Abstract
The ALICE High Level Trigger (HLT) is an online reconstruction, triggering and data compression system used in the ALICE experiment at CERN. Unique among the LHC experiments, it extensively uses modern coprocessor technologies like general purpose graphic processing units (GPGPU) and field programmable gate arrays (FPGA) in the data flow. Realtime data compression is performed using a cluster finder algorithm implemented on FPGA boards. These data, instead of raw clusters, are used in the subsequent processing and storage, resulting in a compression factor of around 4. Track finding is performed using a cellular automaton and a Kalman filter algorithm on GPGPU hardware, where both CUDA and OpenCL technologies can be used interchangeably. The ALICE upgrade requires further development of online concepts to include detector calibration and stronger data compression. The current HLT farm will be used as a test bed for online calibration and both synchronous and asynchronous processing frameworks already before the upgrade, during Run 2. For opportunistic use as a Grid computing site during periods of inactivity of the experiment a virtualisation based setup is deployed.
Highlights
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The ALICE High Level Trigger (HLT) has been successfully used throughout the LHC Run 1 as an online data reconstruction and compression facility
To cope with the higher data throughput related to this upgrade the HLT farm has been equipped with new hardware and a new networking layout has been implemented
Summary
This content has been downloaded from IOPscience. Please scroll down to see the full text. Ser. 664 082023 (http://iopscience.iop.org/1742-6596/664/8/082023) View the table of contents for this issue, or go to the journal homepage for more. Download details: IP Address: 137.138.93.202 This content was downloaded on 09/03/2016 at 07:50 Please note that terms and conditions apply. 21st International Conference on Computing in High Energy and Nuclear Physics (CHEP2015) IOP Publishing. Journal of Physics: Conference Series 664 (2015) 082023 doi:10.1088/1742-6596/664/8/082023. Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, 60438 Frankfurt, Germany
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