
Nicolas Decarli engineered high-performance data-path and kernel optimizations across repositories such as facebook/folly, pytorch/FBGEMM, and facebook/fbthrift. He focused on accelerating matrix operations, quantization, and serialization by leveraging ARM NEON and SVE intrinsics, C++ template metaprogramming, and low-level assembly. In FBGEMM, he delivered vectorized and architecture-specific routines for matrix multiplication and quantized inference, while in folly, he improved synchronization primitives and memory operations for ARM. His work in fbthrift enhanced protocol serialization throughput. Decarli’s contributions demonstrated deep understanding of hardware capabilities, careful benchmarking, and robust cross-architecture support, resulting in measurable throughput and latency improvements in production workloads.
March 2026 was a performance-focused sprint delivering architecture-aware optimizations in Folly’s core data-paths with measurable throughput and latency gains. No explicit user-reported bugs were documented this month; the emphasis was on delivering high-impact improvements with solid validation and peer reviews.
March 2026 was a performance-focused sprint delivering architecture-aware optimizations in Folly’s core data-paths with measurable throughput and latency gains. No explicit user-reported bugs were documented this month; the emphasis was on delivering high-impact improvements with solid validation and peer reviews.
February 2026 monthly summary focusing on architecture-specific performance improvements in folly on AArch64 and ARM, delivering tangible business value through lower latency and more efficient memory operations. Work spanned: F14Table performance optimizations on AArch64 with ~10% faster find; addition of ARM SVE memset with noticeably faster small-buffer memset; SparseMaskIter improvements for occupiedIter on AArch64 using CLZ instead of CTZ, plus overall gains in CopyCtor/Destructor/Clear; integration of clang builtin usage for bitReverse; removal of ZVA check to streamline memset. These changes reduce function call/loop latency in hot paths, improve throughput on ARM servers, and align with newer ARM ISA features, improving user-perceived performance and energy efficiency.
February 2026 monthly summary focusing on architecture-specific performance improvements in folly on AArch64 and ARM, delivering tangible business value through lower latency and more efficient memory operations. Work spanned: F14Table performance optimizations on AArch64 with ~10% faster find; addition of ARM SVE memset with noticeably faster small-buffer memset; SparseMaskIter improvements for occupiedIter on AArch64 using CLZ instead of CTZ, plus overall gains in CopyCtor/Destructor/Clear; integration of clang builtin usage for bitReverse; removal of ZVA check to streamline memset. These changes reduce function call/loop latency in hot paths, improve throughput on ARM servers, and align with newer ARM ISA features, improving user-perceived performance and energy efficiency.
January 2026 monthly summary for pytorch/FBGEMM: Delivered a targeted performance optimization for the matrix transpose path by refining the assembly routine’s register allocation and removing unnecessary register duplication. This change improves execution efficiency and throughput for transpose-heavy workloads, contributing to faster matrix operations in production workloads.
January 2026 monthly summary for pytorch/FBGEMM: Delivered a targeted performance optimization for the matrix transpose path by refining the assembly routine’s register allocation and removing unnecessary register duplication. This change improves execution efficiency and throughput for transpose-heavy workloads, contributing to faster matrix operations in production workloads.
December 2025 monthly summary for pytorch/FBGEMM focusing on performance and architecture improvements across ARM64 and x86 cores. Delivered consolidated kernel-level optimizations, architecture-specific variants, and new aarch64 paths to support 4-bit quantization and embedding workloads. Implemented inlined memory utilities to reduce overhead and improve cache locality. Result: higher CPU throughput, lower memory traffic, and broader ARM64 coverage for quantized models and embedding-heavy workloads.
December 2025 monthly summary for pytorch/FBGEMM focusing on performance and architecture improvements across ARM64 and x86 cores. Delivered consolidated kernel-level optimizations, architecture-specific variants, and new aarch64 paths to support 4-bit quantization and embedding workloads. Implemented inlined memory utilities to reduce overhead and improve cache locality. Result: higher CPU throughput, lower memory traffic, and broader ARM64 coverage for quantized models and embedding-heavy workloads.
