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Jonathan Clohessy

PROFILE

Jonathan Clohessy

Jonathan Clohessy contributed to high-performance machine learning runtimes, focusing on matrix multiplication and quantization optimizations in repositories such as google/XNNPACK and intel/onnxruntime. He engineered ARM SME-optimized microkernels and enhanced GEMM and convolution paths, using C and C++ to improve inference speed and memory efficiency. Jonathan refactored build systems with CMake, introduced runtime configurability, and strengthened test coverage to reduce production risk. His work included debugging low-level kernel issues, implementing logging for observability, and optimizing memory management. These efforts resulted in faster, more reliable inference and streamlined cross-architecture integration, demonstrating depth in embedded systems and performance-critical algorithm design.

Overall Statistics

Feature vs Bugs

64%Features

Repository Contributions

19Total
Bugs
5
Commits
19
Features
9
Lines of code
2,720
Activity Months5

Work History

February 2026

4 Commits • 1 Features

Feb 1, 2026

February 2026 monthly summary for CodeLinaro/onnxruntime focusing on KleidiAI kernel performance, reliability, and logging enhancements, plus a critical bug fix for dynamic QGEMM pack B size. Delivered performance optimizations, expanded test coverage, and improved kernel maintainability, enabling faster and more reliable model inference across workloads.

December 2025

5 Commits • 3 Features

Dec 1, 2025

2025-12 Performance Summary: Delivered high-impact performance and maintainability improvements across two key codebases (google/XNNPACK and intel/onnxruntime) with ARM SME2-optimized microkernels and GEMV-based SGEMM paths. The month centered on delivering concrete capabilities with clear business value: faster inference times on targeted workloads, easier cross-architecture integration, and stronger debugging/observability. Key outcomes include introducing an IGEMM PF32 microkernel for ARM SME2 in XNNPACK with a packing variant and initialization logging; refactoring KleidiAI microkernel integration to streamline conditional compilation for SME1/SME2; and adding a high-performance SGEMM path for single-row/column cases in ONNX Runtime using GEMV kernels with a microkernel interface to simplify SME1/SME2 adoption. These changes were supported by build integration, debug logging, and instrumentation improvements, enabling more predictable performance and easier future enhancements. Overall impact: tangible speedups in targeted GEMV/SGEMM workloads, reduced integration complexity across microkernels, and better developer productivity through instrumentation and cleaner conditional compilation. Technologies/skills demonstrated: ARM SME2 packing variants, initialization/logging instrumentation, conditional compilation refactors, GEMV-based SGEMM implementation, microkernel interface design, and performance benchmarking across two leading ML runtimes.

November 2025

3 Commits • 2 Features

Nov 1, 2025

Concise monthly summary for Nov 2025 highlighting performance improvements, configurability enhancements, and stability gains across ONNX Runtime and XNNPACK. Focused on delivering business value through faster dynamic quantization paths, greater runtime flexibility, and robust test coverage to reduce risk in production deployments.

October 2025

6 Commits • 3 Features

Oct 1, 2025

October 2025 performance summary for google/XNNPACK and intel/onnxruntime. Delivered key performance and compatibility improvements across ARM-based targets, with a focus on FP16 optimization, SME-accelerated GEMMs, and build/test stability. Emphasized business value through throughput gains, reduced memory overhead, and broader platform readiness.

August 2025

1 Commits

Aug 1, 2025

August 2025: ONNX Runtime – Quantization correctness and test-stability improvements. Delivered a targeted correctness fix for DynamicQuantizeMatMul and Attention3D by preventing invalid B scales and correctly handling GEMM edge cases in tests. The change reduces test flakiness and fortifies quantized inference reliability, aligning with production quality goals for quantized models.

Activity

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Quality Metrics

Correctness91.0%
Maintainability83.2%
Architecture86.8%
Performance89.4%
AI Usage30.6%

Skills & Technologies

Programming Languages

CC++CMakeYAML

Technical Skills

ARM NEONC programmingC++C++ developmentC++ programmingCMakeConditional compilationEmbedded SystemsKernel developmentLogging implementationMachine LearningMemory ManagementMicrokernel architecturePerformance OptimizationTesting frameworks

Repositories Contributed To

4 repos

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

google/XNNPACK

Oct 2025 Dec 2025
3 Months active

Languages Used

CC++YAMLCMake

Technical Skills

C++ developmentConditional compilationTesting frameworksalgorithm optimizationembedded systemslow-level programming

intel/onnxruntime

Oct 2025 Dec 2025
3 Months active

Languages Used

C++

Technical Skills

ARM NEONC++C++ developmentEmbedded SystemsMemory ManagementPerformance Optimization

CodeLinaro/onnxruntime

Feb 2026 Feb 2026
1 Month active

Languages Used

C++

Technical Skills

C++C++ developmentC++ programmingKernel developmentLogging implementationMachine Learning

microsoft/onnxruntime

Aug 2025 Aug 2025
1 Month active

Languages Used

C++

Technical Skills

C++ developmentalgorithm optimizationmachine learning