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NASA High Performance Computing (HPC) Directions, Issues, and Concerns: A User’s Perspective

This presentation by Dr. Robert C. Singleterry Jr. at the NASA HPC Users Forum highlights key issues, directions, and concerns regarding high-performance computing (HPC) at NASA. It discusses current computational resources, trends in scaling core counts, and challenges related to job queuing and algorithm scalability. The case study on space radiation explores how HPC has influenced spacecraft design and research outcomes. Central to the discussion is the balancing act between advancing hardware and optimizing algorithms to meet future computing demands.

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NASA High Performance Computing (HPC) Directions, Issues, and Concerns: A User’s Perspective

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  1. NASA High Performance Computing (HPC) Directions, Issues, and Concerns:A User’s Perspective Dr. Robert C. Singleterry Jr. NASA Langley Research Center HPC Users Forum at HRLS and EPFL Oct 5 & 8, 2009

  2. Overview • Current Computational Resources • Directions from My Perspective • My Issues and Concerns • Conclusion? • Case Study – Space Radiation • Summary HPC Users Forum

  3. Current Computational Resources • Ames • 51,200 cores (Pleiades) • 1GB/core • LUSTRE • Langley • 3000+ cores (K) • 1GB/core • LUSTRE • Goddard • 4000+ Nehalem (new Discover) cores • 3GB/core • GPFS • Others at other centers HPC Users Forum

  4. Current Computational Resources • Science applications • Star and galaxy formation • Weather and climate modeling • Engineering applications • CFD • Ares-I and Ares-V • Aircraft • Orion reentry • Space radiation • Structures • Materials • Satellite operations, data analysis & storage HPC Users Forum

  5. Directions from My Perspective • 2004: Columbia • 10,240 cores • 2008: Pleiades • 51,200 cores • 2012 System • 256,000 cores • 2016 System • 1,280,000 cores • Extrapolation • Use at own risk 5 times more cores every 4 years HPC Users Forum

  6. My Issues and Concerns • Assume power and cooling are not issues • Is this a valid assumption? • What will a “core” be in the next 7 years? • “Nehalem”-like – powerful, fast, and “few” • “BlueGene”-like – minimal, slow, and “many” • “Cell”-like – not like CPU at all, fast, and many • “Unknown”-like – combination, hybrid, new, … • In 2016, NASA should have a 1.28 million core machine tightly coupled together • Everything seems to be fine Maybe??? HPC Users Forum

  7. Issues and Concerns? • A few details about our systems • Each of the 4 NASA Mission Directorates “own” part of Pleiades, Columbia, and Schirra • Each Center and Branch resource control their own machines in the manner they see fit • Queues limit the number of cores used per job per Directorate, Center, or Branch • Queues limit the time per job without special permissions from the Directorate, Center, or Branch • This harkens of a time share machine of old HPC Users Forum

  8. Issues and Concerns? • As machines get bigger, 1.28 million cores in 2016, do the queues get bigger? • Can the NASA research, engineer, and operation users utilize the bigger queues? • Will NASA algorithms keep up with the 5 times scaling every 4 years? • 2008: 2000 core algorithms • 2016: 50,000 core algorithms • Are we spending money on the right issue? • Newer, bigger, better hardware • Newer, better, scalable algorithms HPC Users Forum

  9. Conclusions? • Do I have a conclusion? • I have issues and concerns! • Spend money on bigger and better hardware? • Spend money on more scalable algorithms? • Do the NASA funders understand these issues from a researcher, engineer, and operations point of view? • Do I as a researcher and engineer understand the NASA funder point of view? • At this point, I do not have a conclusion! HPC Users Forum

  10. Case Study – Space Radiation • Cosmic Rays and Solar Particle Events • Nuclear interactions • Human and electronic damage • Dose Equivalent: damage caused by energy deposited along the particle’s track HPC Users Forum

  11. Previous Space Radiation Algorithm • Design and start to build spacecraft • Mass limits and objectives have been reached • Brought in radiation experts • Analyzed spacecraft by hand (not parallel) • Extra shielding needed for certain areas of the spacecraft or extra component capacity • Reduced new mass to mass limits by lowering the objectives of the mission • Throwing off science experiments • Reducing mission capability HPC Users Forum

  12. Previous Space Radiation Algorithm • Major missions impacted in this manner • Viking • Gemini • Apollo • Mariner • Voyager HPC Users Forum

  13. Previous Space Radiation Algorithm SAGE III HPC Users Forum

  14. Primary Space Radiation Algorithm • Ray trace of spacecraft/human geometry • Reduction of ray trace materials to three ordered materials • Aluminum • Polyethylene • Tissue • Transport database • Interpolate each ray • Integrate each point • Do for all points in the body - weighted sum HPC Users Forum

  15. Primary Space Radiation Algorithm • Transport database creation is mostly serial and not parallelizable in coarse grain • 1,000 point interpolation over database is parallel in the coarse grain • Integration of data at points is parallel if we buy the right library routines • At most, a hundreds-of-core process over hours of computer time • Not a good fit for the design cycle • Not a good fit for the HPC of 2012 and 2016 HPC Users Forum

  16. Imminent Space Radiation Algorithm • Ray trace of spacecraft/human geometry • Run transport algorithm along each ray • No approximation on materials • Integrate all rays • Do for all points • Weighted sum HPC Users Forum

  17. Imminent Space Radiation Algorithm • 1,000 rays per point • 1,000 points per body • 1,000,000 transport runs @ 1 sec to 3 mins per ray and point (depends on BC) • Integration of data at points is bottleneck • Data movement speed is key • Data size is small • This process is inherently parallel if communication bottleneck is reasonable • Better fit for HPC of 2012 and 2016 HPC Users Forum

  18. Future Space Radiation Algorithms • Monte Carlo methods • Data communications is bottleneck • Each history is independent of other histories • Forward/Adjoint finite element methods • Same problems as other finite element codes • Phase space decomposition is key • Hybrid methods • Finite Element and Monte Carlo together • Best of both worlds (on paper anyway) • Variational methods • Unknown at this time HPC Users Forum

  19. Summary • Present space radiation methods are not HPC friendly or scalable • Why do we care? Are algorithms good enough? • Need scalability to • Keep up with design cycle • Slower speeds of the many core chips • New bells & whistles wanted by funders • Imminent method better but has problems • Future methods show HPC scalability promise on paper but need resources for investigation and implementation HPC Users Forum

  20. Summary • NASA is committed to HPC for science, engineering, and operations • Issues & concerns about where resources are spent & how they impact NASA’s work • Will machines be bought that can benefit science, engineering, and operations? • Will resources be spent on algorithms that can utilize the machines bought? • HPC help desk created to inform and work with users to achieve better results for NASA work: HeCTOR Model HPC Users Forum

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