November 2025 was a performance-focused month spanning PyTorch core and FBGEMM, delivering cross-repo features that boost CPU efficiency, vectorized data-paths, and quantization throughput. Key results include bf16 conversion performance improvements on aarch64/NEON with zero-extension of bf16 into a 32-bit float, extended OSS benchmarks covering all tensor-type combinations, and validation through targeted correctness tests and benchmarks. AdRanker received a CPU‑path optimization for AddMomentsVec and UpdateMomentsVec by reordering operations to reduce instruction throughput, improving service-lab performance. In FBGEMM, NEON-accelerated fused rowwise quantization for SBFloat/SBHalf and a NEON implementation for H- and N-bit fused rowwise paths delivered order-of-magnitude throughput improvements in representative workloads. A matmul partitioning optimization (8x1) in kleidi-ai further increased throughput across sizes. All work was validated with correctness tests and performance benchmarks, contributing to faster model quantization, lower latency in inference, and better CI coverage for performance characteristics. Business value highlights: - Faster data-type conversions and extended benchmarking enable more reliable performance budgets for mixed-precision paths. - Improved AdRanker CPU-path efficiency reduces latency in recommendations workloads. - Substantial gains in quantization and matmul primitives translate to higher inference throughput and lower per-inference cost. - Cross-repo collaboration demonstrates scalable performance work with measurable benchmarks.
November 2025 was a performance-focused month spanning PyTorch core and FBGEMM, delivering cross-repo features that boost CPU efficiency, vectorized data-paths, and quantization throughput. Key results include bf16 conversion performance improvements on aarch64/NEON with zero-extension of bf16 into a 32-bit float, extended OSS benchmarks covering all tensor-type combinations, and validation through targeted correctness tests and benchmarks. AdRanker received a CPU‑path optimization for AddMomentsVec and UpdateMomentsVec by reordering operations to reduce instruction throughput, improving service-lab performance. In FBGEMM, NEON-accelerated fused rowwise quantization for SBFloat/SBHalf and a NEON implementation for H- and N-bit fused rowwise paths delivered order-of-magnitude throughput improvements in representative workloads. A matmul partitioning optimization (8x1) in kleidi-ai further increased throughput across sizes. All work was validated with correctness tests and performance benchmarks, contributing to faster model quantization, lower latency in inference, and better CI coverage for performance characteristics. Business value highlights: - Faster data-type conversions and extended benchmarking enable more reliable performance budgets for mixed-precision paths. - Improved AdRanker CPU-path efficiency reduces latency in recommendations workloads. - Substantial gains in quantization and matmul primitives translate to higher inference throughput and lower per-inference cost. - Cross-repo collaboration demonstrates scalable performance work with measurable benchmarks.
October 2025 performance summary for ROCm/pytorch and pytorch/FBGEMM. This period emphasizes ARM-focused performance optimizations and vectorization, expanding ARM deployment options while maintaining correctness and broadening platform support. Key work includes consolidated NEON/SVE vectorization across numeric operations, enhanced type conversions, and quantized kernel improvements that collectively boost throughput and reduce latency on aarch64-based devices.
October 2025 performance summary for ROCm/pytorch and pytorch/FBGEMM. This period emphasizes ARM-focused performance optimizations and vectorization, expanding ARM deployment options while maintaining correctness and broadening platform support. Key work includes consolidated NEON/SVE vectorization across numeric operations, enhanced type conversions, and quantized kernel improvements that collectively boost throughput and reduce latency on aarch64-based devices.
September 2025 performance-focused month across PyTorch backends and ROCm. Delivered ARM-SVE acceleration and expanded SVE coverage for embedding and math workloads. Key outcomes include SVE-accelerated EmbeddingSpMDM8Bit on ARM in pytorch/FBGEMM with 10-25% throughput gains; Box-Cox performance optimization with SVE128 SIMD in ROCm/pytorch achieving 65% throughput improvement, plus compile guards and a 2% throughput increase from improved exp bound checking while preserving precision; SVE128 support and translation layers for PyTorch on ARM added in ROCm/pytorch with extensive testing. Build configuration updates accompany each feature to ensure robust SVE builds. Overall impact: higher performance on ARM-SVE paths, improved maintainability, and broader SVE coverage across embedding and numerical workloads.
