status and plans at kek shoji hashimoto workshop on lqcd software for blue gene/l, boston...

Status and plans at KEK

Shoji Hashimoto (KEK)@ Workshop on LQCD Software for

Blue Gene/L, Boston University, Jan. 27, 2006

Jan 27, 2006 Shoji Hashimoto (KEK) 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/LIBM Blue Gene/L 57 TFlop57 TFlopss


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.


Usage

Lattice QCD is a dominant user.• About 60-80% of the computer time f

or lattice QCD– Among them, ~60% has been used by t

he JLQCD collaboration– Others include Hatsuda-Sasaki, Nakam

ura et al., Suganuma et al., Suzuki et al., …

• Simulation for accelerator design is another big user: beam-beam simulation for the KEK B factory.


JLQCD collaboration

• 1995~ (on VPP500)– Continuum limit in the quenched

approximation

BK fB, fDms


JLQCD collaboration

• 2000~ (on SR8000)– Dynamical QCD with the improved Wils

on fermion

mV vs mPS2 fB, fBs Kl3 form factor


Around the triangle


The wall• Using the clover dyna

mical quark.• Chiral extrapolation h

as 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)


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.


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.


Installation

Dec. 26, 2005


Installation

Dec. 27, 2005

Jan. 11, 2006

Jan. 13, 2006


Jan. 25, 2006


Benchmark

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 o

n-chip L3• ~22% of the peak

performance


JLQCD physics target

Dynamical overlap fermion for light and heavy flavor physics:

• f, fK, BK, fB, etc.• control chiral extrapolation with mq do

wn to ms/4-ms/6.• Starting from Nf=2, then 2+1.• 163x32 and 243x48 (multiples of 8 onl

y!)• Feasible with our current (crude) time

estimate


Algorithm• Hybrid Monte Carlo with the “reflection/refr

acion”– Fodor, Kats, Szabo; Cundy et al.; DeGrand, Sch

aefer• 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.


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.

status and plans at kek shoji hashimoto workshop on lqcd software for blue gene/l, boston...

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