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Xiaofei Han

PROFILE

Xiaofei Han

Xiaofei Han contributed to ONNX Runtime repositories such as ROCm/onnxruntime and microsoft/onnxruntime, focusing on GPU programming, performance optimization, and shader development. Over eight months, Xiaofei unified and optimized core matrix operations, implemented fused kernels for rotary embeddings, and enabled large-model inference on WebGPU by segmenting buffers and aligning with CUDA parity. Using C++, Python, and WGSL, Xiaofei improved test reliability, fixed build and type mismatch issues, and enhanced profiling and CI stability. The work demonstrated depth in debugging, kernel fusion, and cross-platform GPU integration, resulting in more maintainable code and measurable throughput gains for large-scale machine learning workloads.

Overall Statistics

Feature vs Bugs

64%Features

Repository Contributions

16Total
Bugs
5
Commits
16
Features
9
Lines of code
6,127
Activity Months8

Work History

January 2026

2 Commits • 1 Features

Jan 1, 2026

January 2026 monthly summary for CodeLinaro/onnxruntime: Focused on stabilizing CUDA CI and improving runtime observability with per-run profiling. Implemented Abseil compatibility patch to address CUDA CI warnings/errors and introduced run-level profiling support, enabling per-run profiling data storage in JSON and ensuring data integrity across runs.

December 2025

1 Commits

Dec 1, 2025

December 2025 monthly summary focusing on key accomplishments and business impact. This period centered on stability and correctness improvements in the WebGPU execution path for ROCm/onnxruntime, with targeted fixes to ensure parity between debug and release modes.

November 2025

2 Commits • 1 Features

Nov 1, 2025

November 2025: Delivered performance-oriented WebGPU integrations in ROCm/onnxruntime by introducing fused QKV pathways with rotary embeddings and CopyKVCache, resulting in measurable throughput gains on NV5080. Implemented two fused kernels that accelerate token generation by about 3-4% on NV5080, with supporting Linux/Windows benchmarks and forward-looking notes for broader GPU coverage. No high-priority bug fixes were reported this month; emphasis was on feature delivery and performance validation. The work reduces latency and increases throughput for WebGPU ONNX Runtime scenarios, strengthening market competitiveness and user experience for browser-based and GPU-accelerated inference.

October 2025

4 Commits • 2 Features

Oct 1, 2025

October 2025: Implemented WebGPU-based large-buffer handling and rotary-embedding optimizations in ROCm/onnxruntime to enable large-model inference and improve generation throughput, while also tightening test reliability. Key outcomes include enabling phi-4 large-model processing via segmentation of inputs/outputs to respect maxStorageBufferBindingSize, adding getByOffset/setByOffset shader helpers, and aligning the WebGPU path with CUDA parity. Introduced Rotary Embedding (ROE) support in Flash Attention for WebGPU through a fused QKRotaryEmbeddingProgram, with GeneratePositionIDs fused into the ROE path to reduce kernel launches and CPU overhead. Together these changes delivered measurable speedups in token generation on high-end GPUs (over 5% on NVIDIA 5080 and ~4% on Apple M3 Max) and improved end-to-end throughput for large models. A companion fix corrected numpy test argument ordering to ensure accurate expected-vs-actual comparisons. Overall impact: expanded model capacity and performance on WebGPU, closer feature parity with CUDA, and a more reliable test suite. Tech stack demonstrated: WebGPU, shader helpers and multi-binding management, fused kernels, Rotary Embedding (ROE), GeneratePositionIDs, and performance-focused refactorings.

September 2025

2 Commits • 1 Features

Sep 1, 2025

September 2025: Delivered two WebGPU changes in microsoft/onnxruntime. 1) WGSL Shader Comments Restoration (Flash Decoding) — restored missing comments to improve readability and maintainability of flash decoding shaders. Commit: 5746ba9d3b7b5eaf3a5c64fd24974f3649d71b34. 2) MatMul Activation Member Safety Fix — changed activation member from a reference to a direct object to prevent potential dangling references and undefined behavior. Commit: ff66c70b914ff7e540d121e80be892e52377a143.

August 2025

2 Commits • 2 Features

Aug 1, 2025

Monthly performance summary for 2025-08 focusing on microsoft/onnxruntime. This period delivered targeted improvements in GPU testing and shader maintainability. GEMM testing enhancements for the WebGPU path broadened test coverage across alpha/beta variations and varied matrix sizes/types. A shader refactor moved flash decoding shaders into templates, improving readability and long-term maintainability. No major bugs were reported in this repository this month; the work strengthens stability and supports continued GPU optimization.

June 2025

2 Commits • 2 Features

Jun 1, 2025

June 2025 monthly summary focusing on key accomplishments, major bugs fixed, and overall impact. Highlights across mozilla/onnxruntime and microsoft/onnxruntime include feature development and performance optimizations that improve cross-vendor GPU performance and maintainability. Key deliverables: 1) Unified GEMM and MatMul core implementations consolidated in gemm_utils.cc, reducing code duplication and improving maintainability for scalar and vectorized paths; 2) ONNX Runtime Convolution performance optimization by removing the sequentially_access_by_threads flag to enhance GPU convolution efficiency across vendors, particularly for non-vec4 packed cases. Impact includes streamlined code, better performance, and measurable efficiency gains across typical workloads. Technologies/skills demonstrated include GPU-aware kernel unification, performance testing, vectorization, and cross-repo collaboration.

May 2025

1 Commits

May 1, 2025

Month: 2025-05. Focus: deliver a robust macOS XCode build for Node.js bindings in mozilla/onnxruntime; key bug fix and its business impact. Highlights include diagnosing and fixing a build failure caused by an incorrect dynamic library directory path, enabling successful builds under macOS XCode configuration. This work improves developer productivity, CI reliability, and broader adoption of the Node.js bindings on macOS.

Activity

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Quality Metrics

Correctness99.4%
Maintainability88.8%
Architecture93.2%
Performance88.2%
AI Usage25.0%

Skills & Technologies

Programming Languages

C++CMakePythonWGSL

Technical Skills

API designBuffer ManagementC++C++ developmentCMakeCUDACompute ShadersConvolutional neural networksDebuggingGPU ProgrammingGPU programmingKernel FusionMachine Learning KernelsMachine learningMatrix Multiplication

Repositories Contributed To

4 repos

Overview of all repositories you've contributed to across your timeline

ROCm/onnxruntime

Oct 2025 Dec 2025
3 Months active

Languages Used

C++PythonWGSL

Technical Skills

Buffer ManagementCompute ShadersDebuggingGPU programmingKernel FusionMachine Learning Kernels

microsoft/onnxruntime

Jun 2025 Sep 2025
3 Months active

Languages Used

C++WGSL

Technical Skills

Convolutional neural networksGPU programmingPerformance optimizationC++GPU ProgrammingMatrix operations

mozilla/onnxruntime

May 2025 Jun 2025
2 Months active

Languages Used

CMakeC++

Technical Skills

CMakeNode.jsmacOS DevelopmentGPU ProgrammingMatrix MultiplicationPerformance Optimization

CodeLinaro/onnxruntime

Jan 2026 Jan 2026
1 Month active

Languages Used

C++CMake

Technical Skills

API designC++ developmentCMakeCUDAperformance profiling

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