9-13 July 2018
Sofia, Bulgaria
Europe/Sofia timezone

I/O in the ATLAS multithreaded framework

10 Jul 2018, 11:00
15m
Hall 3 (National Palace of Culture)

Hall 3

National Palace of Culture

presentation Track 5 – Software development T5 - Software development

Speaker

Jack Cranshaw (Argonne National Laboratory (US))

Description

Scalable multithreading poses challenges to I/O, and the performance of a thread-safe I/O strategy
may depend upon many factors, including I/O latencies, whether tasks are CPU- or I/O-intensive, and thread count.
In a multithreaded framework, an I/O infrastructure must efficiently supply event data to and collect it from many threads processing multiple events in flight.
In particular, on-demand reading from multiple threads may challenge caching strategies that were developed for serial processing and may need to be enhanced.
This I/O infrastructure must also address how to read, make available, and propagate in-file metadata and other non-event data needed as context for event processing.

We describe the design and scheduling of I/O components in the ATLAS multithreaded control framework, AthenaMT, for both event and non-event I/O.
We discuss issues associated with exploiting the multithreading capabilities of our underlying persistence technology, ROOT,
in a manner harmonious with the ATLAS framework’s own approach to thread management.
Finally, we discuss opportunities for evolution and simplification of I/O components that have successfully supported ATLAS event processing for many years
from their serial incarnations to their thread-safe counterparts.

Primary authors

Peter Van Gemmeren (Argonne National Laboratory (US)) David Malon (Argonne National Laboratory (US)) Jack Cranshaw (Argonne National Laboratory (US)) Marcin Nowak (Brookhaven National Laboratory (US))

Presentation Materials