Code-Inherent Traffic Shaping for Hard Real-Time Systems

Modern hard real-time systems evolved from isolated single-core architectures to complex multi-core architectures which are often connected in a distributed manner. With the increasing influence of interconnections in hard real-time systems, the access behavior to shared resources of single tasks or cores becomes a crucial factor for the system’s overall worst-case timing properties. Traffic shaping is a powerful technique to decrease contention in a network and deliver guarantees on network streams. In this paper we present a novel approach to automatically integrate a traffic shaping behavior into the code of a program for different traffic shaping profiles while being as least invasive as possible. As this approach is solely depending on modifying programs on a code-level, it does not rely on any additional hardware or operating system-based functions. We show how different traffic shaping profiles can be implemented into programs using a greedy heuristic and an evolutionary algorithm, as well as their influences on the modified programs. It is demonstrated that the presented approaches can be used to decrease worst-case execution times in multi-core systems and lower buffer requirements in distributed systems.