Computer Science Department 1 Load Balancing and Grid Computing David Finkel Computer Science Department Worcester Polytechnic Institute

Computer Science Department 2 References “The Anatomy of the Grid”, Ian Foster, Carl Kesselman, Steven Tuccke, International Journal of Supercomputer Applications, 2001 “A Performance Oriented Migration Framework for the Grid”, Satish S. Vadhiyar and Jack J. Dongarra, Proceedings of CCGrid 2003, Third IEEE/ACM International Symposium on Cluster Computing and the Grid Innumerable papers by PEDS members Finkel, Wills and Finkel, and Claypool and Finkel, with additional co- authors.

Computer Science Department 3 What is the Grid? (Foster et al paper) Distributed computing infrastructure for advanced science and engineering Runs over the Internet, potentially world- wide Several approaches have emerged: Paper discusses Globus Toolkit

Computer Science Department 4 The Grid Concept Coordinated resource sharing and problem solving in dynamic, multi-institutional virtual organizations. Highly controlled, with resource providers and consumers defining what is shared and the conditions of sharing. Issues to address: Protocols, privacy, security, costs, …

Computer Science Department 5 Related approaches Application Service Providers Storage Service Providers CORBA DCE Volunteer Computing home, Distriblets, SLINC)

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7 Fabric Layer Provides access and control to resources Resources: Computational, storage, network Enquiry functions: to determine characteristics and state of a resource Management functions: Start, stop computations, reserve bandwidth

Computer Science Department 8 Collective Layer Protocols and services not associated with a particular resource –Directory services for discovery of resources –Co-allocation, scheduling, brokering –Monitoring the Virtual Organization for failure, intrusion detection, etc.

Computer Science Department 9 Load Sharing - Overview Transferring work from a heavily loaded node to a lightly loaded node Purpose: To improve application performance Transferring processes not suitable for fine- grain parallelism Also known as: Load Balancing, Process Migration.

Computer Science Department 10 Load Sharing Issues Criteria for heavily-loaded, lightly loaded Measuring load (policy, implementation) Exchanging information about load, state Which jobs to transfer When to transfer (new processes only, already-running processes)

Computer Science Department 11 Load Sharing in the Grid “A Performance Oriented Migration Framework for the Grid”, Vadhiyar and Donngarra Part of the GrADS project – Grid Application Development System – based at Univ. of Tennessee and other institutions Designed for long-running computations

Computer Science Department 12 Load Sharing in the Grid - 2 Basic idea – the load sharing system can run a performance model of a computation to estimate running time and resource requirements. Application programmer is responsible for providing performance model for the application, and hooks to stop application, checkpoint state, and re-start application. Based on MPI Programming Library, Globus Toolkit

Computer Science Department 13 Load Sharing in the Grid - 3 Before application begins, Application Manager runs performance model to predict execution times, number of processors. Determines whether an appropriate set of processors is available, schedules jobs Monitors process of application as it runs

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Computer Science Department 15 Load Sharing in the Grid - 4 Load sharing can occur if –Application progress is delayed –Additional resources become available App Manager sends message to application so it will –Checkpoint –Stop computation Re-start on new collection of nodes

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Computer Science Department 17 Research Directions Load sharing on the Grid: –There’s a large body of pre-Grid research of load balancing in distributed systems –Can the results of this research be used to design load balancing systems for the Grid

Computer Science Department 18 Load Balancing and Grid Computing David Finkel Computer Science Department Worcester Polytechnic Institute