Improved formal worst-case timing analysis of weighted round robin scheduling for Ethernet

Abstract

Ethernet networks become increasingly popular in many distributed embedded applications. As an alternative to strict priority (SP) scheduling, weighted round robin (WRR) is supported by most commercially available Ethernet switches. In WRR scheduling the link capacity is distributed fairly among traffic streams according to preset weights on a per round basis. As WRR does not provide latency guarantees, formal timing verification is necessary in order to deploy WRR in real-time applications. In this paper, we present a formal method to analyze WRR scheduling in Ethernet networks. Compared to existing methods which overestimate by assuming unnecessarily high interference, our method will take actual load bounds into account, thus achieving tighter analysis results. Finally, we perform an evaluation of our approach against existing methods and also against SP scheduling.