Deploying User-space TCP at Cloud Scale with LUNA


Lingjun Zhu, Yifan Shen, Erci Xu, Bo Shi, Ting Fu, Shu Ma, Shuguang Chen, Zhongyu Wang, Haonan Wu, Xingyu Liao, Zhendan Yang, Zhongqing Chen, Wei Lin, Yijun Hou, Rong Liu, Chao Shi, Jiaji Zhu, and Jiesheng Wu, Alibaba Group


The TCP remains the workhorse protocol for many modern large-scale data centers. However, the increasingly demanding performance expectations—led by advancement in both hardware (e.g., 100Gbps linkspeed network) and software (e.g., Intel DPDK support)—make the kernel-based TCP stack no longer a favorable option. Over the past decade, multiple parties have proposed various user-stack TCP stacks offering things-as-usual TCP support with significant performance improvement. Unfortunately, we find these proposals may not function well in the field, especially in large-scale deployments. In this paper, we present LUNA, a user-space TCP stack widely deployed at Alibaba Cloud. We demonstrate the design tradeoffs, emphasizing three unique features in thread, memory, and traffic models. Further, we discuss our lessons and experiences learned from the field deployment. The extensive microbenchmark evaluations and performance statistics collected from the production systems indicate that LUNA outperforms kernel and other user-space solutions with up to 3.5× in throughput and reduces up to 53% latency.

USENIX ATC '23 Open Access Sponsored by
King Abdullah University of Science and Technology (KAUST)

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This content is available to:

@inproceedings {288790,
author = {Lingjun Zhu and Yifan Shen and Erci Xu and Bo Shi and Ting Fu and Shu Ma and Shuguang Chen and Zhongyu Wang and Haonan Wu and Xingyu Liao and Zhendan Yang and Zhongqing Chen and Wei Lin and Yijun Hou and Rong Liu and Chao Shi and Jiaji Zhu and Jiesheng Wu},
title = {Deploying User-space {TCP} at Cloud Scale with {LUNA}},
booktitle = {2023 USENIX Annual Technical Conference (USENIX ATC 23)},
year = {2023},
isbn = {978-1-939133-35-9},
address = {Boston, MA},
pages = {673--687},
url = {},
publisher = {USENIX Association},
month = jul

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