01/21/2004 CS267-Lecture 1 1CS267/E233Applications of Parallel ComputersLecture 1: IntroductionKathy [email protected]://inst.eecs.berkeley.edu/~cs26708/27/2002 CS267-Lecture 1 2Outline• Introduction• Large important problems require powerful computers • Why powerful computers must be parallel processors • Principles of parallel computing performance• Structure of the course01/21/2004 CS267-Lecture 1 3Why we need powerful computers08/27/2002 CS267-Lecture 1 4Simulation: The Third Pillar of Science • Traditional scientific and engineering paradigm:1) Do theory or paper design.2) Perform experiments or build system.• Limitations:- Too difficult -- build large wind tunnels.- Too expensive -- build a throw-away passenger jet.- Too slow -- wait for climate or galactic evolution.- Too dangerous -- weapons, drug design, climate experimentation.• Computational science paradigm:3) Use high performance computer systems to simulate the phenomenon- Base on known physical laws and efficient numerical methods.08/27/2002 CS267-Lecture 1 5Some Particularly Challenging Computations• Science- Global climate modeling- Astrophysical modeling- Biology: genomics; protein folding; drug design- Computational Chemistry- Computational Material Sciences and Nanosciences• Engineering- Crash simulation- Semiconductor design- Earthquake and structural modeling- Computation fluid dynamics (airplane design)- Combustion (engine design)• Business- Financial and economic modeling- Transaction processing, web services and search engines• Defense- Nuclear weapons -- test by simulations- Cryptography08/27/2002 CS267-Lecture 1 6Units of Measure in HPC• High Performance Computing (HPC) units are:- Flops: floating point operations- Flop/s: floating point operations per second- Bytes: size of data (a double precision floating point number is 8)• Typical sizes are millions, billions, trillions…Mega Mflop/s = 106flop/sec Mbyte = 106byte(also 220= 1048576)Giga Gflop/s = 109flop/sec Gbyte = 109byte (also 230= 1073741824)Tera Tflop/s = 1012flop/sec Tbyte = 1012byte (also 240= 10995211627776)Peta Pflop/s = 1015flop/sec Pbyte = 1015byte (also 250= 1125899906842624)Exa Eflop/s = 1018flop/sec Ebyte = 1018byte08/27/2002 CS267-Lecture 1 7Economic Impact of HPC• Airlines:- System-wide logistics optimization systems on parallel systems.- Savings: approx. $100 million per airline per year.• Automotive design:- Major automotive companies use large systems (500+ CPUs) for:- CAD-CAM, crash testing, structural integrity and aerodynamics.- One company has 500+ CPU parallel system.- Savings: approx. $1 billion per company per year.• Semiconductor industry:- Semiconductor firms use large systems (500+ CPUs) for- device electronics simulation and logic validation - Savings: approx. $1 billion per company per year.• Securities industry:- Savings: approx. $15 billion per year for U.S. home mortgages.08/27/2002 CS267-Lecture 1 8Global Climate Modeling Problem• Problem is to compute:f(latitude, longitude, elevation, time) !temperature, pressure, humidity, wind velocity• Approach:- Discretize the domain, e.g., a measurement point every 10 km- Devise an algorithm to predict weather at time t+1 given t• Uses:- Predict major events, e.g., El Nino- Use in setting air emissions standardsSource: http://www.epm.ornl.gov/chammp/chammp.html08/27/2002 CS267-Lecture 1 9Global Climate Modeling Computation• One piece is modeling the fluid flow in the atmosphere- Solve Navier-Stokes problem- Roughly 100 Flops per grid point with 1 minute timestep• Computational requirements:- To match real-time, need 5x 1011flops in 60 seconds = 8 Gflop/s- Weather prediction (7 days in 24 hours) ! 56 Gflop/s- Climate prediction (50 years in 30 days) ! 4.8 Tflop/s- To use in policy negotiations (50 years in 12 hours) ! 288 Tflop/s• To double the grid resolution, computation is at least 8x • State of the art models require integration of atmosphere, ocean, sea-ice, land models, plus possibly carbon cycle, geochemistry and more• Current models are coarser than thisHigh Resolution Climate Modeling on NERSC-3 – P. Duffy, et al., LLNL08/27/2002 CS267-Lecture 1 11A 1000 Year Climate Simulation• Warren Washington and Jerry Meehl, National Center for Atmospheric Research; Bert Semtner, Naval Postgraduate School; John Weatherly, U.S. Army Cold Regions Research and Engineering Lab Laboratory et al.• http://www.nersc.gov/aboutnersc/pubs/bigsplash.pdf• Demonstration of the Community Climate Model (CCSM2)• A 1000-year simulation shows long-term, stable representation of the earth’s climate. • 760,000 processor hours used• Temperature change shown08/27/2002 CS267-Lecture 1 12Climate Modeling on the Earth Simulator System" Development of ES started in 1997 in order to make a comprehensive understanding of global environmental changes such as global warming." 26.58Tflops was obtained by a global atmospheric circulation code." 35.86Tflops (87.5% of the peak performance) is achieved in the Linpack benchmark." Its construction was completed at the end of February, 2002 and the practical operation started from March 1, 200208/27/2002 CS267-Lecture 1 13Astrophysics: Binary Black Hole Dynamics• Massive supernova cores collapse to black holes. • At black hole center spacetime breaks down. • Critical test of theories of gravity –General Relativity to Quantum Gravity. • Indirect observation – most galaxieshave a black hole at their center.• Gravity waves show black hole directly including detailed parameters.• Binary black holes most powerful sources of gravity waves. • Simulation extraordinarily complex –evolution disrupts the spacetime !08/27/2002 CS267-Lecture 1 1408/27/2002 CS267-Lecture 1 15Heart Simulation• Problem is to compute blood flow in the heart• Approach:- Modeled as an elastic structure in an incompressible fluid.- The “immersed boundary method” due to Peskin and McQueen.- 20 years of development in model- Many applications other than the heart: blood clotting, inner ear, paper making, embryo growth, and others- Use a regularly spaced mesh (set of points) for evaluating the fluid•Uses- Current model can be used to design artificial heart valves- Can help in understand effects of disease (leaky valves)- Related projects look at the behavior of the heart during a heart attack- Ultimately: real-time clinical work08/27/2002 CS267-Lecture 1 16Heart Simulation CalculationThe
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