September 2025 performance-focused month across PyTorch backends and ROCm. Delivered ARM-SVE acceleration and expanded SVE coverage for embedding and math workloads. Key outcomes include SVE-accelerated EmbeddingSpMDM8Bit on ARM in pytorch/FBGEMM with 10-25% throughput gains; Box-Cox performance optimization with SVE128 SIMD in ROCm/pytorch achieving 65% throughput improvement, plus compile guards and a 2% throughput increase from improved exp bound checking while preserving precision; SVE128 support and translation layers for PyTorch on ARM added in ROCm/pytorch with extensive testing. Build configuration updates accompany each feature to ensure robust SVE builds. Overall impact: higher performance on ARM-SVE paths, improved maintainability, and broader SVE coverage across embedding and numerical workloads.
Monthly performance summary for 2025-08: Delivered NEON-Accelerated RWSpinLock in facebook/folly, introducing NEON intrinsics to reduce lock/unlock overhead and improve unlock performance in high-concurrency scenarios on ARM. This optimization strengthens Folly's core synchronization primitives and enables better throughput for multi-threaded workloads. Major bugs fixed: none reported for this repository this month. Focus was on feature development and performance improvements. Technologies demonstrated: low-level concurrency design, ARM NEON intrinsics, C++ performance optimization, and code instrumentation for maintainability and review. Business value: lower latency in hot paths and improved scalability for services relying on Folly's synchronization primitives.
Monthly performance summary for 2025-08: Delivered NEON-Accelerated RWSpinLock in facebook/folly, introducing NEON intrinsics to reduce lock/unlock overhead and improve unlock performance in high-concurrency scenarios on ARM. This optimization strengthens Folly's core synchronization primitives and enables better throughput for multi-threaded workloads. Major bugs fixed: none reported for this repository this month. Focus was on feature development and performance improvements. Technologies demonstrated: low-level concurrency design, ARM NEON intrinsics, C++ performance optimization, and code instrumentation for maintainability and review. Business value: lower latency in hot paths and improved scalability for services relying on Folly's synchronization primitives.
July 2025 monthly summary highlighting key features, fixes, and impact across registered repositories. Focused on business value, stability, and performance improvements enabled by targeted code-path optimizations and CI reliability enhancements.
July 2025 monthly summary highlighting key features, fixes, and impact across registered repositories. Focused on business value, stability, and performance improvements enabled by targeted code-path optimizations and CI reliability enhancements.
June 2025 monthly summary: Focused on performance-driven feature work in two repos (pytorch/FBGEMM and facebook/fbthrift). Delivered hardware-accelerated and vectorized FP16 data paths and significant vectorization optimizations that improve throughput and efficiency on both general CPUs and aarch64. Key delivered items: FP16 conversion optimization with hardware acceleration and vectorization; FP16 matmul optimization via memory-load hoisting and Neon tweaks; Vectorized CompactProtocol write path on aarch64; Partial vectorized list read improvements for CompactProtocol. Impact: improved throughput for FP16 workloads and large-scale data processing, better utilization of modern CPU features, and expanded test coverage to ensure reliability under larger datasets. Technologies demonstrated: low-level optimization, SIMD/vectorization, Neon assembly, aarch64 specialization, performance testing.
June 2025 monthly summary: Focused on performance-driven feature work in two repos (pytorch/FBGEMM and facebook/fbthrift). Delivered hardware-accelerated and vectorized FP16 data paths and significant vectorization optimizations that improve throughput and efficiency on both general CPUs and aarch64. Key delivered items: FP16 conversion optimization with hardware acceleration and vectorization; FP16 matmul optimization via memory-load hoisting and Neon tweaks; Vectorized CompactProtocol write path on aarch64; Partial vectorized list read improvements for CompactProtocol. Impact: improved throughput for FP16 workloads and large-scale data processing, better utilization of modern CPU features, and expanded test coverage to ensure reliability under larger datasets. Technologies demonstrated: low-level optimization, SIMD/vectorization, Neon assembly, aarch64 specialization, performance testing.
