Lequn Chen

Publications

AdaRes: Adaptive Resource Management for Virtual Machines

Ignacio Cano, Lequn Chen, Pedro Fonseca, Tianqi Chen, Chern Cheah, Karan Gupta, Ramesh Chandra, Arvind Krishnamurthy

arXiv, abs/1812.01837, 2018

Enabling Strong Database Integrity using Trusted Execution Environments

Kai Mast, Lequn Chen, and Emin Gün Sirer

arXiv, abs/1801.01618, 2018

Scaling Databases using Trusted Hardware Proxies

Kai Mast, Lequn Chen, and Emin Gün Sirer

Workshop on System Software for Trusted Execution, Shanghai, China, October 2017

Research Experiences

Systems Lab

Cornell University

Visiting Research Intern, advised by Emin Gün Sirer and Kai Mast Jul 2017 – Dec 2017

Worked on a database that provides blockchain-like guarantees of data integrity using Trusted Execution Environments.

Implemented large parts of the prototype on Intel SGX.
Boosted the performance inside the SGX enclave.
Increased the throughput of multi-client read workload 30x and reduced the latency by 40%.
Implemented transaction support with optimistic concurrency control.
Optimized query optimizer and executor, reducing cost of join operation to almost constant in typical workloads.
Found and solved dozens of deadlocks and data races in the initial version of the code.
Designed benchmarks and conducted experiments on a distributed testbed.

APEX Data & Knowledge Management Lab

Shanghai Jiao Tong University

Undergraduate Researcher, advised by Weinan Zhang Mar 2017 – Jun 2017

Worked on Computational Advertisement. Built a machine learning pipeline for an advertisement exchange startup.

Designed and trained a Click-Through Rate (CTR) estimation model.
Integrate the model with the startup's Real-Time Bidding (RTB) software stack.

Tianrang Network Technology Co.,Ltd

Shanghai

Research Intern, advised by Gui-Rong Xue Jun 2016 – Mar 2017

Worked on a program Yi playing board game Go similar to Google DeepMind's AlphaGo. Yi runs Monte-Carlo tree search algorithm, deep neural network, and reinforcement learning algorithms.

Designed and Implemented a distributed system running both CPU and GPU workers on multiple machines.
Reduced the network latency and increased single-machine performance.
Refactored the code base. Trained and tuned neural networks. It could beat entry-level professional human players.

Teaching Experiences

Compilers

Student Instructor Spring 2017

Led the teaching assistant team.
Redesigned assignments. Changed the target platform from SPIM MIPS Simulator to Linux x86-64, giving students more possibilities to do compilation optimization.
Built a Continuous Integration (CI) system. Once students pushed changes to their git repository, the CI would fetch the source code, compile it, test its performance on all test cases, and update the leaderboard.

Principle and Practice of Computer Algorithms

Student Instructor Summer 2016

Built an online judge system for algorithm exams.
Led a group of students to implement simplified MapReduce and Google File System. Deployed and benchmarked them on all machines of the computer room.

C++ Programming

Teaching Assistant Fall 2015

Gave a lecture on how to begin C++ projects. Review and make comments to students' projects.
Built an online judge system for the game bot project.
Carefully designed two sets of homework to help students master the basic idea of OOP in C++.

Highlighted Projects

Compiles C-and-Java-like language to MIPS assembly. I paid close attention to code generation and optimization. Features included graph coloring register allocation,transformation in Static Single Assignment form, and different kinds of optimizations.

Isolated Deep Learning Development Environment with Shared GPUs

Jun 2017

Deep learning needs graphics cards to speed up computation. Labs sometimes cannot afford to buy graphics cards for each member. Researchers are not always good at server administration. This is a solution to isolate users while giving them the root privilege and access to GPUs without sacrificing performance.

Daily Routine Surveillance Using QQ Network Status

Jul 2014

QQ, an instant messaging software with 900 million active users, added a new feature showing users' network status (e.g. Wi-Fi/2G/3G/4G) to friends, which gave rise to privacy concerns. I invented a method so that by monitoring this status and social engineering, users' daily routine could possibly be deduced.

Simplified Git

Jun 2015

A command line source code version control system, providing the ability to archive, restore and compare source code among different versions. I implemented an efficient diff algorithm, making the speed of comparing files very fast even when the file contains tens of thousands lines of code.

Lequn Chen (陈乐群)

Research Interests