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    Alice Weekly Meeting: Software for Hardware Accelerators

    → Europe/Zurich
    ALICE GPU Meeting
    Zoom Meeting ID
    61230224927
    Host
    David Rohr
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      • 10:00 → 10:20
        Discussion 20m
        Speaker: David Rohr (CERN)

        Color code: (critical, news from this week: blue, news from last week: purple, no news: black)

        Sync reconstruction

         

        Async reconstruction

        • Need to investigate short GPU stall problem.
        • Limiting factor for pp workflow is now the TPC time series, which is to slow and creates backpressure (costs ~20% performance on EPNs). Enabled multi-threading as recommended by Matthias - need to check if it works.
        • Will tune existing 16-core settings, add a SITEARCH for 16core CPU, and 16coreCPU + generic NVIDIA / AMD GPU, like for 8 core.
        • Will retune EPN async workflow for TPC + ITS on GPU on 2025 data.

         

        GPU ROCm / compiler topics:

        • Problem with building ONNXRuntime with MigraphX support.
        • Need to find a way to build ONNXRuntime with support for CUDA and for ROCm.
        • Try to find a better solution for the problem with __device__ inline functions leaking symbols in the host code.
        • All gpu-ci related issues fixed, it is now compiling for the correct architectures and it is green.
        • Added OpenCL build to gpu-system.sh in build mode.
        • ROCm 10.1 seems as good as ROCm 10 on MI50.
        • SLC10-FullCI added by Giulio/Vit: currently failing since gpu-system's build option does not provide CUDA stub libraries, if we don't bring host libraries to the container. Need to check how to fix it without colliding if we bring host libraries tot he container.
        • Bumped to CUDA 13.4 and ROCm 10.1, we can now bump to GCC 16.2.1

         

        TPC / GPU Processing 

        • WIP: Use alignas() or find a better solution to fix alignment of monte carlo labels: https://its.cern.ch/jira/browse/O2-5314
        • Need to check the problem with ONNX external memory allocator.
        • Next high priority topic: Improvements for cluster sharing and cluster attachment at lower TPC pad rows. PR: https://github.com/AliceO2Group/AliceO2/pull/14542
        • Check for unnecessary f64 instructions in GPU code.
        • Added CPUDevice backend for debugging (Runs on CPU, but in the way we normally run on the device).

         

        Other topics:

        • GCC bump - Status?

         

        EPN GPU Topics:

        • Discuss with Ernst / Giulio how to do a build for SLC10 on EPNs with build mode.
        • Need to test Maksim's SLC9 container with ROCm included on SLC10 node, Giada fixed CVMFS for me :).
      • 10:20 → 10:25
        TPC ML Clustering 5m
        Speaker: Christian Sonnabend (CERN)
      • 10:25 → 10:30
        GPU Parameter Optimizations 5m
        Speaker: Gabriele Cimador (CERN, Università and INFN Torino)

        On vacation, no news

        Next step:

        tuning without rtc on its kernels

      • 10:30 → 10:35
        Efficient Data Structures 5m
        Speaker: Dr Oliver Gregor Rietmann (CERN)
      • 10:40 → 10:45
        TPC Clusterization / OpenCL / Highly Ionizing Particles 5m
        Speaker: Felix Weiglhofer (CERN)
      • 10:45 → 10:50
        ITS Tracking 5m
        Speakers: Felix Schlepper (CERN, Heidelberg University (DE)), Gabriele Cimador (CERN, Università and INFN Torino), Matteo Concas (CERN)

        Gabriele: on vacation, will report next week

      • 10:50 → 10:55
        System Run Coordination Topics 5m
        Speaker: Ernst Hellbar (CERN)