February 2026: Delivered Legacy GPU Compatibility Enhancement for AliceO2, restoring support for older GPU architectures and tuning parameters to improve compatibility and performance on legacy hardware across architectures such as TAHITI, TESLA, FERMI, PASCAL, and KEPLER. No major bugs fixed this month. Overall impact: extended hardware support, smoother operation on legacy clusters, and preserved value for users with older GPUs. Technologies/skills demonstrated: GPU parameter tuning, cross-architecture compatibility, commit-driven development, and collaboration within the AliceO2 repository.

January 2026 (2026-01) was focused on extending GPU support, stabilizing GPU workflows, and improving visibility for QA across two repositories. The work enabled broader hardware compatibility, cleaner build configuration, more robust runtime behavior, and enhanced visual diagnostics, delivering measurable business value in performance, reliability, and developer efficiency.

December 2025 — AliceO2 GPU-focused delivery and stabilization. Delivered robust GPU tracking fixes, enhanced QA analytics, expanded CUDA architecture compatibility in RTC runtime, and comprehensive code quality improvements. These changes reduce runtime errors, improve traceability, enable broader hardware deployment, and strengthen test stability across the GPU stack.

November 2025 highlights for AliceO2Group/AliceO2: Focused on stabilizing GPU-based tracking, expanding protection controls, and strengthening QA and maintainability. Delivered feature-rich GPU TPC protection enhancements, fixed critical calculation and bounds issues, expanded QA capabilities and plots, and improved code quality, build configurability, and debugging support. These changes improve data quality, reduce runtime errors, and enhance developer productivity and external integrations.

October 2025: Delivered major GPU workflow improvements and TPC processing stability across AliceO2 and alidist, with a strong emphasis on business value through clearer configuration, enhanced debugging, memory safety, and performance tuning. Key outcomes include cleaner TPC workflow configuration and clearer compressed-cluster I/O options, expanded GPU workflow capabilities for filtered outputs and robust diagnostics, memory management optimizations and thread-safety improvements, and targeted benchmarking/debugging enhancements. Cross-repo alignment also improved HIP GPU type detection to ensure correct compilation targets.

September 2025 focused on stabilizing and accelerating GPU-based TPC tracking, improving data quality, reliability, and build modernization. Key outcomes include core enhancements to the GPU TPC tracking merger with deterministic linking, reliability improvements via enhanced debugging and sanity checks, and controlled data output plus error handling. Build-system modernization targets newer CUDA architectures to leverage recent hardware.

August 2025 monthly summary focusing on GPU-enabled work across AliceO2 and alidist, with emphasis on build reliability, runtime stability, and configurability of GPU pipelines. The month delivered significant toolchain hardening, reliability improvements in QA pipelines, and enhanced maintainability for GPU code paths, aligning development with production needs.

