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Idomura, Yasuhiro; Ina, Takuya*; Ali, Y.*; Imamura, Toshiyuki*
Dai-34-Kai Suchi Ryutai Rikigaku Shimpojiumu Koen Rombunshu (Internet), 6 Pages, 2020/12
A new communication avoiding (CA) Krylov solver with a FP16 (half precision) preconditioner is developed for a semi-implicit finite difference solver in the Gyrokinetic Toroidal 5D full-f Eulerian code GT5D. In the solver, the bottleneck of global collective communication is resolved using a CA-Krylov subspace method, and halo data communication is reduced by the FP16 preconditioner, which improves the convergence property. The FP16 preconditioner is designed based on the physics properties of the operator and is implemented using the new support for FP16 SIMD operations on A64FX. The solver is ported also on GPUs, and the performance of ITER size simulations with 
trillion grids is measured on Fugaku (A64FX) and Summit (V100). The new solver accelerates GT5D by 
from the conventional non-CA solver, and excellent strong scaling is obtained up to 5,760 CPUs/GPUs both on Fugaku and Summit.
Idomura, Yasuhiro; Ina, Takuya*; Ali, Y.*; Imamura, Toshiyuki*
Proceedings of Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo 2020 (SNA + MC 2020), p.225 - 230, 2020/10
A new communication avoiding (CA) Krylov solver with a FP16 (half precision) preconditioner is developed for a semi-implicit finite difference solver in the Gyrokinetic Toroidal 5D full-f Eulerian code GT5D. In the solver, the bottleneck of global collective communication is resolved using a CA-Krylov subspace method, while the number of halo data communication is reduced by improving the convergence property using the FP16 preconditioner. The FP16 preconditioner is designed based on the physics properties of the operator and is implemented using the new support for FP16 SIMD operations on A64FX. The solver is ported on Fugaku (A64FX) and Summit (V100), which respectively show 
63x and 29x speedups in socket performance compared to the conventional non-CA Krylov solver on JAEA-ICEX (Haswell).
Idomura, Yasuhiro; Ina, Takuya*; Mayumi, Akie; Yamada, Susumu; Imamura, Toshiyuki*
Lecture Notes in Computer Science 10776, p.257 - 273, 2018/00
Times Cited Count：2 Percentile：50.01(Computer Science, Artificial Intelligence)A preconditioned Chebyshev basis communication-avoiding conjugate gradient method (P-CBCG) is applied to the pressure Poisson equation in a multiphase thermal-hydraulic CFD code JUPITER, and its computational performance and convergence properties are compared against a preconditioned conjugate gradient (P-CG) method and a preconditioned communication-avoiding conjugate gradient (P-CACG) method on the Oakforest-PACS, which consists of 8,208 KNLs. The P-CBCG method reduces the number of collective communications with keeping the robustness of convergence properties. Compared with the P-CACG method, an order of magnitude larger communication-avoiding steps are enabled by the improved robustness. It is shown that the P-CBCG method is 
and 
faster than the P-CG and P-CACG methods at 2,000 processors, respectively.
Yamada, Susumu; Imamura, Toshiyuki*; Machida, Masahiko; Arakawa, Chuichi*
Nihon Keisan Kogakkai Rombunshu, 7, p.243 - 252, 2005/05
no abstracts in English
Laird, J. S.; Hirao, Toshio; Onoda, Shinobu; Wakasa, Takeshi; Yamakawa, Takeshi; Abe, Hiroshi; Oyama, Hidenori*; Kamiya, Tomihiro
JAERI-Review 2004-025, TIARA Annual Report 2003, p.14 - 16, 2004/11
no abstracts in English
Maesako, Hiroshi*; Suzuki, Yoshio; Aoyagi, Tetsuo; Nakajima, Norihiro
Fujitsu, 55(2), p.109 - 115, 2004/03
ITBL (Information Technology Based Laboratory) project is promoted under the "e-Japan national priority program" by six research institutions. The project aims to construct a virtual laboratory which aid collaborative studies amongst researchers by allowing for sharing of intellectual properties and resources such as supercomputer hardware, software, data, etc. In order to realize this virtual laboratory environment, the Japan Atomic Energy Research Institute is developing an ITBL system infrastructure software system. Some of the highlighted functions offered by the ITBL infrastructure are: authentication for connecting to the supercomputers, parallel and distributed communication, job execution on the connected supercomputers, and formation of communities for aiding communication amongst researchers. In this passage, besides the introduction of the ITBL infrastructure, a brief introduction of the Quantum Bioinformatics and the Numerical Environmental Systems will be given as examples of the applications developed on the ITBL infrastructure.
