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Workflows

Workflows. A Blind Alley in Grid Computing? Søren-Aksel Sørensen Department of Computer Science UCL. Data. Program. Job Control. Timeshare. Sixties work cycle. Timeshare. Seventies work cycle. Graphics. Hardcopy. Timeshare. Eighties/Nineties work cycle. Resource Network.

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Workflows

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  1. Workflows A Blind Alley in Grid Computing? Søren-Aksel Sørensen Department of Computer Science UCL

  2. Data Program Job Control Timeshare Sixties work cycle

  3. Timeshare Seventies work cycle Graphics Hardcopy

  4. Timeshare Eighties/Nineties work cycle

  5. Resource Network GRID work cycle

  6. Resource Network GRID work cycle That is not Progress! HPC evolution since 1960 • Timeshared batch environment retained • Job Control cards replaced by Work Flows • “Grid designers estimate that the average gridjob will take anywhere from daysto weeks” www.ppdg.net/ mtgs/18jun02-lbl/ppdg-idat-ucb-interactivity.ppt

  7. eScience • eScience is not financially viable. • Must rely on Commodities Off The Shelf (CESDIS 1993). • eScience must follow eBusiness • Workflow/Batch model unacceptable for eBusiness • Even RPC unsuitable. • Alternatives must be found if Grid computing is to survive.

  8. Science requires hands-on experience This is what I want

  9. Requirements • Steering capability • Rendering resources & devices • Haptic devices • Real time modeling • Resource prioritization • Network QoS • Dynamic resource control • How close are we to this?

  10. JANET Workstation Batch Data My setup 1994 Time Share

  11. JANET Workstation Workstation Data My setup 1995 PVM (1989)

  12. JANET Workstation Workstation Workstation Workstation Workstation Workstation Workstation Workstation Workstation Hub My setup 1997

  13. Server Server Gb switch Workstation JANET Switch Switch Switch Switch Switch Switch My setup 2004

  14. Server Server Gb switch Workstation JANET Switch Switch Switch Switch Switch Switch My setup 2005 Processing on Demand?

  15. Example: Particle interaction ~5,000 particles falling onto a surface. 18 processors are used in this example. Processors are colour coded. Observe colour changes as objects change their home. Sørensen 2004

  16. But there are problems • Because we are using human interaction, smooth progression is essential. • We immediately recognise the problem of load balancing. • But each model iteration does not require the same effort. • And don’t forget model induced variations in time increments (t). • We therefore need a dynamic resource supply.

  17. Load balance Distributing the load among the available processors is relatively easy. The model uses 90 herders on 18 processors so there is scope for herder migration to compensate for object migration.

  18. Time progression As collisions become dominant, time progression slows down. Transition is gradual because of particle size variations.

  19. User progression Resource management Load balancing is not sufficient. We need to manage the progression gradient throughout to compensate for changes in time step. This requires dynamic resource management

  20. Virtual Relocateable Execution Controller • Creates an interface between the application and a virtual machine. • Virtual machine interacts with schedulers and resource discovery services. • Responsible for: • information sharing. • fault recovery. • resource management. • migration policy. • Based on PVM+SSH

  21. Domain 0 GriDM Discovery Scheduling Requests Permits VREC JPortal Authentication Task generation Task submission Application Resource Holders GriDM GriDM GriDM GriDM SGE SGE SGE SGE Domain 1 Domain 2 Domain 3 Domain 4 JYDE Application

  22. Ready for questions

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