July 2025 highlights across three repositories (AliceO2Group/AliceO2, alisw/alidist, AliceO2Group/O2DPG) focused on GPU reliability, performance, and developer experience. Delivered a coherent set of features and stability fixes that improve end-to-end GPU workflows, validation, and cross-environment execution. Key features delivered: - GPU Standalone CI and Build Environment Improvements (commits e629c0a34361a178a722b1ed56a15f2aaf10a2a2; ab99262d3197ddf2d66fd1a7e68f022683e56d27; 2a7442d525a673398d5f972b9ca3267f90101c40): test builds without ROOT/VC/FMT/ONNX, build event display, and support for Vulkan/Wayland frontends in the new build container, reducing external dependencies and broadening GPU validation. - GPU QA: Normalize cluster counts and configurability (commits 9fa8cf58b183291ca50ac46f19c23105a4787879; d9d6894dc2b8990a93444ec7a1dbcc9307502f6e; 28d2dc3ceba7767be7e318ea6acca2cfa0152a0f): add correctly attached non-fake normalized cluster counts; separate counts for non-fake vs all tracks; make cluster cuts configurable with adjustable defaults. - GPU Display: Robustness and UX improvements (commits 52abf75ebad4f6f2f1f52918abb09e078fd74600; 8fffdd7e98431f70f58cea4aa8f9f43910f53c0f; b181f34cae0e5656a6f4abd6a32d737358a6ba5f; 7b966cddbe779645ef37b1a8f7348fac52fe61b1; bfac9ed1ba054c5b009a0a8c4d0a74f55fcc80bd; f47c6b7a684307874620a1e4d8dcee465ff1e00d; 2aa7c77507908be8c87705d346b416fdabbb701f): block until display starts, print meaningful info messages, speed up rendering for clusters with many collisions, on-demand track extrapolation, support for 'none' frontend/backend, skip rejected clusters in looper drawing, and improved timing messages. - GPU TPC Core enhancements and optimizations (commits 0e9df6ce4f047bad409fceb232650a30b0865145; 990d2070c79f3dfd8f8f8924be38082dc2ffb084; 21a985f98fc92f3dcc2d3187cfe56369782a0b31; 47f2193ca90a31465291e33edfc1fad44f3c4b59; 32df13a54a734e4ff2fdb06a6fa10b292f03bd57; 8fbde5eb87cdaa5b67ef926a2366e6aed6c56867; 26ba4abda081cbbd27176f5848518dc8feb8c604; 580dbe8d996a71b9428668a63ac2ca1871f4da94; cd0514393b6f45036244badf1bc2a1637e20ef62; abee5217de95dcb04d0cd41452c222faf70b4cb7; 7b9388d34b26c4a09eaed19533ce34e06ee66f7b): significant architectural changes such as separate looper cluster attachment kernel, keeping legs as individual segments during refits, reordering legs, storing leg IDs, reducing nclusters to 16 bits, improving cluster sorting, and refining inner SectorRefit parameters for odd legs. - DPL Workflow and coding hygiene: serialization mitigation and rule fixes (commits fd6d4eb302df34cb4d97ac8bb2ea74874b439958; 84dd75dff552f74be128232ffefda1cb574e85a3): switch to full serialization for MI100 async workflows; address a coding rule violation; and related cleanups. - Cross-repo tooling and feature detection in alidist: GPU feature detection improvements and build-time dependency tooling (commits cc6396ec1a731c90852c571ff5f13184353b1df5; f0d33435fb554dbb2921362aba7ee60c6708525c; 16bd710a2e21d519c5605581294639cd79ac9919; 83270bc61ccacab66f28a9cb2480fb737132ead5; 816a0bdcc757f2c525368aab4e58064e9f09027c); including build_requires, modulefile generation, and CUDA RTC testing. - O2DPG unified asynchronous reconstruction configuration: cross-environment alignment including NERSC (commits dd85564c13e5f62144b550562d7472e05f5164d8; 407e642f65f51b1f4c36d69aeae72873c929692c). Major bugs fixed: - Corrected usage patterns and stability: OpenGL backend uses nullptr instead of 0; DMA transfer type checks with memory registration disabled; Vulkan version check typo; shm segment mlock logic for deployment workflow; script cleanup logic; environment thread default typo; deprecated fmt::localtime usage in TPC; various display-related resets and warning suppressions; and a number of code quality and rule-violation fixes (examples: 53be5c459c07a60bcc…; dfd37f923994aef7a4…; 678b1ae8cb1592f5511…; 664d682cbd5d7edc89…; c1b57b102085a926f…; bbb5bb8e7405dda6…). - Reversion of gpu-system build tooling changes where appropriate (6be3da2ca97e38319c5ddb29c31ca6c5b34c3579) to stabilize build workflows. - GPU Display: Fix ResetScene behavior to ensure correct collision visualization (cf749eb33aa4707479466507a961a42bf41d997a).

