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Stanford University Networking Seminar

Kai Chen (Hong Kong University of Science and Technology, HKUST)
Information-Agnostic Flow Scheduling for Commodity Datacenters

1:45pm, Monday, May 16 2016
Gates 104

About the Talk

In our HKUST SING research group, we have been working on datacenter networks for years. In this talk, I will first briefly overview the lab datacenter platforms we built and research works we conducted in the last 3 years, centered around 2 SIGCOMM papers, 3 NSDI papers, and a few ongoing ones. Then, I will pick one of them called PIAS, Practical Information-Agnostic flow Scheduling for commodity datacenters, and discuss the details.

PIAS was motivated by the observation that many prior datacenter flow scheduling schemes minimize flow completion times (FCT) assuming prior knowledge of flows and custom switch functions. This makes them exciting in performance, but hard to use in practice. By PIAS, we present a scheme to minimize FCT with no prior knowledge and existing commodity switch functions. At its heart, PIAS leverages multiple priority queues available in existing commodity switches to implement a Multiple Level Feedback Queue (MLFQ), in which a PIAS flow is gradually demoted from higher-priority queues to lower-priority queues based on the amount of bytes it has sent. As a result, short flows are likely to be completed in the first few high-priority queues and thus be prioritized over long flows in general, which enables PIAS to emulate SJF without knowing flow sizes in advance. PIAS is readily implementable with commodity switches and backward compatible with legacy TCP/IP stacks. We have shown the superior performance of PIAS through both testbed experiments and ns2 simulations. To make our work easy to reproduce, we made all our implementation and evaluation scripts online at:

About the Speaker

Kai Chen is an Assistant Professor with Department of Computer Science and Engineering at Hong Kong University of Science and Technology (HKUST), where he leads the SING research group. He received his BS and MS from University of Science and Technology of China (USTC) in 2004 and 2007, and PhD from Northwestern University in 2012, all in Computer Science. His research interests include networked systems design and implementation, data center networks, data centric networking, cloud and big data systems. More information can be found at: