D7.3: Petascaling and Optimisation for Tier-1 Architectures

Work Package 7 ‘Scaling Applications for Tier-0 and Tier-1 Users’ provides medium-term petascaling and optimisation support for European HPC applications to ensure that they can make effective use of both Tier-0 and Tier-1 systems. Such applications-enabling projects typically last around six months and provide direct benefits to European researchers. Through the applications-enabling work, WP7 develops specific expertise on most, if not all, of the architectures which make up the top two tiers of the European HPC system. PRACE-1IP provided best practice guides on the PRACE Tier-0 systems that cover programming techniques, compilers, tools and libraries. PRACE-2IP supplements these with best practice guides for the other architectures which are important at Tier-1 to allow European researchers to make efficient use of these systems. PRACE-2IP Task 7.3 is called ‘Best Practice Guides for Tier-1 Architectures’. The main goal of this task is to investigate the efficient use of HPC systems, collect best practices on how to achieve good performance on the systems, and disseminate this knowledge through best practice guides. The target audience are users and support staff who are developing and enabling applications. Topics for these best practice guides include: optimal porting of applications (e.g., choice of numerical libraries and compiler options); architecture-specific optimisation and petascaling techniques; optimal system environment (e.g., tuneable system parameters, job placement and optimised system libraries); debuggers, performance analysis tools and programming environment. Task 7.3 covers a generic x86 cluster guide, six system-specific mini-guides for x86 clusters, a generic mini-guide for GPGPU-accelerated clusters, and the SuperMUC guide. The SuperMUC guide admittedly describes a Tier-0 system, however, it started in 2011 with the description of a Tier-1 system: SuperMIG, the SuperMUC migration system. Finally, because of the total size of the best practice guides, we decided not to include them as separate chapters in this report but to refer to the online versions on the PRACE RI web site instead