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Xuan Liao

PROFILE

Xuan Liao

Over an 11-month period, this developer engineered quantized attention and performance optimizations across PyTorch and related repositories, focusing on CPU efficiency for large-scale deep learning models. They implemented INT8 and FP8 Scaled Dot Product Attention (SDPA) paths, AVX-512 accelerated C++ kernels, and autotuning for transformer workloads, while also addressing reliability through targeted bug fixes and expanded unit testing. Their work in pytorch/ao and pytorch/pytorch included kernel-level enhancements, quantization template support, and NUMA-aware benchmarking, leveraging C++, Python, and vectorization techniques. These contributions improved inference throughput, reduced latency, and strengthened testing coverage for quantized and distributed machine learning pipelines.

Overall Statistics

Feature vs Bugs

76%Features

Repository Contributions

29Total
Bugs
6
Commits
29
Features
19
Lines of code
17,861
Activity Months11

Work History

May 2026

2 Commits • 2 Features

May 1, 2026

May 2026 focused on CPU-friendly quantization and attention workloads across two core PyTorch repos, delivering tangible performance gains and strengthening testing coverage. Key contributions include FP8 template support and optimized CPU kernels for quantized operations, plus performance-focused enhancements to flash decoding in the attention pipeline, with NUMA-aware benchmarks validating significant speedups on large models.

April 2026

1 Commits

Apr 1, 2026

Month: 2026-04 — pytorch/ao: Focused on reliability and correctness of Quantized Scaled Dot Product Attention (QSDPA) on the CPU path. Key outcomes include a bug fix for strided input handling, ensuring output contiguity and correctness, along with test enhancements validating strided inputs. This work reduces risk of subtle errors in quantized attention across downstream models and improves performance through contiguous outputs. Commit reference: bbe615c45569f4a3e6d8a0349898a95f290be546. Overall impact: increased stability of QSDPA, expanded test coverage, and more deterministic behavior for non-contiguous inputs. Technologies/skills demonstrated: CPU-focused QSDPA internals, C++/Python testing, regression testing, and contribution workflow to PyTorch.

January 2026

2 Commits • 1 Features

Jan 1, 2026

Month: 2026-01 | PyTorch AO repo (pytorch/ao) delivered key quantization performance improvements focused on FP8 and INT8 SDPA. CPU-path optimizations reduce quantization overhead and improve inference throughput. No major bugs reported this month. This work strengthens the quantized inference path and demonstrates proficiency in quantization, performance tuning, and cross-type optimization.

December 2025

2 Commits • 1 Features

Dec 1, 2025

December 2025 performance highlights focused on delivering business value through performance improvements for large-scale models and improved runtime stability. The work spanned CPU kernel optimization in a core model path and stability/error-handling improvements in a widely used framework, reinforcing reliability for production workloads.

October 2025

1 Commits • 1 Features

Oct 1, 2025

October 2025: Delivered FP8 Quantization Support for Efficient Attention in pytorch/ao, enabling FP8 quantization and dequantization paths and SDPA pattern matching. The work introduces FP8-specific data types and transformer attention optimization paths, positioned to improve throughput and memory efficiency for large-scale attention workloads.

September 2025

5 Commits • 4 Features

Sep 1, 2025

September 2025 focused on expanding FP8/INT8 quantization on CPU and strengthening stability across PyTorch repos. Delivered CPU-side FP8 SDPA support with new kernels and tests, fixed FP8 SDPA compilation issues for PyTorch, and optimized INT8 SDPA kernels for memory and speed, enabling faster quantized inference. Expanded TorchAO and PyTorch quantization capabilities (transpose/pack optimization, aten.reshape.default support) with updated measurement metrics, improving performance visibility. Result: higher throughput for quantized models, broader hardware compatibility, and stronger CI/test coverage.

