Flexible TDM-based resource management in on-chip networks
Adam Kostrzewa, Selma Saidi, Leonardo Luiz Ecco, Rolf Ernst · 2015
Time-division multiplexing (TDM) is the commonly used and well established solution to the problem of sharing resources in real-time Networks-on-Chip (NoCs). TDM timing is well predictable, simplifies worst-case analysis and is easy to implement. However, it introduces a constant, periodic and non-work-conserving resource sharing scheme. This challenges resource efficiency whenever the applications expose dynamics in execution time, communication volume and whenever the system is not highly loaded. In this work, we present a flexible TDM approach for NoCs where the TDM cycle adapts dynamically to the current load of data streams accessing the network. This is performed using a global arbitration layer managed by a scheduling unit called Resource Manager (RM) and a dedicated protocol. We present a formal worst-case timing analysis of this approach which allows to provide guarantees to all streams using the NoC. Finally, we demonstrate that our mechanism not only exhibits higher average performance but, even more importantly, consistently reaches smaller formally guaranteed worst-case network latencies than static TDM for realistic levels of utilization.