A Linux Kernel Implementation of the Homa Transport Protocol


John Ousterhout, Stanford University


Homa/Linux is a Linux kernel module that implements the Homa transport protocol. Measurements of Homa/Linux reconfirm Homa's superior performance compared to TCP and DCTCP. In a cluster benchmark with 40 nodes, Homa/Linux provided lower latency than both TCP and DCTCP for all message sizes; for short messages, Homa's 99th percentile tail latency was 7–83x lower than TCP and DCTCP. The benchmarks also show that Homa has eliminated network congestion as a significant performance limitation. Both tail latency and throughput are now limited by software overheads, particularly software congestion caused by imperfect load balancing of the protocol stack across cores. Another factor of 5–10x in performance can be achieved if software overheads can be eliminated in the future.

Open Access Media

USENIX is committed to Open Access to the research presented at our events. Papers and proceedings are freely available to everyone once the event begins. Any video, audio, and/or slides that are posted after the event are also free and open to everyone. Support USENIX and our commitment to Open Access.

@inproceedings {273859,
author = {John Ousterhout},
title = {A Linux Kernel Implementation of the Homa Transport Protocol},
booktitle = {2021 USENIX Annual Technical Conference (USENIX ATC 21)},
year = {2021},
isbn = {978-1-939133-23-6},
pages = {99--115},
url = {https://www.usenix.org/conference/atc21/presentation/ousterhout},
publisher = {USENIX Association},
month = jul,

Presentation Video