Weitao Wang, Google LLC and Rice University; Masoud Moshref, Yuliang Li, and Gautam Kumar, Google LLC; T. S. Eugene Ng, Rice University; Neal Cardwell and Nandita Dukkipati, Google LLC
The difficulty in gaining visibility into the fine-timescale hop-level congestion state of networks has been a key challenge faced by congestion control (CC) protocols for decades. However, the emergence of commodity switches supporting in-network telemetry (INT) enables more advanced CC. In this paper, we present Poseidon, a novel CC protocol that exploits INT to address blind spots of CC algorithms and realize several fundamentally advantageous properties. First, Poseidon is efficient: it achieves low queuing delay, high throughput, and fast convergence. Furthermore, Poseidon decouples bandwidth fairness from the traditional AIMD control law, using a novel adaptive update scheme that converges quickly and smooths out oscillations. Second, Poseidon is robust: it realizes CC for the actual bottleneck hop, and achieves maxmin fairness across traffic patterns, including multi-hop and reverse-path congestion. Third, Poseidon is practical: it is amenable to incremental brownfield deployment in networks that mix INT and non-INT switches. We show, via testbed and simulation experiments, that Poseidon provides significant improvements over the state-of-the-art Swift CC algorithm across key metrics – RTT, throughput, fairness, and convergence – resulting in end-to-end application performance gains. Evaluated across several scenarios, Poseidon lowers fabric RTT by up to 50%, reduces time to converge up to 12×, and decreases throughput variation across flows by up to 70%. Collectively, these improvements reduce message transfer time by more than 61% on average and 14.5× at 99.9p.
Open Access Media
USENIX is committed to Open Access to the research presented at our events. Papers and proceedings are freely available to everyone once the event begins. Any video, audio, and/or slides that are posted after the event are also free and open to everyone. Support USENIX and our commitment to Open Access.