May 2025 performance sprint for facebook/fbthrift focused on enhancing JSON serialization performance. Delivered JSONProtocol WriteJSONString Performance Optimization, with significant throughput improvements, especially on aarch64. No major bugs fixed in this scope this month. Emphasized cross-architecture profiling, efficient buffer handling, and clean code changes.
May 2025 performance sprint for facebook/fbthrift focused on enhancing JSON serialization performance. Delivered JSONProtocol WriteJSONString Performance Optimization, with significant throughput improvements, especially on aarch64. No major bugs fixed in this scope this month. Emphasized cross-architecture profiling, efficient buffer handling, and clean code changes.
Concise monthly performance summary for 2025-04 across fbthrift and FBGEMM, focusing on features delivered, bugs fixed, overall impact, and technologies demonstrated. Achieved architecture-aware optimizations, reduced latency, and higher throughput with stable builds across ARM (aarch64) and x86, driving faster model inference and more efficient serialization.
Concise monthly performance summary for 2025-04 across fbthrift and FBGEMM, focusing on features delivered, bugs fixed, overall impact, and technologies demonstrated. Achieved architecture-aware optimizations, reduced latency, and higher throughput with stable builds across ARM (aarch64) and x86, driving faster model inference and more efficient serialization.
Monthly performance summary for 2025-03: - Delivered targeted hardware and software optimizations across RocksDB and ROCm/FBGEMM that improved throughput, reliability, and OSS portability, enabling more efficient ML workloads on mainstream CPU architectures. - Highlights include ARM Linux CRC32c acceleration and KleidiAI acceleration with SVE-based throughput improvements, along with stability fixes for static builds and improved NaN handling.
Monthly performance summary for 2025-03: - Delivered targeted hardware and software optimizations across RocksDB and ROCm/FBGEMM that improved throughput, reliability, and OSS portability, enabling more efficient ML workloads on mainstream CPU architectures. - Highlights include ARM Linux CRC32c acceleration and KleidiAI acceleration with SVE-based throughput improvements, along with stability fixes for static builds and improved NaN handling.
February 2025: Delivered targeted performance and maintainability improvements in two key repos. In faiss, removed an unused quad_lanes variable in distance_four_codes_sve_for_small, reducing warnings and improving maintainability (commit 1fe8b8b5f13bc952db1df1df77cda1446e61f7d5, message Remove unused variable (#4205)). In ROCm/FBGEMM, added a Quantize benchmark to evaluate Fused8BitRowwiseQuantizedSBFloatToFloatOrHalf (commit aea764e515d9ff5713567088071076718e435d30, 'Add Quantize benchmark (#3706)'), and implemented ARM NEON optimizations for downcasting and integrated NEON-optimized transpose kernels (commits 3de67745166e26e9076fbdd424545c59d6520e0f, 'Add NEON implementation of Fused8BitRowwiseQuantizedSBFloatToFloatOrHalf (#3707)' and 69879dff3d29f7b3c1f912c3b15ddef09d4710ad, 'Pull ARM's matrix transpose PR (#3660)'). These changes yield significant speedups in downcasting and overall quantization/dequantization throughput on ARM.
February 2025: Delivered targeted performance and maintainability improvements in two key repos. In faiss, removed an unused quad_lanes variable in distance_four_codes_sve_for_small, reducing warnings and improving maintainability (commit 1fe8b8b5f13bc952db1df1df77cda1446e61f7d5, message Remove unused variable (#4205)). In ROCm/FBGEMM, added a Quantize benchmark to evaluate Fused8BitRowwiseQuantizedSBFloatToFloatOrHalf (commit aea764e515d9ff5713567088071076718e435d30, 'Add Quantize benchmark (#3706)'), and implemented ARM NEON optimizations for downcasting and integrated NEON-optimized transpose kernels (commits 3de67745166e26e9076fbdd424545c59d6520e0f, 'Add NEON implementation of Fused8BitRowwiseQuantizedSBFloatToFloatOrHalf (#3707)' and 69879dff3d29f7b3c1f912c3b15ddef09d4710ad, 'Pull ARM's matrix transpose PR (#3660)'). These changes yield significant speedups in downcasting and overall quantization/dequantization throughput on ARM.
