Pulser: Fast Congestion Response using Explicit Incast Notifications for Datacenter Networks

TL;DR

Pulser is a novel congestion control scheme for datacenter networks that uses Explicit Incast Notifications to quickly detect incast congestion, enabling faster response and improved performance over existing methods.

Contribution

The paper introduces EIN for fast incast detection and Pulser, a congestion control scheme that reacts promptly to incast, outperforming prior schemes in experiments and simulations.

Findings

Pulser reduces flow completion times significantly.

Pulser achieves higher throughput than DCTCP and ICTCP.

EIN enables accurate and rapid incast detection.

Abstract

Datacenter applications frequently cause incast congestion, which degrades both flow completion times of short flows and throughput of long flows. Without isolating incast, existing congestion control schemes (e.g., DCTCP) rely on existing ECN signal to react to general congestion, and they lose performance due to their slow, cautious, and inaccurate reaction to incast. We propose to isolate incast using Explicit Incast Notifications (EIN) that are generated by switches, similar to ECN. Our incast detection is fast and accurate. Further, we present our congestion control scheme, called Pulser, which drastically backs off during incast based on EIN, but restores sending rate once incast ends. Our real experiments and ns-3 simulations show that Pulser outperforms prior schemes, DCTCP and ICTCP, in both flow completion times and throughput.