Deadline-Aware Datacenter TCP (D2TCP)
Venue
Proceedings of the ACM SIGCOMM (2012)
Publication Year
2012
Authors
Balajee Vamanan, Jahangir Hasan, T. N. Vijaykumar
BibTeX
Abstract
An important class of datacenter applications, called Online Data-Intensive (OLDI)
applications, includes Web search, online retail, and advertisement. To achieve
good user experience, OLDI applications operate under soft-real-time constraints
(e.g., 300 ms latency) which imply deadlines for network communication within the
applications. Further, OLDI applications typically employ tree-based algorithms
which, in the common case, result in bursts of children-to-parent traffic with
tight deadlines. Recent work on datacenter network protocols is either
deadline-agnostic (DCTCP) or is deadline-aware (D3) but suffers under bursts due to
race conditions. Further, D3 has the practical drawbacks of requiring changes to
the switch hardware and not being able to coexist with legacy TCP. We propose
Deadline-Aware Datacenter TCP (D2TCP), a novel transport protocol, which handles
bursts, is deadline-aware, and is readily deployable. In designing D2TCP, we make
two contributions: (1) D2TCP uses a distributed and reactive approach for bandwidth
allocation which fundamentally enables D2TCP’s properties. (2) D2TCP employs a
novel congestion avoidance algorithm, which uses ECN feedback and deadlines to
modulate the congestion window via a gamma-correction function. Using a small-scale
implementation and at-scale simulations, we show that D2TCP reduces the fraction of
missed deadlines compared to DCTCP and D3 by 75% and 50%, respectively.
