# Chijun Sima

> Computer Science PhD student at The University of Texas at Austin, working on machine learning for systems and systems for machine learning. Co-first author of Ekko (OSDI 2022). LLVM developer with commit access.

Computer Science PhD student, The University of Texas at Austin, Austin, Texas, USA. Research interests: machine learning for systems; systems for machine learning. Contact: simachijun@gmail.com. Last updated 2026-10-02.

## Profile

- [Homepage](https://www.chijunsima.com/): Publications, experience, education, talks, awards, and links.
- [Google Scholar](https://scholar.google.com/citations?user=8-HD_IEAAAAJ&hl=en): Full publication list.
- [LinkedIn](https://www.linkedin.com/in/chijun-sima/): Professional profile.
- [Chenfeng Xu](https://www.chenfengx.com): Advisor (Assistant Professor, The University of Texas at Austin).
- [Aditya Akella](https://www.cs.utexas.edu/~akella/): Advisor (Professor & Regents Chair, The University of Texas at Austin).

## Flagship work

- [Ekko: A Large-Scale Deep Learning Recommender System with Low-Latency Model Update](https://www.usenix.org/conference/osdi22/presentation/sima): OSDI '22. Low-latency model update system for multi-terabyte deep learning recommendation models, achieving 2.4s update latency, 10,000x model-size scaling, and large production impact in WeChat.

## Data

- [llms-full.txt](https://www.chijunsima.com/llms-full.txt): Expanded context for deeper agent or retrieval workflows.
- [profile.json](https://www.chijunsima.com/profile.json): Machine-readable profile, experience, contact, and links.
- [publications.json](https://www.chijunsima.com/publications.json): Selected publications in a clean JSON structure.

## Optional

- [feed.json](https://www.chijunsima.com/feed.json): JSON Feed of publications and career milestones.
- [openapi.json](https://www.chijunsima.com/openapi.json): OpenAPI description for the public read-only profile endpoints.
- [agent skills](https://www.chijunsima.com/.well-known/agent-skills/index.json): Agent Skills discovery index for using the site profile endpoints.