QCD Project Overview

Ying Zhang

September 26, 2005

DOE SciDAC Program

 Scientific Discovery through advanced Computing  Funded by Department of Energy, the Office of Science (SC) 

http://www.scidac.org/

 Goals:  Translate the computing technology advances in 21 st century into corresponding increases in the capabilities of scientific codes  Research, development and deployment of software to accelerate the development of scientific codes and to achieve maximum efficiency on high-end computers  Research on network technologies and software to link researchers and to facilitate movement of large data sets

DOE SciDAC Program

Source: SciDAC web site

DOE SciDAC Program

 Several programs under SciDAC  Under Advanced Scientific Computing (MICS)  High-End Computer System Performance: PERC  And others…  Under High Energy Nuclear Physics (HENP)   National Infrastructure for Lattice Gauge Computing (Lattice QCD) And others…  Several others on Biology, Fusion Energy, Basic Energy, …

SciDAC Lattice QCD

 Involves most U.S. lattice theorists    funding primarily for software, but also clusters integration of disparate activities software structure for code/data interoperability  Two, complementary hardware approaches   commodity clusters at FermiLab and Jefferson Lab QCDOC hardware at Columbia/Brookhaven  Software  QMP, communication library optimized for QCD • Myrinet GM, QCDOC mesh and MPI     QLA, lattice-aware single node linear algebra QDP, lattice wide data parallel computations QIO, parallel file I/O optimized inverters

Lattice QCD

 Quantum Chromodynamics (QCD)  strong interaction between quarks, mediated by gluons  Both nuclear physicists and high-energy physicists are involoved  PI: Bob Sugar at UCSB  Lattice QCD  numerical simulation of QCD via discretized space/time • quarks at lattice points, with gluons mediating along edges – SU(3) matrix operations dominate the calculation  yields complex, sparse matrices • solution via conjugate gradient techniques  MILC (MIMD Lattice Computation)  one lattice QCD implementation 

http://www.usqcd.org/

Lattice QCD

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 Source: Richard C. Brower & Robert Edwards  1 2

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Level 3

Lattice QCD Software Plans

Optimized Dirac Operators, Inverters

Optimized for Pentium 4 and QCDOC

Level 2 QDP (QCD Data Parallel) Lattice Wide Operations, Data shifts QIO XML I/O DIME QLA (QCD Linear Algebra) Level 1 QMP (QCD Message Passing)

C/C++ implementation

Source: Richard C. Brower & Robert Edwards

C/C++ implementation supports MPI, GM, QCDOC and gigabit Ethernet

Current Work

 Application benchmarking    MILC and Chroma(C++) codes Opteron, Intel, Power, SGI, BG/L, QCDOC, Cray, … 10-100/GigE/10-GigE Ethernet, Quadrics, Myrinet, Infiniband  Bottleneck and scalability analysis  processor count, cache size, and lattice size  Total cost of ownership  power-performance products and scaling  Multiversion code selection  CG configuration and tuning  Performance optimization  Performance profiling library development