Real-time use of GPUs in NA62 experiment

We describe a pilot project for the use of GPUs in a real-time triggering application in the early trigger stages at the CERN NA62 experiment, and the results of the first field tests together with a prototype data acquisition (DAQ) system. This pilot project within NA62 aims at integrating GPUs into the central L0 trigger processor, and also to use them as fast online processors for computing trigger primitives. Several TDC-equipped sub-detectors with sub-nanosecond time resolution will participate in the first-level NA62 trigger (L0), fully integrated with the data-acquisition system, to reduce the readout rate of all sub-detectors to 1 MHz, using multiplicity information asynchronously computed over time frames of a few ns, both for positive sub-detectors and for vetos. The online use of GPUs would allow the computation of more complex trigger primitives already at this first trigger level. We describe the architectures of the proposed systems, focusing on measuring the performance (both throughput and latency) of various approaches meant to solve these high energy physics problems. The challenges and the prospects of this promising idea are discussed.