Abstracts of Invited Talks
 

Analyzing Massive Social Networks using Multicore and Multithreaded Architectures
Wednesday, March 17, 20:15h-21:15h
David A. Bader, Georgia Institute of Technology, USA

Emerging real-world graph problems include detecting community structure in large social networks, improving the resilience of the electric power grid, and detecting and preventing disease in human populations.  Unlike traditional applications in computational science and engineering, solving these problems at scale often raises new challenges because of sparsity and the lack of locality in the data, the need for additional research on scalable algorithms and development of frameworks for solving these problems on high performance computers, and the need for improved models that also capture the noise and bias inherent in the torrential data streams.  The explosion of real-world graph data poses a substantial challenge: How can we analyze constantly changing graphs with billions of vertices?  Our approach leverages the Cray XMT's fine-grained parallelism and flat memory model to scale to massive graphs.  On the Cray XMT, our static graph characterization package GraphCT summarizes such massive graphs, and our ongoing STINGER streaming work updates clustering coefficients on massive graphs at a rate of tens of thousands updates per second.

Short Bio of David A. Bader:
David A. Bader is a Full Professor in the School of Computational Science and Engineering, College of Computing, at Georgia Institute of Technology.  Dr. Bader has also served as Director of the Sony-Toshiba-IBM Center of Competence for the Cell Broadband Engine Processor.  He received his Ph.D. in 1996 from The University of Maryland, was awarded a National Science Foundation (NSF) Postdoctoral Research Associateship in Experimental Computer Science.  He is an NSF CAREER Award recipient, an investigator on several NSF and NIH awards, was a distinguished speaker in the IEEE Computer Society Distinguished Visitors Program, and a member of the IBM PERCS team for the DARPA High Productivity Computing Systems program.  Dr. Bader serves on the Research Advisory Council for Internet2, the Steering Committees of the IPDPS and HiPC conferences, and is the General Chair of IPDPS 2010 and Chair of SIAM PP12.  He is an associate editor for several high impact publications including the ACM Journal of Experimental Algorithmics (JEA), IEEE DSOnline, and Parallel Computing, has been an associate editor for the IEEE Transactions on Parallel and Distributed Systems (TPDS), is an IEEE Fellow and a Member of the ACM. Dr. Bader's interests are at the intersection of high-performance computing and computational biology and genomics.  He has co-chaired a series of meetings, the IEEE International Workshop on High-Performance Computational Biology (HiCOMB), co-organized the NSF Workshop on Petascale Computing in the Biological Sciences, written several book chapters, and co-edited special issues of the Journal of Parallel and Distributed Computing (JPDC) and IEEE TPDS on high-performance computational biology. He has co-authored over 100 articles in peer-reviewed journals and conferences, and his main areas of research are in parallel algorithms, combinatorial optimization, and computational biology and genomics.
 

MareIncognito: A Perspective Towards Exascale
Thursday, March 18, 9:00h -10:00h
Jesus Labarta, Barcelona Supercomputing Centre, Spain

MareIncognito is a cooperative project between IBM and the Barcelona Supercomputing Center (BSC) targeting the design of relevant technologies on the way towards exascale. The initial challenge of the project was to study the potential design of a system based on a next generation of Cell processors. Even so, the approaches pursued are general purpose, applicable to a wide range of accelerator and homogeneous multicores and holistically addressing a large number of components relevant in the design of such systems.
The programming model is probably the most important issue when facing the multicore era. We need to offer support for asynchronous data flow execution and decouple the way source code looks like and the way the program is executed and its operations (tasks) scheduled. In order to ensure a reasonable migration path for programmers the execution model should be exposed to them through a syntactical and semantic structure that is not very far away from current practice. We are developing the StarSs programming model which we think addresses some the challenges of targeting the future heterogeneous / hierarchical multicore systems at the node level. It also integrates nicely into coarser level programming models such as MPI
and what is more important in ways that propagate the asynchronous dataflow execution to the whole application. We are also investigating how some of the features of StarSs can be integrated in OpenMP.
At the architecture level, interconnect and memory subsystem are two key components. We are studying in detail the behavior of current interconnect systems and in particular contention issues. The question is to investigate better ways to use the raw bandwidth that we already have in our systems and can expect to grow in the future. Better understanding of the interactions
between the raw transport mechanisms, the communication protocols and synchronization behavior of applications should lead to avoid an exploding need for bandwidth that is often claimed. The use of the asynchronous execution model that StarSs offers can help in this direction as a very high overlap between communication and computation should be possible. A similar
effect or reducing sensitivity to latency as well as the actual off chip bandwidth required should be supported by the StarSs model.
The talk will present how we target the above issues, with special details on the StarSs programming model and the underlying idea of the project of how tight cooperation between architecture, run time, programming model, resource management and application are needed in order to achieve in the future the exascale performance.
 

The Natural Parallelism
Friday, March 19, 9:00h-10:00h
Robert Strzodka, MPI Informatik, Saarbruecken, Germany

With the advent of multi-core processors a new unwanted way of parallel programming is required which is seen as a major challenge. This talk will argue in exactly the opposite direction that our accustomed programming paradigm has been unwanted for years and parallel processing is the natural scheduling and execution model on all levels of hardware.
Sequential processing is a long outdated illusionary software concept and we will expose its artificiality and absurdity with appropriate
analogies of everyday life. Multi-core appears as a challenge only when looking at it from the crooked illusion of sequential processing. There are other important aspects such as specialization or data movement, and admittedly large scale parallelism has also some issues which we will discuss. But the main problem is changing our mindset and helping others to do so with better education so that parallelism comes to us as a friend and not enemy.

Short Bio of Robert Strzodka:
 Robert Strzodka is the head of the research group Integrative Scientific Computing at the Max Planck Institute for Computer Science in Saarbrücken since 2007. His research focuses on efficient interactions of mathematic, algorithmic and architectural aspects in heterogeneous high performance computing. Previously, Robert was a visiting assistant professor in computer science at the Stanford University and until 2005 a postdoc at the Center of Advanced European Studies and Research in Bonn. He received his doctorate in numerical mathematics from the University of Duisburg-Essen in 2004.