第9回ASE研究会のお知らせ

日時：2011年2月17日（木）14時00分～17時30分
場所：東京大学　情報基盤センター　3階　大会議室（情報基盤センター案内地図）
主催：東京大学情報基盤センター　スーパーコンピューティング部門

【招待講演】

14：00 - 15：00

Speaker

　Dr. Osni Marques（Lawrence Berkeley National Laboratory）

Title

　Extreme Levels of Computing: Challenges and Opportunities

Abstract

　Exascale computing capabilities are expected to become a reality by the end of this decade. The pursuit of these capabilities is greatly motivated by the needs of a range of applications: exascale offers an unprecedented opportunity for transformative discovery, prediction and design.
Nonetheless, the path to such levels of computing presents formidable technological challenges. Expected changes in hardware will impact the way exascale computers are not only programmed but also built. Meanwhile, it is necessary to have a strategy to make the transition from current to extreme levels of computing less painful to the broad scientific computing community. In this presentation we will give an overview of efforts, in particular those under the auspices of the US Department of Energy, which aim at extreme levels of computing.

【講演】

15時15分～16時15分

Speaker

　Kengo Nakajima（Information Technology Center The University of Tokyo）

Title

　Effect of coarse grid solver of parallel multigird preconditioning for Krylov iterative method on multi-core cluster with 8,192 cores

Abstract

　Strategy of relaxation in coarse grid level of multigrid solver strongly affects the convergence of entire solver.
In this talk, recent experiences on this issue using "T2K Open Supercomputer (Tokyo)"
and "Cray-XT4" at Lawrence Berkeley National Laboratory with up to 8,192 cores will be presented.
Both of flat-MPI and Open/MPI hybrid parallel programming models are implemented.
Results show that effect of coarse grid solver is significant when number of MPI processes is more than order of 10³.

16時30分～17時30分

Speaker

　Takahiro Katagiri（Information Technology Center The University of Tokyo）

Title

　Xabclib2011 : A Sparse Iterative Solver with an Auto-tuning Facility
　--- New AT Functions Developed in 2011 ---

Abstract

　We have developed a sparse iterative solver with an auto-tuning (AT) facility, named Xabclib. In this presentation, we will present newly developed functions for the AT. The release version including the new AT functions is called Xabclib2011.
　
　The main functions for AT in Xabclib2011 are follows:

　In the first AT function, we have developed codes from scratch to establish thread-safety in Xabclib2011. This enables us to establish hybrid MPI programming for the library.

　In the second AT function, we have developed new implementations for linear algebra algorithms. The first algorithm is based on the BiCG-Stab algorithm for linear equations solver. This establishes stability of convergence to conventional preconditioning implementation. The second algorithm is based on the Arnoldi algorithm with explicit restart for eigensolvers. This establishes an efficient restating with real vectors, although its solution vectors are complex in general.

　In the third AT function, we have developed a new implementation for sparse matrix vector multiplications (SpMV) with segmented scan (SS) method for scalar processors. This establishes dynamic parameter change for SS on SpMV.

　We will show preliminary results of performance evaluation with Xacblib2011 by using one node of the T2K Open supercomputer, which is the AMD quad-core Opteron with 16 cores.

18時00分～

　懇親会（根津周辺）

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懇親会参加票（katagiri＠cc.u-tokyo.ac.jpまで）

日時：2011年2月17日（木）
　　　18時00分～
場所：根津周辺
会費：4000円程度

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〒113-8658　東京都文京区弥生2－11－16
東京大学　情報基盤センター

ASE研究会幹事　特任准教授　片桐孝洋
E-mail：katagiri＠cc.u-tokyo.ac.jp
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