Aug 21 – 25, 2017
University of Washington, Seattle
US/Pacific timezone

Multithreading in the ATLAS High-Level Trigger

Aug 21, 2017, 2:40 PM
Auditorium (Alder Hall)


Alder Hall

Oral Track 1: Computing Technology for Physics Research Track 1: Computing Technology for Physics Research


Adam Edward Barton (Lancaster University (GB))


Over the next decade of LHC data-taking the instantaneous luminosity
will reach up 7.5 times the design value with over 200 interactions
per bunch-crossing and will pose unprecedented challenges for the
ATLAS trigger system.

With the evolution of the CPU market to many-core systems, both the
ATLAS offline reconstruction and High-Level Trigger (HLT) software
will have to transition from a multi-process to a multithreaded
processing paradigm in order not to exhaust the available physical
memory of a typical compute node. The new multithreaded ATLAS software
framework, AthenaMT, has been designed from the ground up to support
both the offline and online use-cases with the aim to further
harmonize the offline and trigger algorithms. The latter is crucial
both in terms of maintenance effort and to guarantee the high trigger
efficiency and rejection factors needed for the next two decades of

We report on an HLT prototype in which the need for HLT­ specific
components has been reduced to a minimum while retaining the key
aspects of trigger functionality including regional reconstruction and
early event rejection. We report on the first experience of migrating
trigger algorithms to this new framework and present the next steps
towards a full implementation of the ATLAS trigger within AthenaMT.

Primary author

Adam Edward Barton (Lancaster University (GB))

Presentation materials

Peer reviewing