Status and plans at KEK Shoji Hashimoto Workshop on LQCD Software for Blue Gene/L, Boston...
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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
Jan 27, 2006 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.
Jan 27, 2006 Shoji Hashimoto (KEK) 4
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.
Jan 27, 2006 Shoji Hashimoto (KEK) 5
JLQCD collaboration
• 1995~ (on VPP500)– Continuum limit in the quenched
approximation
BK fB, fDms
Jan 27, 2006 Shoji Hashimoto (KEK) 6
JLQCD collaboration
• 2000~ (on SR8000)– Dynamical QCD with the improved Wils
on fermion
mV vs mPS2 fB, fBs Kl3 form factor
Jan 27, 2006 Shoji Hashimoto (KEK) 7
Around the triangle
Jan 27, 2006 Shoji Hashimoto (KEK) 8
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)
Jan 27, 2006 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.
Jan 27, 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.
Jan 27, 2006 Shoji Hashimoto (KEK) 11
Installation
Dec. 26, 2005
Jan 27, 2006 Shoji Hashimoto (KEK) 12
Installation
Dec. 27, 2005
Jan. 11, 2006
Jan. 13, 2006
Jan 27, 2006 Shoji Hashimoto (KEK) 13
Jan. 25, 2006
Jan 27, 2006 Shoji Hashimoto (KEK) 14
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
Jan 27, 2006 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 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
Jan 27, 2006 Shoji Hashimoto (KEK) 16
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.
Jan 27, 2006 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.