The 2012 biennial high performance workshop in Cetraro, Italy, focused on the challenges facing the computing research community to reach exascale performance in the next decade. The contributions illustrated the wish to achieve this feat but also revealed a need for a coordinated strategy to develop, deploy and program exascale systems. The papers in this book are arranged into four major topics: energy, scalability, new architectural concepts and programming of heterogeneous computing systems.
Chapter 1 introduces the status of present supercomputers. The fastest computers today are still about two orders of magnitude separated from the exascale mark. It turns out that the exascale challenges require a rethinking of computing systems at all levels: hardware, software, algorithms and their interaction.
Energy demands are a major limiting factor of today's fastest supercomputers. In Chapter 2 it is argued that the next quantum leap in performance will require a shift in architectures and technology to achieve the 20MW target for exascale computing. Energy saving data caches are proposed to minimize the memory subsystem power consumption.
Grand computational problems will run on millions of cores. In Chapter 3 scalable compute paradigms for dense linear algebra on massive heterogeneous systems are presented. Scalability also implies new strategies for fast synchronization between cooperating threads running at different levels of the hardware hierarchy.
Architectural concepts are presented in Chapter 4. Data centric computing and blending of an algorithm with the architecture requires a new vision on hardware/ software co-design and its impact on communication.
Finally, Chapter 5 addresses programming heterogeneous systems. The challenge is to create a uniform programming environment capable of unleashing the maximal performance from accelerators and multicores. A uniform environment allows tuning a program to harvest the benefits of all parallel hardware.
The editors thank the authors for their high-quality research leading to a collection of papers presenting a balanced perspective on the transition of high performance computing towards exascale computing.
Special thanks go to the reviewers for their expert assistance and valuable suggestions.
We are especially grateful to Maria Teresa Guaglianone for her efficient management of the manuscripts and extensive communication with reviewers, editors and authors.
Erik D'Hollander, Belgium
Jack Dongarra, USA
Ian Foster, USA
Lucio Grandinetti, Italy
Gerhard Joubert, Netherlands/Germany
12 July 2013