Integer Linear Programming based optimal solution strategy for scheduling PTGs executing on a distributed platform composed of heterogeneous processing elements and inter-connected through a set of heterogeneous shared buses. Through the real-world case study of an automotive cruise controller, we generate an optimal schedule using our proposed scheme in order to demonstrate its generic applicability. Conducted experiments on benchmark PTGs reveal the practical efficacy of our scheme.