June 2025 monthly summary for GPU-focused development across AliceO2 and alidist. The team delivered substantial improvements to CI reliability, build cleanliness, and GPU workflow configurability, while eliminating legacy code and tightening integration with the GPU stack. Key features delivered emphasized across repos: - GPU Standalone CI and Benchmark Enhancements: Added standalone CI script, enforced CI failure on errors, -Werror in standalone builds, and optimized the standalone benchmark by skipping warmup iterations during debugging. Representative commits: d22033cb4f8f91670ce89a19c8ae24a63f2c9409; 69bdaa0fc1857aa177529ca4f6c87ba46888e034; 6c537d744bd933e32baee2a0a6795e3ca5093aa1; 5ef3da96782ef0bdb971a23c245bedd8e407603e. - Build system and CMake cleanups: Introduced versioning for FindO2GPU, switched to GPU_TARGETS, and suppressed deprecation warnings for architectures, improving future maintenance and compatibility. Commits include 0c08a1f19cd74ff540088d3438688f6170d9af3a; d4fb131cbd800bc825034264d89fed32ce2a578a; fe8111b67df30bbec6be873c5bd221a724b1ae91. - Cleanup of obsolete GPUCA code: Removed several obsolete controls and classes to reduce technical debt and risk in ongoing GPU code paths. Commits: 54e61bf02df939c8e54bf2447fa71c15da03a74b; 1250d5e8c6aa21dac259189bf7928e4f7e511c01; 5b6fccc8b8d331205d1f60b0031717ec597ad726; 74db0b59fd7e17ab5cc322b7bc101e8621ae785f. - Standalone tuning and O2 settings: Added additional O2 settings for standalone benchmark to enable finer performance tuning. Commit: b0a856379ccf01cbb8cf5ec7ddb6f4cad939c1ca. - Incremental builds and CI workflow in alidist: Enabled incremental build sourcing, added standalone benchmark builds in CI, and configurable GPU standalone CI variable for better control. Commits: 6b057a67a4faea24752d84653b90f4b810b47466; fabf44f2311afff6253fbe46a7a448b8f99f607b; ef31a71c9d3c77c8d2d5c78b57e1124147f91f95. - GPU event display toggle: Added environment variable to disable the GPU event display during configuration. Commit: 1f86b787042eeed6be86eb5c84d2d47cd72f3611. Major bugs fixed: - Suppressed NaN warnings and hid NaN code path when using -ffast-math, reducing noisy build warnings. Commit: 89020a5507b53590af46a214f3f4902c89b7eabb; ad782f93a74ca0d35c0ce31a1896ea0e27a64c24. - Improved ROOT compatibility by hiding Vc correctly, preventing exposure of internal types in ROOT builds. Commit: d50b3b029cab92906d63d4714ebd3c8af68d9978. - Fixed decompressTPCFromROOT option handling in GPUWorkflow to avoid misconfiguration. Commit: de3063cf8200c0e83b353f417578eeb0bf6b99c6. - Vulkan loader compatibility: Switched to a one-argument loader to improve cross-implementation compatibility. Commit: d493ded804afcecf95e45565bfca0b48352f7300. - Added build option to disable building the display to simplify configurations and reduce build times where display is not required. Commit: e2a6098acc7dc7bc1c9c48d76ff9dbc1d4732726; 4f406ccad4cafa9afc201cda81b9232a2bd517c8. - Guarded GPU workflows against unnecessary MC label requests when TPC tracking is disabled, avoiding redundant data processing. Commit: bef11c6b01f476c798e763a011f18fb2295fd67d. - Fixed typo in event dump file naming to avoid mislabeling and downstream confusion. Commit: ece12c56cf83a7be9e4b92d8c1b7721820b0aef9. - Other improvements to ignore fake tracks in clone track computation and to ensure readers are not added unintentionally in gpu-reco-workflow. Commits: b71ab71489436b1d57c807d6a04557b0eb4a6f7a; 269941bd68af8bbd1d72ab48569867ddc55686eb. Overall impact and accomplishments: - Increased reliability, reproducibility, and performance visibility of GPU builds and benchmarks across AliceO2 and alidist, enabling faster validation and safer production deployments. - Reduced maintenance burden by eliminating obsolete GPUCA code paths and modernizing the build configuration, aligning with alidist-driven workflows and enabling broader GPU feature testing. - Enhanced configurability and scalability for CI, including incremental builds and standalone benchmarking, supporting faster iteration cycles and more targeted GPU feature validation. Technologies and skills demonstrated: - Advanced CMake usage and project configuration (GPU_TARGETS, FindO2GPU versioning, deprecation warnings handling) - CI/CD best practices (standalone CI, -Werror, fail-on-errors, conditionally running benchmarks) - GPU workflow tuning and performance benchmarking (O2 settings, standalone benchmarking, skip-warmup optimization) - Dependency hygiene and codebase cleanup (removal of obsolete GPUCA code) - Cross-repo collaboration patterns (AliceO2 and alidist integration, environment-driven configuration) Notes: This summary highlights the June 2025 activities and can be used for performance reviews, stakeholder updates, and project retrospectives.

May 2025 monthly summary focusing on GPU determinism, debugging, and modernization across AliceO2/AliceO2Physics. Highlights include deterministic mode enhancements for GPU sorting and cluster handling, build/config/constexpr support, performance optimizations avoiding unnecessary dEdx computation, robust multi-GPU debugging tools, and substantial codebase modernization and build-system improvements.

