Jiaxuan Chen

jiaxuan.chen@mila.quebec

PhD - McGill University

Supervisor

Oana Balmau

Co-supervisor

Xue (Steve) Liu

Research Topics

Computer Systems

Energy Systems

Large Language Models (LLM)

Publications

DeltaServe: Host-Agnostic Co-Serving of Inference and Fine-Tuning for LLMs

Jiaxuan Chen

Jianshu She

Ye Yuan

Rajat Ghosh

Karan Gupta

Qirong Ho

Xue Liu

Oana Balmau

LLM serving systems are provisioned for peak load to meet strict latency targets, leaving substantial GPU compute idle whenever traffic fall… (see more)s below peak. We present DeltaServe, a host-agnostic co-serving design that converts this idle inference capacity into LoRA fine-tuning throughput while preserving inference service-level objectives (SLOs). DeltaServe integrates with existing inference engines through a compact hook interface that requires only multi-LoRA batching support. It exploits the shared execution structure of inference prefill and LoRA fine-tuning forward passes, and uses an SLO-aware scheduler to admit and execute fine-tuning only when sufficient inference headroom is available. The scheduler is driven by a CUDA-graph-aware latency model calibrated offline and refined online. We integrate DeltaServe with vLLM, SGLang, and S-LoRA. On a production trace from Company X, DeltaServe on vLLM delivers 2.9x higher fine-tuning throughput than LLMStation at 100% inference SLO compliance, versus 85% for LLMStation. It also achieves 39% higher fine-tuning throughput than a baseline running vLLM+torchtune, using no additional hardware and maintaining full SLO compliance.

2026-07-29

arXiv (preprint)

doi.org

arxiv.org

The Cost of Expertise: Understanding MoE Decode Performance

Sami Abuzakuk

Oana Balmau

Jiaxuan Chen

Anne-Marie Kermarrec

Rafael Pires

Ramya Prabhu

Martijn de Vos