| Issue |
EPJ Web Conf.
Volume 337, 2025
27th International Conference on Computing in High Energy and Nuclear Physics (CHEP 2024)
|
|
|---|---|---|
| Article Number | 01201 | |
| Number of page(s) | 8 | |
| DOI | https://doi.org/10.1051/epjconf/202533701201 | |
| Published online | 07 October 2025 | |
https://doi.org/10.1051/epjconf/202533701201
High-throughput data distribution for online computing in the CBM experiment
1 Frankfurt Institute for Advanced Studies, Frankfurt am Main, Germany
2 Johann Wolfgang Goethe-Universität Frankfurt, Frankfurt am Main, Germany
3 GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany
* e-mail: cuveland@compeng.uni-frankfurt.de
Published online: 7 October 2025
The CBM experiment, a fixed-target heavy-ion experiment at the upcoming GSI/FAIR SIS100 facility, aims to investigate QCD at high baryon densities. The CBM First-level Event Selector (FLES) serves as the central event selection system of the experiment. It functions as a high-performance computer cluster tasked with the online analysis of physics data, including full event reconstruction, at an incoming data rate of up to 1 TB/s. The CBM detector systems operate in a free-running and self-triggered manner, delivering time-stamped data streams. Without inherent event separation, timeslice building replaces global event building. The FLES online data distribution integrates data from around 5000 input links into self-contained, overlapping processing intervals and distributes these to the compute nodes. Using a combination of RDMA and zero-copy techniques, timeslices can be built efficiently over a high-throughput InfiniBand network and distributed to available online computing resources for full online event reconstruction and analysis in a heterogeneous HPC cluster system. A new IPC online interface to timeslice data utilizes Posix shared memory governed by a referencecounting item distributor. This design combines maximum performance and flexibility with minimum memory consumption. These developments have been successfully field-tested in production at the CBM predecessor experiment mCBM at the GSI/FAIR SIS18.
© The Authors, published by EDP Sciences, 2025
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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