Bufferbloat and Beyond - Removing Performance Barriers in Real-World Networks

by Toke Høiland-Jørgensen

The topic of this thesis is the performance of computer networks in general, and the internet in particular. While network performance has generally improved with time, over the last several years we have seen examples of performance barriers limiting network performance. In this work we explore such performance barriers and look for solutions.

Our exploration takes us through three areas where performance barriers are found: The bufferbloat phenomenon of excessive queueing latency, the performance anomaly in WiFi networks and related airtime resource sharing problems, and the problem of implementing high-speed programmable packet processing in an operating system. In each of these areas we present solutions that significantly advance the state of the art.

The work in this thesis spans all three aspects of the field of computing, namely mathematics, engineering and science. We perform mathematical analysis of algorithms, engineer solutions to the problems we explore, and perform scientific studies of the network itself. All our solutions are implemented as open source software, including both contributions to the upstream Linux kernel, as well as the Flent test tool, developed to support the measurements performed in the rest of the thesis.

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Reviews

[Nick Black · Rating 3 out of 5]

a few solid papers (CAKE and the original XDP papers), but definitely a "handful of papers stapled together" dissertation.

[Federico Lucifredi · Rating 5 out of 5]

The ultimative treatment of the subject of buffer-induced latency in computer networks.