August 2025

1 Commits

Aug 1, 2025

August 2025 monthly summary for pytorch/ao: Focused on stabilizing Int8 SDPA fusion tests and improving test coverage. Delivered a targeted unit test fix addressing an assertion error and expanded coverage by adding a new operation to the test suite, enhancing reliability of the feature in CI and future releases. Resulted in more stable CI signals, reduced regression risk, and clearer validation for the Int8 SDPA fusion workflow.

July 2025

6 Commits • 4 Features

Jul 1, 2025

July 2025 performance and reliability update: Delivered CPU-focused optimizations and reliability improvements across PyTorch and AI reference models, boosting throughput for 8-bit quantized workloads and transformer attention, while hardening edge cases and test coverage. Key features include AVX-512 INT8 path, Grouped Query Attention (GQA) support in CPU Flash Attention, INT8 SDPA manual transpose/packing, and autotuning for ViT/BERT large models. Major bugs addressed include FakeTensorMode safety guards to prevent runtime errors with non-Fake inputs and fixes for bf16 memory access and None handling in attention backward paths. These contributions collectively improve performance, energy efficiency, and stability for CPU ML workloads, enabling more scalable inference and training on commodity hardware. Technologies demonstrated include AVX-512 vectorization, int8 quantization, sbgemm, GQA, Flash Attention, and autotuning workflows.

June 2025

4 Commits • 3 Features

Jun 1, 2025

June 2025 performance summary: Delivered cross-repo performance optimizations and distributed computing enhancements across intel/ai-reference-models, pytorch/ao, and pytorch/pytorch. Key outcomes include notable inference performance gains on CPU through INT8 SDPA quantization, AVX512-accelerated C++ kernels, and AOTI shims for distributed collectives, with accompanying tests and deployment-ready updates. These workstreams improved throughput, reduced latency, and expanded hardware support, contributing to faster model iteration and scalable distributed training/inference.

May 2025

2 Commits • 1 Features

May 1, 2025

Concise monthly summary for 2025-05 focused on the INT8 SDPA path for CPU in the pytorch/ao repo. Delivered a complete INT8 Scaled Dot Product Attention (SDPA) implementation and CPU template to accelerate quantized models, with new kernels, memory management optimizations, and integration with TorchAO quantization utilities. Added comprehensive tests to validate compatibility across input types and configurations, and re-landed key PRs to stabilize the feature set.

April 2025

3 Commits • 2 Features

Apr 1, 2025

April 2025 performance highlights across intel/ai-reference-models and pytorch/ao. Focused on quantization-driven performance and accuracy improvements: implemented INT8 quantization with refined evaluation logic, fixed a training/evaluation accuracy issue, and introduced a comprehensive INT8 SDPA CPU path with new kernels, framework integration, and tests, enabling faster, more efficient quantized inference across CPU workloads.

Activity

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Quality Metrics

Correctness92.4%
Maintainability80.6%
Architecture87.6%
Performance90.4%
AI Usage40.6%

Skills & Technologies

Programming Languages

C++PythonShellbash

Technical Skills

AVX-512AVX512Bash ScriptingC++C++ developmentC++ programmingCPU DevelopmentCPU optimizationCUDACUDA programmingDeep LearningDevOpsMachine LearningModel OptimizationNumerical computing

Repositories Contributed To

4 repos

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

pytorch/ao

Apr 2025 May 2026
10 Months active

Languages Used

C++Python

Technical Skills

CPU optimizationPyTorchdeep learningquantizationC++ developmentPython programming

pytorch/pytorch

Jun 2025 May 2026
5 Months active

Languages Used

C++Python

Technical Skills

C++ developmentPython testingdistributed computingunit testingAVX-512C++

intel/ai-reference-models

Apr 2025 Jul 2025
3 Months active

Languages Used

PythonShellbash

Technical Skills

Deep LearningMachine LearningModel OptimizationPyTorchBash ScriptingDevOps

kvcache-ai/sglang

Dec 2025 Dec 2025
1 Month active

Languages Used

C++Python

Technical Skills

CPU optimizationCUDA programmingDeep LearningMachine LearningUnit Testing