High Performance Computing Symposium (HPC 2012) March 16, 2012 Welcome to the 2012 High Performance Computing Symposium! This is the 20th special symposium devoted to the impact of high performance computing and communication on scientific computing and simulation. The symposium encompasses a wide variety of topics with a focus on tools and applications for the simulation of physical and engineering systems. The goal of the symposium is to encourage innovation and synergistic advances in these areas. It promotes the exchange of ideas and information between universities, industry, and national laboratories about new developments in system modeling, high performance computing and communication, and scientific computing and simulation. A particular focus this year is on adapting algorithms to work on some of the most current architectures. Fourteen high quality papers and two tutorial sessions will be presented in six technical sessions. The first tutorial is "Ingredients for good parallel performance on multicore systems" presented by Georg Hager of the University of Erlangen-Nurember. The second tutorial is on "Vienna CL", an open source linear algebra library that allows use of both GPUs and multicore CPUs, presented by Karl Rupp from the Vienna University of Technology. The Symposium features three keynote talks from highly regarded experts in the field. The first keynote talk is entitled "Designing multiple-fault tolerant RAIDS: Using graphs and hypergraphs". Prof. Narsingh Deo, Millican Chair and Director of the Center of Parallel Computation at the University of Central Florida. Abstract. Redundant Arrays of Independent Disks (RAID) systems are in widespread use because of their enhanced I/O bandwidths, large capacities, and low cost. However, the increasing demand for greater array capacities at low cost has led to the use of arrays with larger and larger number of disks, which increases the likelihood of the concurrent occurrence of two or more random disk failures. Hence the need for RAID systems to tolerate two or more random disk failures without compromising disk utilization. In this talk, we will present a novel algorithm based on the perfect 1-factorization of the complete graphs KP and K2P - 1 for placing data and parity in two-disk fault-tolerant arrays with (P - k) and (2P - 1 - k) disks respectively, where P is a prime number and k greater than or equatl to 1. Furthermore, we determine the fraction of space used for storing parity in such arrays and show that this fraction has the optimal value when k = 1. The second keynote talk is "Accelerating linear system solutions on new parallel architectures", presented by Prof. Marc Baboulin, Inria Excellence Research Chair at the University Paris-Sud. Abstract. Recent years have seen an increase in peak "local" speed through parallelism in terms of multicore processors and GPU accelerators. At the same time, the cost of communication between memory hierarchies and/or between processors have become a major bottleneck for most linear algebra algorithms. In this presentation we explain how hybrid multicore+GPU systems can be used efficiently to enhance performance of linear algebra libraries. We illustrate this approach by considering hybrid factorizations where we split the computation over a multicore and a graphic processor and where the amount of communication is significantly reduced. We also show how mixed precision algorithms can improve performance. Next we describe a randomized algorithm that accelerates factorization of general or symmetric indefinite systems on multicore or hybrid multicore+GPU systems. Randomization prevents the communication overhead due to pivoting, is computationally inexpensive, requires very little storage. The resulting solvers outperform existing routines while providing us with a satisfying accuracy. A third invited presentation is "Exascale algorithms for synthesizing parameters of computational models" by Prof. Sumit Kumar Jha of the University of Central Florida. Abstract: The success of high performance computing has facilitated the rapid development of increasingly complex models of natural and engineered systems by biologists, physicists, chemists, and even financial engineers. While the development of such models requires considerable domain knowledge and arguably little knowledge of the science of computing itself, we survey a key problem in computational modeling that cuts across boundaries of scientific disciplines and motivates the development of new massively parallel high performance algorithms: the synthesis of parameters for stochastic computational models. The overall structure of stochastic computational models can often be obtained from first principles by using our understanding and insight into the physical system that is being modeled. However, several components of a computational model are not readily obtained from first principles. Very often, model designers incorporate such information in the model as parameters. The model designer chooses these parameter values carefully so that the computational model replicates the behavior of the natural or engineered system being modeled. Naturally, a key problem in computational modeling is the identification of such parameters. While the insight of the domain knowledge expert was sufficient to estimate parameters of small stochastic models, there is an urgent need to develop massively parallel algorithmic techniques for synthesizing parameters of large and complex stochastic models. In this talk, we will survey massively parallel algorithms for synthesizing parameters of stochastic models from semi-quantiative and qualitative specifications. We will study the use of stochastic temporal logics for describing the expected behavior from complex stochastic models, and argue that domain-oriented flavors for temporal logics will facilitate the development of discipline-specific formal frameworks for specifying correctness of computational models. We look forward to hosting a very successful High Performance Computing Symposium this year. Gary Howell, General Chair North Carolina State University Fang(Cherry) Liu, General Vice-Chair Ames Laboratory Steven Seidel, Program Chair Michigan Technological University Rhonda Phillips, Program Vice-Chair MIT Lincoln Laboratory Karl Rupp, Publicity Chair Vienna University of Technology.