Joint Task and Flow Scheduling for Time-Triggered and Strict-Priority Networks

Abstract

Compliance with the end-to-end latency of tasks and flows is a safety-relevant constraint in real-time systems. Especially when tasks and flows are interconnected by data dependencies in so-called Cause-Effect Chains, the adherence to end-to-end restrictions becomes even more complex. In our previous work, we proposed the incremental algorithm ITANS, which presents a solution for the joint scheduling of tasks and flows organized in Cause-Effect-Chains in communication networks applying the IEEE 802.1Qbv Time-Aware Shaper. In this work, we extend the approach to communication networks using the scheduling method Strict Priority (SP). The determination of the worst-case transmission time (WCTT) of flows is an essential part of ITANS. To derive the WCTT of flows in SP-based networks, we use the mathematical framework Network Calculus (NC) combining existing analyses to derive the least pessimistic delay guarantees for network flows. The evaluations show that the extension of ITANS can achieve a high success rate and a low runtime on average in systems with Gigabit Ethernet and communication networks that use SP.