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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:
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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 21st 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 Source: Richard C. Brower & Robert Edwards
Optimized for Pentium 4 and QCDOC Optimized Dirac Operators, Inverters Level 3 QIO QDP (QCD Data Parallel) XML I/O DIME Level 2 Lattice Wide Operations, Data shifts C/C++ implementation QLA (QCD Linear Algebra) Level 1 QMP (QCD Message Passing) C/C++ implementation supports MPI, GM, QCDOC and gigabit Ethernet Lattice QCD Software Plans Source: Richard C. Brower & Robert Edwards
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