Mapping the effects of mechanisms in Linux that affect the latency for thin-streams over TCP

Master

Thin streams over TCP are flows with high intertransmission-time between packets and small packet sizes. Such flows often experience increased retransmission latency because the recovery mechanisms in TCP were designed for greedy traffic. In the Linux kernel, there are a range of TCP mechanisms that can affect the latency for such flows. However, the interaction between them has not been explored. As an example, we have observed that turning on Tail loss probe (TLP) will drastically reduce the effect from several other thin-stream mechanisms (Like Early Retransmit and TCP_THIN_DUPACK).

Goal:

To evaluate the interaction between Linux kernel mechanisms affecting thin-stream latency and to understand the compound effect of such mechanisms. A possible outcome can be a set of recommendations for settings to enable for thin-stream traffic hosted on a Linux server.

Learning outcome:

- Knowledge about TCP, thin streams and interactive applications.

- Knowledge about TCP networking mechanisms in Linux.

- Knowledge of the Linux kernel network stack.

- Knowledge about statistical processing of large datasets.

Qualifications/background:

- Basic networking skills

- Linux skills

- Programming skills (C / C++, scripting)

Department:

Media Performance Group / Networks and Distributed systems

Contact person:

Andreas Petlund / Carsten Griwodz