Users recount accomplishments on Titan while looking toward future systems
Last week the Oak Ridge Leadership Computing Facility (OLCF), a US Department of Energy (DOE) Office of Science User Facility located at DOE’s Oak Ridge National Laboratory (ORNL), held its annual user meeting—an event that centered on the OLCF’s established supercomputer as well as its new and future systems.
Some presentations during the meeting recognized achievements on the current Cray XK7 Titan supercomputer, and others homed in on the potential 200-petaflop IBM AC922 Summit. Staff also introduced the timeline for the OLCF’s future exascale supercomputer, Frontier.
One hundred and seventeen users and staff members attending the meeting recapped accomplishments on Titan over the past year, heard about the progress on applications for Summit, and learned about the OLCF’s new data services. The OLCF-hosted event took place at ORNL from May 15 to 17.
“These user meetings allow users to have one-on-one, face-to-face conversations with OLCF staff,” said Tjerk Straatsma, distinguished researcher in the National Center for Computational Sciences. “It’s always good for users to have a working relationship with the people who provide the resources, and it’s good for us to be able to learn what’s important to them as well.”
The first day focused on Titan and new accomplishments on the leadership-class system in the last year.
Brant Robertson, associate professor at the University of California–Santa Cruz, gave the first talk, titled “Extreme Simulations of Starburst-Driven Winds.” Using Titan, Robertson and Princeton University postdoctoral fellow Evan Schneider performed the largest simulations ever of supernova-driven outflows of gas from galaxies. The simulations used the Cholla hydrodynamics code written by Schneider, who gave a companion talk titled “Cholla: A GPU-Native Hydro Simulation Code for Leadership Computing.”
Supernovae—exploding stars—are already known to drive winds from galaxies, but these new simulations reveal that dense galactic winds can produce an outflow of high-density gas when they cool. These results offer novel insight into how galaxies are formed and demonstrate advances in modeling these complex phenomena.
The first day also featured a presentation about Frontier, the OLCF’s future exascale system, slated to be available to users in 2022.
On the meeting’s second day, Straatsma presented an update on the Center for Accelerated Application Readiness (CAAR) teams’ progress. CAAR’s 13 scientific application teams are working to optimize their applications efficiently on scaled-up GPU resources such as Summit.
Straatsma said all the teams are on track to meet the set criteria for running on Summit. The teams must show that the time-to-solution goes down when they scale their codes to more than 20 percent of the machine. In addition, the teams must demonstrate that they use Summit’s GPUs efficiently.
Abhishek Singharoy, assistant professor at Arizona State University, has been running the Nanoscale Molecular Dynamics (NAMD) software program, a biophysics code developed by the late Klaus Schulten at the University of Illinois with senior research programmer James Phillips, on a portion of Summit’s architecture. Singharoy’s user meeting talk, “Biomolecular Structure Determination with NAMD—Computational Cryo-EM on Titan,” highlighted that NAMD currently performs 6–10 times faster when scaled to Summit’s architecture. Singharoy aims to use Summit for ensemble calculations of smaller systems with longer, biologically relevant timescales than what is currently possible to capture using Titan.
During the meeting, users could share their experiences with Summit and their progression on the system thus far. Users who have not yet run code on the new IBM architecture took away best practices for adapting their codes.
“This year’s meeting provided an opportunity for users to talk with one another about what they have done to get ready for Summit,” Straatsma said. “It was an opportunity to find out what the environment is going to be like with this machine.”
The meeting’s final day was dedicated to talks about the OLCF’s new data services. The first talk zeroed in on how OLCF is providing a “platform as a service” capability to allow bundling and deploying data services (e.g., workflow, portal, or analysis components) as containers. This would enable researchers to create and run ancillary data services with OLCF’s resources. Another talk provided an overview of Constellation, a framework that allows users to obtain a digital object identifier (DOI) to publish scientific data artifacts for open access. A third talk focused on SIGHT, a remote visualization tool that allows for both model tuning before beginning a simulation and real-time visualization.
Two poster sessions, featuring 32 posters submitted by users and staff members, highlighted Titan and early Summit achievements.
The OLCF User Group (OUG) conducted an election during the event to fill three seats on its executive board. Schneider, ORNL’s Sarat Sreepathi, and Lawrence Berkeley National Laboratory’s Lin-Wang Wang were selected to serve terms of 3 years each. The OUG executive board is composed of 10 users who give feedback to OLCF staff on its services and represent the OLCF user community.
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