Month: 2025-01 — Facebook Folly (facebook/folly) Key features delivered: - Search Algorithm Performance Optimization (F14Table): Hoisted needle vectorization out of loops in findImpl and findMatching to reduce redundant operations and improve performance on AMD64 and aarch64. Commit: 05ef75aa95b8a8bbb4e342bf6218ca102b75dee1 - CRC32 NEON Intrinsics Optimization: Replaced inline assembly with compiler intrinsics for CRC32 NEON, enabling better compiler optimizations and expected 10%+ performance gains on ARM. Commit: c61540db582fddcf63a313547b00186408cbb0f2 Major bugs fixed: - No major bugs fixed reported in this dataset for the month. Overall impact and accomplishments: - These optimizations reduce CPU cycles in hot paths (pattern matching and CRC32) and improve cross-architecture performance parity for Folly on AMD64 and ARM, contributing to higher throughput and lower latency in production workloads. Technologies/skills demonstrated: - C++ performance optimization, SIMD/vectorization strategies, ARM NEON intrinsics, cross-architecture optimization, performance profiling and analysis.
Month: 2025-01 — Facebook Folly (facebook/folly) Key features delivered: - Search Algorithm Performance Optimization (F14Table): Hoisted needle vectorization out of loops in findImpl and findMatching to reduce redundant operations and improve performance on AMD64 and aarch64. Commit: 05ef75aa95b8a8bbb4e342bf6218ca102b75dee1 - CRC32 NEON Intrinsics Optimization: Replaced inline assembly with compiler intrinsics for CRC32 NEON, enabling better compiler optimizations and expected 10%+ performance gains on ARM. Commit: c61540db582fddcf63a313547b00186408cbb0f2 Major bugs fixed: - No major bugs fixed reported in this dataset for the month. Overall impact and accomplishments: - These optimizations reduce CPU cycles in hot paths (pattern matching and CRC32) and improve cross-architecture performance parity for Folly on AMD64 and ARM, contributing to higher throughput and lower latency in production workloads. Technologies/skills demonstrated: - C++ performance optimization, SIMD/vectorization strategies, ARM NEON intrinsics, cross-architecture optimization, performance profiling and analysis.
December 2024 performance-focused month. Delivered two ARM/64-bit optimizations with measurable impact across ROCm/FBGEMM and fbthrift. Key features: 1) SVE-Accelerated Transpose for ARM Floating-Point Matrices in ROCm/FBGEMM, introducing SVE kernels and integration into the transpose path. 2) Varint Write Path Performance Optimization (AArch64) in facebook/fbthrift, refactoring writeVarintSlow into a loop with 1%–25% throughput gains. No explicit bug fixes logged in this period; the focus was on feature delivery and performance improvements that drive business value. Impact: improved throughput for ARM-based ML workloads (matrix transposition) and serialization workloads, enhancing hardware utilization and service scalability. Technologies demonstrated: SVE, ARM/vectorization, AArch64, low-level C++ performance tuning, kernel-level optimization, cross-repo collaboration.
December 2024 performance-focused month. Delivered two ARM/64-bit optimizations with measurable impact across ROCm/FBGEMM and fbthrift. Key features: 1) SVE-Accelerated Transpose for ARM Floating-Point Matrices in ROCm/FBGEMM, introducing SVE kernels and integration into the transpose path. 2) Varint Write Path Performance Optimization (AArch64) in facebook/fbthrift, refactoring writeVarintSlow into a loop with 1%–25% throughput gains. No explicit bug fixes logged in this period; the focus was on feature delivery and performance improvements that drive business value. Impact: improved throughput for ARM-based ML workloads (matrix transposition) and serialization workloads, enhancing hardware utilization and service scalability. Technologies demonstrated: SVE, ARM/vectorization, AArch64, low-level C++ performance tuning, kernel-level optimization, cross-repo collaboration.
Concise monthly summary for 2024-11 focusing on key accomplishments, major fixes, impact, and skills demonstrated across repositories facebook/fbthrift and ROCm/FBGEMM.
Concise monthly summary for 2024-11 focusing on key accomplishments, major fixes, impact, and skills demonstrated across repositories facebook/fbthrift and ROCm/FBGEMM.

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