April 2025 summary: Stabilized GPU platforms, modernized the build system, and expanded hardware support across the AliceO2Group repository family. Key outcomes include a cleaned and correctness-verified GPU core, a revamped GPU parameterization framework with runtime parameters and defaults, and an improved CMake workflow that reduces build friction and suppresses architecture-related warnings. Added ONNXRuntime integration with portable GPU feature detection enabling conditional builds for CUDA/ROCm/Metal backends, and implemented memory allocation improvements alongside TPC enhancements to boost runtime efficiency and memory safety. Documentation updates and workflow reliability fixes support faster feature delivery and easier maintenance. Overall impact: reduced maintenance burden, faster delivery of GPU-focused features, and improved multi-hardware support. This lays groundwork for future performance tuning, portability, and scalable CI processes.

In March 2025, across AliceO2Group/AliceO2, AliceO2Group/O2DPG, and alisw/alidist, the team delivered focused GPU and build-system improvements, automation enhancements for MI100 runtime handling, and deterministic execution features, complemented by targeted bug fixes. The work elevated stability, reproducibility, and performance across GPU workflows, streamlined build configuration for ROCm/OpenCL, and enhanced data quality and QC accessibility in production runs. Key features delivered: - GPU code quality and CAMath improvements: enhanced NaN handling, suppression of bogus warnings, kernel path cleanup, and CAMath/Math helper enhancements. - GPU Build-system cleanup and obsolete-option removals: LLVM version bump for OpenCL compatibility, removal of hipcc in HIP builds, and elimination of obsolete preprocessor tricks. - MI100 workaround automation in dpl-workflow: automatic application of MI100 workaround in both synchronous and asynchronous paths. - GPU RTC deterministic mode and launch-bounds tooling: added deterministic mode, launch-bounds tooling, and runtime loadable parameter objects for reproducible runs. Major bugs fixed: - GPU TPC: Fix filtering check (#14032) to address correctness in the GPU TPC path. - DPL data validation and track-merging synchronization: improved handling to report bogus data, allow earlier marker insertion, and enhance synchronization during track merging. Overall impact and accomplishments: The March sprint delivered more deterministic, robust GPU workloads with cleaner build configurations, enabling faster iteration and more reliable production deployments. The MI100 workflow automation and RTC determinism contribute to reproducible performance across heterogeneous hardware, while targeted bug fixes reduce runtime surprises in production campaigns. Technologies/skills demonstrated: - GPU programming and CAMath/Math portability, including constexpr usage and NaN handling. - Build-system modernization with CMake, ROCm/OpenCL compatibility, and cross-repo config management. - Performance and reliability engineering: device-side sorting, deterministic kernels, and launch-bounds tooling. - Debugging and quality assurance: robust QA improvements and error handling in GPU frameworks, plus improved synchronization techniques.

February 2025 performance and accomplishments summary focusing on GPU-centric modernization, performance optimizations, and build/tooling improvements across AliceO2Group/AliceO2, O2DPG, alisw/alidist, and JuliaGPU/pocl. Highlights include extensive GPU code cleanup and modernization, host-memory parallelism, migration to TBB, build-system hardening for GCC 14 and CMake 3.31, and expanded SPIR-V support and compatibility improvements. Cross-repo enhancements improved stability, portability, and business value by enabling faster development cycles and more reliable GPU deployments.

January 2025 (Month: 2025-01) across AliceO2Group/AliceO2 and alisw/alidist: delivered substantial GPU OpenCL modernization, build/tooling cleanup, and reliability improvements. Consolidated the OpenCL path into a single implementation, stabilized data transfer and CPU/GPU mode behavior, and tightened observability and code quality. The work reduces maintenance burden, accelerates future feature work, improves build determinism, and enhances runtime reliability for end-to-end GPU processing.

November 2024 focused on stabilizing GPU workflows, enabling better configurability, and improving build hygiene. Key wins in AliceO2 include robust GPU header handling, exit-code forwarding fixes for double-pipelined processing, and a split NDPiecewisePolynomials to avoid ROOT headers in device code. We introduced time-bin utilities and a max-time-bin derivation helper, added per-TF NHbf configurability, and provided an empty streaming operator for SMatrixGPU to support debugging workflows. On the integration side, we forced the correct number of orbits in FST gpu-reco and exposed configurable lanes/threads for TPC IDC in the calibration workflow, boosting throughput and stability. OpenCL workflow improvements and GPU data-type consolidation further simplified maintenance and portability.

Month: 2024-10 — Summary of key engineering outcomes across two repositories. Delivered targeted bug fixes that improve workflow reliability and cross-architecture build readiness, enabling more accurate PbPb data processing and broader hardware support for GPU benchmarking.