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Status and plans at KEK

Status and plans at KEK. Shoji Hashimoto (KEK) @ Workshop on LQCD Software for Blue Gene/L, Boston University, Jan. 27, 2006. KEK supercomputer. Leading computing facility in that time 1985 Hitachi S810/10 350 MFlops 1989 Hitachi S820/80 3 GFlops 1995 Fujitsu VPP500 128 GFlops

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Status and plans at KEK

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  1. Status and plans at KEK Shoji Hashimoto (KEK) @ Workshop on LQCD Software for Blue Gene/L, Boston University, Jan. 27, 2006

  2. KEK supercomputer Leading computing facility in that time • 1985 Hitachi S810/10 350 MFlops • 1989 Hitachi S820/80 3 GFlops • 1995 Fujitsu VPP500 128 GFlops • 2000 Hitachi SR8000 F1 1.2 TFlops • 2006 Hitachi SR11000 2.15 TFlops IBM Blue Gene/L 57 TFlops Shoji Hashimoto (KEK)

  3. Machine is for … • “KEK Large Scale Simulation Program” : call for proposals of project to be performed on the supercomputer. • Open for Japanese groups on particle and nuclear physics • Program Advisory Committee (PAC) decides the approval and machine time allocation. Shoji Hashimoto (KEK)

  4. Usage Lattice QCD is a dominant user. • About 60-80% of the computer time for lattice QCD • Among them, ~60% has been used by the JLQCD collaboration • Others include Hatsuda-Sasaki, Nakamura et al., Suganuma et al., Suzuki et al., … • Simulation for accelerator design is another big user: beam-beam simulation for the KEK B factory. Shoji Hashimoto (KEK)

  5. JLQCD collaboration • 1995~ (on VPP500) • Continuum limit in the quenched approximation ms BK fB, fD Shoji Hashimoto (KEK)

  6. JLQCD collaboration • 2000~ (on SR8000) • Dynamical QCD with the improved Wilson fermion mV vs mPS2 fB, fBs Kl3 form factor Shoji Hashimoto (KEK)

  7. Around the triangle Shoji Hashimoto (KEK)

  8. Using the clover dynamical quark. Chiral extrapolation has been very hard to go beyond ms/2 Maybe, solved by new formulations, algorithms and/or machines… JLQCD Nf=2 (2002) MILC coarse lattice (2004) The wall Shoji Hashimoto (KEK)

  9. Upgrade • Process started in 2004. • Called for bids from vendors. • At least 20x more computing power, measured mainly using the QCD codes. • No restriction on architecture (scalar or vector, etc.), but some amount must be a shared memory machine. • Decision was made in September, 2005. • Operation will start on March 1st, 2006. Shoji Hashimoto (KEK)

  10. The next machine A combination of two systems: • Hitachi SR11000 K1, 16 nodes, 2.15 TFlops peak performance. • POWER5 based, 16-way SMP • IBM Blue Gene/L, 10 racks, 57.3 TFlops peak performance. • 80TB RAID + tape library (~PB) Hitachi Ltd. is the prime contractor. Shoji Hashimoto (KEK)

  11. Installation Dec. 26, 2005 Shoji Hashimoto (KEK)

  12. Installation Dec. 27, 2005 Jan. 13, 2006 Jan. 11, 2006 Shoji Hashimoto (KEK)

  13. Shoji Hashimoto (KEK) Jan. 25, 2006

  14. Wilson solver 243x48 lattice on a midplace (8x8x8=512 nodes, half rack) 29.2% of the peak performance 32.6% if measured the Dslash only Domain-wall solver 243x48 lattice on a midplace; Ns=16. Doesn’t fit in the on-chip L3 ~22% of the peak performance Benchmark Shoji Hashimoto (KEK)

  15. JLQCD physics target Dynamical overlap fermion for light and heavy flavor physics: • f, fK, BK, fB, etc. • control chiral extrapolation with mq down to ms/4-ms/6. • Starting from Nf=2, then 2+1. • 163x32 and 243x48 (multiples of 8 only!) • Feasible with our current (crude) time estimate Shoji Hashimoto (KEK)

  16. Algorithm • Hybrid Monte Carlo with the “reflection/refracion” • Fodor, Kats, Szabo; Cundy et al.; DeGrand, Schaefer • Or, staying in a fixed topological sector • May choose a gauge action generating well-conditioned HW, e.g. Iwasaki, DBW2 • Numerically easier (can avoid O(V2) scaling); better locality • Topological charge doesn’t change frequently, anyway, as the continuum limit is approached. • Artifact is O(1/V); Q dependence is analytically known for some quantities: Brower et al. Shoji Hashimoto (KEK)

  17. Summary • New KEK machine will be made available for Japanese lattice community on March 1st, 2006. • Hitachi SR11000 (2.15 TF) + IBM BlueGene/L (57.3 TF) • JLQCD is going to start dynamical overlap simulations; basic codes are under development/tests. Testing algorithms. Optimization for BGL has to be done according to the Jun’s strategy. Shoji Hashimoto (KEK)

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