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Greenbook/OASCR Activities

Greenbook/OASCR Activities. Focus on technology to enable SCIENCE to be conducted, i.e. Software tools Software libraries Mike Minkoff/ANL. Outline . MPI Extensions and Programming Models Grid-based computing -- MPICH-G2 Grid-based Climate Simulation.

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Greenbook/OASCR Activities

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  1. Greenbook/OASCR Activities Focus on technology toenableSCIENCEto be conducted, i.e. Software tools Software libraries Mike Minkoff/ANL Greenbook 2001/OASCR

  2. Outline • MPI Extensions and Programming Models • Grid-based computing -- MPICH-G2 • Grid-based Climate Simulation Greenbook 2001/OASCR

  3. Standards-Based Programming Environments • MPI (Message-Passing Interface) standard defines a portable library interface for the message-passing model of parallel computation. • MPICH is a portable, high-performance implementation of the Standard. • Many vendor implementations of MPI have been based on MPICH. • Research continues on implementation issues, necessary for increased performance and scalability. Greenbook 2001/OASCR

  4. Beyond Message-Passing • MPI-2 is an standard extension to the message-passing model specification, with • Parallel I/O • Dynamic creation of processes • One-sided remote memory access • MPICH will soon provide a portable implementation of MPI-2. Greenbook 2001/OASCR

  5. Experimental Programming Models • Robust implementations of language extensions, such as co-array Fortran, are needed if such approaches are to evolve into real productivity enhancers for DOE applications. • More speculatively, new memory-centric programming and execution models will be needed for future machine architectures. • Argonne is leading an effort to explore both near-term and longer-term programming model issues. Greenbook 2001/OASCR

  6. MPICH-G2 • Developed by Karonis (NIU) and Toonen (ANL) • Based on ANL’s MPICH library (Gropp & Lusk) • A grid-enabled MPI • http://www.niu.edu/mpi Greenbook 2001/OASCR

  7. MPICH-G2: A grid-enabled MPI • Uses many Globus services • job startup • GSI for security • data conversion • asynchronous socket communication (Globus I/O) • Multi-protocol support • vendor-supplied MPI for intra-machine messages • TCP for inter-machine messages Greenbook 2001/OASCR

  8. MPI “grid” Applications • MPI applications wanting to solve problems too big for any single computer • Use MPICH-G2 to couple multiple computers forming a computational grid • Modify application to respect slower LAN/WAN performance Greenbook 2001/OASCR

  9. Cactus • Developed at Max Planck Institute for Gravitational Physics, Germany • Originally developed as framework for the numerical solution to Einstein’s Equations • Evolved into general-purpose problem solving environment that provides a modular and parallel computational framework atop MPI Greenbook 2001/OASCR

  10. Cactus-G: A Case Study • Cactus-G: coupled Cactus and MPICH-G2 • Multiple machines • T3E 900, IBM SP2 - NERSC • Origin O2K, IBM SP - ANL • Origin O2K - NCSA • IBM SP - SDSC Greenbook 2001/OASCR

  11. Our Experience • Primary problem: WAN performance between sites far below what was “advertised” • Machines with single portal (processor/network interface) to the WAN contributed to WAN performance problem • Our conclusions: • Don’t need a bigger machine • Need better communication performance between existing machines • Machine architecture need to supports high-bandwidth, multi-stream, off-machine communication Greenbook 2001/OASCR

  12. Next Generation NERSC - Grid Computing • Grid access using Globus to enable • remote job submission to all NERSC computer systems • data transfer to/from NERSC computers using GRID technologies, including tape storage • develop a new generation of GRID enabled tools to facilitate job submission, monitoring and analysis Greenbook 2001/OASCR

  13. Next Generation NERSC - Climate Computing • Integrating climate models requires • multi-teraflop scale computer systems able to deliver teraflop performance to a single user on a routine basis • ability to perform long duration simulations which requires access to a large number of processors and TB of disk space • enhanced software tools for analysis & visualization of TB of model results Greenbook 2001/OASCR

  14. Science Projects • Three-dimensional premixed turbulent flames with full chemistry model (J. Bell, LBNL) • Discrete Event Simulation (M. Novotny, FSU) Greenbook 2001/OASCR

  15. Remote and secure job submission and storage access. Support for PSEs Role of Nanotech/SCIDAC simulation reqs. Diversity vs. single-source machine Role of Libraries (IMSL, EISPACK) that are dated and/or single processor Role of NERSC Math Server Integrated debugging/performance tool Extend UHU to OASCR/App. matching Questions to PonderWhat Should NERSC Support Spend Resources On? Greenbook 2001/OASCR

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