TIMELY: RTT-based congestion control for the datacenter

Radhika Mittal, Vinh The Lam, Nandita Dukkipati, Emily Blem, Hassan Wassel, Monia Ghobadi, Amin Vahdat, Yaogong Wang, David Wetherall, David Zats

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Datacenter transports aim to deliver low latency messaging together with high throughput. We show that simple packet delay, measured as round-trip times at hosts, is an effective congestion signal without the need for switch feedback. First, we show that advances in NIC hardware have made RTT measurement possible with microsecond accuracy, and that these RTTs are sufficient to estimate switch queueing. Then we describe how TIMELY can adjust transmission rates using RTT gradients to keep packet latency low while delivering high bandwidth. We implement our design in host software running over NICs with OS-bypass capabilities. We show using experiments with up to hundreds of machines on a Clos network topology that it provides excellent performance: Turning on TIMELY for OS-bypass messaging over a fabric with PFC lowers 99 percentile tail latency by 9X while maintaining near line-rate throughput. Our system also outperforms DCTCP running in an optimized kernel, reducing tail latency by 13X. To the best of our knowledge, TIMELY is the first delay-based congestion control protocol for use in the datacenter, and it achieves its results despite having an order of magnitude fewer RTT signals (due to NIC offload) than earlier delay-based schemes such as Vegas.

Original languageEnglish (US)
Title of host publicationSIGCOMM 2015 - Proceedings of the 2015 ACM Conference on Special Interest Group on Data Communication
PublisherAssociation for Computing Machinery, Inc
Pages537-550
Number of pages14
ISBN (Electronic)9781450335423
DOIs
StatePublished - Aug 17 2015
Externally publishedYes
EventACM Conference on Special Interest Group on Data Communication, SIGCOMM 2015 - London, United Kingdom
Duration: Aug 17 2015Aug 21 2015

Publication series

NameSIGCOMM 2015 - Proceedings of the 2015 ACM Conference on Special Interest Group on Data Communication

Other

OtherACM Conference on Special Interest Group on Data Communication, SIGCOMM 2015
Country/TerritoryUnited Kingdom
CityLondon
Period8/17/158/21/15

Keywords

  • Datacenter transport
  • Delay-based congestion control
  • Osbypass
  • Rdma

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Signal Processing
  • Electrical and Electronic Engineering
  • Communication

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