Shinozaki, Shinichi; Moriyama, Shinichi; Shimono, Mitsugu; Hiranai, Shinichi
NIFS-MEMO-36, p.87 - 90, 2002/06
no abstracts in English
Uehara, Hitoshi; Tamura, Masanori; Yokokawa, Mitsuo
Hai Pafomansu Komputingu To Keisan Kagaku Shimpojium (HPCS2002) Rombunshu, p.73 - 80, 2002/01
The Earth Simulator is an ultra high-speed supercomputer which is developed now for global environment change simulations. For achieving high performance computing on large scale distributed memory parallel computer such as the Earth Simulator, an optimization of communication processings in user applications is required, and the optimization needs an evaluation for performances of communication methods. In the Earth Simulator, Message Passing Interface (MPI) is supported as the communication method. We evaluated performances of the MPI-1/MPI-2 functions on the Earth Simulator in detail using MBL which we developed.
Muramatsu, Kazuhiro; Imamura, Toshiyuki; Kitabata, Hideyuki; Kaneko, Isamu; Takemiya, Hiroshi*; Hasegawa, Yukihiro*; Yamagishi, Nobuhiro*; Hirayama, Toshio
Keisan Kogaku Koenkai Rombunshu, 6(1), p.241 - 244, 2001/05
no abstracts in English
Imamura, Toshiyuki
GMD Report 132, 1 Pages, 2001/04
no abstracts in English
Onishi, Ryoichi*; Guo, Z.*; Imamura, Toshiyuki; Hirayama, Toshio
GMD Report 132, 1 Pages, 2001/04
no abstracts in English
Imamura, Toshiyuki; Muramatsu, Kazuhiro; Kitabata, Hideyuki*; Kaneko, Isamu*; Yamagishi, Nobuhiro*; Hasegawa, Yukihiro*; Takemiya, Hiroshi*; Hirayama, Toshio
Joho Shori Gakkai Kenkyu Hokoku 2001-ARC-142, p.49 - 54, 2001/03
no abstracts in English
Toyama, Shigeyuki*; Wakamatsu, Hisanori; Okazaki, Hikoya
JNC TJ7440 2000-019, 17 Pages, 2000/03
JNC-TJ7440-2000-019.pdf:1.95MB
no abstracts in English
Takemiya, Hiroshi*; Yamagishi, Nobuhiro*
JAERI-Data/Code 2000-006, p.172 - 0, 2000/02
JAERI-Data-Code-2000-006.pdf:5.37MB
no abstracts in English
Imamura, Toshiyuki; Tokuda, Shinji
Proceedings of IASTED International Conference on Parallel and Distributed Computing and Systems, p.583 - 588, 1999/00
no abstracts in English
Imamura, Toshiyuki; ; Takemiya, Hiroshi*
JAERI-Data/Code 98-034, 28 Pages, 1998/11
JAERI-Data-Code-98-034.pdf:1.32MB
no abstracts in English
Ebisawa, Katsumi; Shibata, Katsuyuki
SEISMO, 2(8), p.2 - 3, 1998/08
no abstracts in English
*
JAERI-Data/Code 98-020, 45 Pages, 1998/06
JAERI-Data-Code-98-020.pdf:1.5MB
no abstracts in English
; Imamura, Toshiyuki; *; *; Takemiya, Hiroshi*; Higuchi, Kenji; Kasahara, Hironori*;
Keisan Kogaku Koenkai Rombunshu, 3(1), p.81 - 84, 1998/05
no abstracts in English
Kawamata, Yoichi; *; Kurihara, Kenichi
Gijutsu Kenkyukai Hokoku (Mombusho Kokuritsu Temmondai, Denki Tsushin Daigaku), p.7 - 10, 1997/03
no abstracts in English
