Never Been KIST: Tor's Congestion Management Blossoms with Kernel-Informed Socket Transport
Abstract
Tor s growing popularity and user diversity has resulted in network performance problems that are not well understood. A large body of work has attempted to solve these problems without a complete understanding of where congestion occurs in Tor. In this paper, we first study congestion in Tor at individual relays as well as along the entire end-to-end Tor path and find that congestion occurs almost exclusively in egress kernel socket buffers. We then analyze Tor s socket interactions and discover two major issues affecting congestion: Tor writes sockets sequentially, and Tor writes as much as possible to each socket. We thus design, implement, and test KIST: a new socket management algorithm that uses real-time kernel information to dynamically compute the amount to write to each socket while considering all writable circuits when scheduling new cells. We find that, in the medians, KIST reduces circuit congestion by over 30 percent, reduces network latency by 18 percent, and increases network throughput by nearly 10 percent.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2014
- Accession Number
- ADA620987
Entities
People
- Chris Wacek
- John Geddes
- Micah Sherr
- Paul Syverson
- Rob Jansen
Organizations
- United States Naval Research Laboratory