CERN Accelerating science

ATLAS Note
Report number	ATL-SOFT-PROC-2023-039
Title	Optimization of opportunistic utilization of the ATLAS high-level trigger farm for LHC run 3
Author(s)	Glushkov, Ivan (University of Texas at Arlington (US)) ; Di Girolamo, Alessandro (CERN) ; Walker, Rodney (Ludwig Maximilians Universitat (DE)) ; Gottardo, Carlo Alberto (CERN)
Corporate Author(s)	The ATLAS collaboration
Collaboration	ATLAS Collaboration
Publication	2024
Imprint	21 Sep 2023
Number of pages	7
In:	EPJ Web Conf. 295 (2024) 07035
DOI	10.1051/epjconf/202429507035
Subject category	Particle Physics - Experiment
Accelerator/Facility, Experiment	CERN LHC ; ATLAS
Free keywords	Sim@P1 ; HLT ; Opportunistic Cloud ; Resource Optimization ; Utilization Efficiency
Abstract	The ATLAS Trigger and Data Acquisition (TDAQ) High Level Trigger (HLT) computing farm contains 120000 cores. These resources are critical for online selection and collection of collision data in the ATLAS experiment during LHC operation. Since 2013, during longer period of LHC inactivity these resources are being used for offline event simulation via the "Simulation at Point One" project (Sim@P1). With the recent start of LHC Run 3 and the flat computing budget expected in the near future, finding ways to maximize the resource utilization efficiency is of paramount importance. Recent improvements in the ATLAS software stack can potentially allow the utilization of the Sim@P1 even during LHC operation for the duration of the LHC inter-fill gaps. While previous papers on the Sim@P1 project were emphasizing the technical implementation details, the current contribution is presenting results of a variety of tests that led to the optimal configuration of the job submission infrastructure which would allow the use of Sim@P1 during LHC Run 3.

Corresponding record in: Inspire