Supervision of the ATLAS High Level Trigger System

TL;DR

This paper describes the design and implementation of a supervision system for the ATLAS High Level Trigger, demonstrating its ability to manage over 1000 processes in a large-scale particle physics experiment.

Contribution

It introduces a prototype supervision system for the ATLAS HLT, showcasing its scalability and control capabilities in a high-performance computing environment.

Findings

Supervision system successfully managed over 1000 processes.

Scalability tests confirmed effective control on 230 nodes.

Prototype implementation integrated with ATLAS Online Software.

Abstract

The ATLAS High Level Trigger (HLT) system provides software-based event selection after the initial LVL1 hardware trigger. It is composed of two stages, the LVL2 trigger and the Event Filter. The HLT is implemented as software tasks running on large processor farms. An essential part of the HLT is the supervision system, which is responsible for configuring, coordinating, controlling and monitoring the many hundreds of processes running in the HLT. A prototype implementation of the supervision system, using tools from the ATLAS Online Software system is presented. Results from scalability tests are also presented where the supervision system was shown to be capable of controlling over 1000 HLT processes running on 230 nodes.