About me

I am currently a 4th-year Ph.D. candidate at the UCLA Computer Science Department. I have the privilege of working with Prof. Songwu Lu and the members of the WiNG. My research broadly covers machine learning and systems, with a current focus on LLM alignment [ICML 2025], reasoning, and ML for systems [MLSys 2024][NeurIPS 2023 Workshop]. I have a background in systems and algorithms including VR streaming [ATC ’25], 5G systems [SIGCOMM ’22][NSDI ’21][TMC], and data mining algorithms [KDD ’20][SIGCOMM ’22 Workshop][SANER 2021][TNSE]. Prior to UCLA, I received my B.S. in Computer Science from Peking University, where I also conducted research on sketch-based algorithms under the supervision of Prof. Tong Yang.

What’s New

[May 2025] Our work RLTHF is accepted to ICML 2025. See you in Vancouver!

[Apr. 2025] Our work MP2 is accepted to ATC ’25. See you in Boston!

[Feb. 2025] Check out our new work RLTHF available at Preprint!

[Feb. 2024] Our work CloudEval-YAML is accepted to MLSys 2024. See you in Santa Clara!

[Jan. 2024] I will be joining Microsoft Research as a Research Intern in Summer 2024. See you in Redmond!

[Nov. 2023] Our preliminary work on CloudEval-YAML is accepted to NeurIPS 2023 Workshop on ML for Systems. Check out the code here. See you in New Orleans!

Publications

Conference Papers

RLTHF: Targeted Human Feedback for LLM Alignment
Yifei Xu, Tusher Chakraborty, Emre Kıcıman, Bibek Aryal, Eduardo Rodrigues, Srinagesh Sharma, Roberto Estevao, Maria Angels de Luis Balaguer, Jessica Wolk, Rafael Padilha, Leonardo Nunes, Shobana Balakrishnan, Songwu Lu, Ranveer Chandra
ICML 2025 (To Appear) [arXiv]

Roaming Free in the VR World with MP2
Yifei Xu, Xumiao Zhang, Yuning Chen, Pan Hu, Xuan Zeng, Zhilong Zheng, Xianshang Lin, Yanmei Liu, Songwu Lu, Z. Morley Mao, Wan Du, Dennis Cai, Ennan Zhai, Yunfei Ma
ATC ’25 (To Appear)

CloudEval-YAML: A Practical Benchmark for Cloud Configuration Generation
Yifei Xu*, Yuning Chen*, Xumiao Zhang*, Xianshang Lin, Pan Hu, Yunfei Ma, Songwu Lu, Wan Du, Z. Morley Mao, Ennan Zhai, Dennis Cai
MLSys 2024 [pdf] [code]

SEED: a SIM-based solution to 5G failures
Jinghao Zhao, Zhaowei Tan, Yifei Xu, Zhehui Zhang, Songwu Lu
SIGCOMM 2022 [pdf]

Device-Based LTE Latency Reduction at the Application Layer
Zhaowei Tan, Jinghao Zhao, Yuanjie Li, Yifei Xu, Songwu Lu
NSDI ’21 [pdf]

A Multi-Metric Ranking Approach for Library Migration Recommendations
Hao He, Yulin Xu, Yixiao Ma, Yifei Xu, Guangtai Liang, Minghui Zhou
IEEE SANER 2021 [pdf]

WavingSketch: An Unbiased and Generic Sketch for Finding Top-k Items in Data Streams
Jizhou Li*, Zikun Li*, Yifei Xu*, Shiqi Jiang, Tong Yang, Bin Cui, Yafei Dai and Gong Zhang
SIGKDD 2020 [pdf]

Journals

Unbiased Real-time Traffic Sketching
Yuhan Wu*, Shiqi Jiang*, Yifei Xu*, Siyuan Dong, Kaicheng Yang, Peiqing Chen, Tong Yang
IEEE TNSE [pdf]

LDRP: Device-Centric Latency Diagnostic and Reduction for Cellular Networks Without Root
Zhaowei Tan, Jinghao Zhao, Yuanjie Li, Yifei Xu, Yunqi Guo, Songwu Lu
IEEE TMC [pdf]

Workshops, Posters, and Demos

CloudEval-YAML: A Realistic and Scalable Benchmark for Cloud Configuration Generation
Yifei Xu*, Yuning Chen*, Xumiao Zhang*, Xianshang Lin, Pan Hu, Yunfei Ma, Songwu Lu, Wan Du, Z. Morley Mao, Ennan Zhai, Dennis Cai
NeurIPS 2023 Workshop on ML for Systems [pdf]

PISketch: finding persistent and infrequent flows
Zhuochen Fan, Zhoujing Hu, Yuhan Wu, Jiarui Guo, Wenrui Liu, Tong Yang, Hengrui Wang, Yifei Xu, Steve Uhlig, Yaofeng Tu
SIGCOMM 2022 Workshop on FFSPIN [pdf]

* co-first author

Teaching

TA in UCLA CS Dept since 2022, courses include:
CS 180 - Introduction to Algorithms and Complexity
CS 118 - Computer Network Fundamentals
CS 31 - Introduction to Computer Science I
CS 35L - Software Construction