A publication of the Advanced Simulation & Computing Division, NA-121.2, NNSA Defense Programs
June 2009
NA-ASC-500-09—Issue 11
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New Project Team Guides Code Developers to Fully Exploit Sequoia
The massive size and capability of the 2011–2012 Sequoia system presents significant challenges to users and staff.
With the 500-teraFLOPS ASC Dawn system on the computer room floor at Lawrence Livermore National Laboratory, preparation is under way to develop software applications scaled to run on Dawn’s successor, Sequoia. Sequoia will be capable of achieving performance levels 20 to 50 times that of BlueGene/L with materials science codes, and application code teams will need guidance to succeed in fully exploiting Sequoia’s capability. The Sequoia Scalable Applications Preparation Project (SSAPP) has been initiated by Livermore Computing (LC) to develop and provide the needed guidance for code teams.
A “From Here to Sequoia” seminar was held on March 23 to kick off the SSAPP efforts. Presentations ranged from Sequoia: An IBM Perspective to Dawn ‘Getting Started’ Pointers. Among the 90+ in attendance were participants from LLNL, IBM, and Sandia, Los Alamos, Lawrence Berkeley, and Argonne national laboratories.
The Sequoia system poses new challenges for code teams. Current BlueGene/L experience informs scalability for Dawn and Sequoia, but the message passing interface (MPI) is not likely to scale to a million+ tasks for most codes, so node-level nested concurrency will be needed. The Sequoia system will follow the Moore's-Law-driven industry trend of increasing processor core counts per node. Sequoia will also feature new and innovative shared-memory programming technologies beyond traditional locks and threads models, which may offer significant performance benefits. Code teams will want to exploit these alternate means of achieving parallel performance and reducing the MPI task count. The SSAPP is intended to assist code developers with this transition.
As part of the ongoing SSAPP effort, the LC Hotline staff, the Development Environment Group, and the Training and Documentation staff are poised to provide timely information through all stages of the Sequoia project. Expertise in compilers and performance tools will be provided, and IBM experts and on-site IBM applications analysts will provide workshops, training, and application support. Documentation and training will be provided for each stage of development of Dawn and Sequoia—from system build through general availability.
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