Appears in the 10th International Parallel Processing Symposium ECO: Efficient Collective Operations forCommunication on Heterogeneous Networks

Abstract PVM and other distributed computing systems have enabled the use of networks of work-stations for parallel computation, but their approach of treating all networks as collections o

Appears in Grid 2003 c○2003 IEEE Comparing Passive Network Monitoring of Grid Application Traffic with Active Probes

Distributed applications require timely network measurements so that they can adapt to changing network conditions and make efficient use of grid resources. One of the key issues in obtaining network measurements is the intrusiveness of the measurements themselves—how much network performance is “wasted ” taking the measurements? Our goal is to combine active and passive monitoring techniques to reduce the need for intrusive measurements without sacrificing the accuracy of the measurements. We are developing a bandwidth monitoring tool as part of the Wren network measurement system that will reduce the burden on the network by passively obtaining measurements from existing application traffic whenever possible, instead of actively probing the network. By using passive measurements when an application is running and active measurements when none are running, we can offer accurate, timely available bandwidth measurements while limiting the invasiveness of active probes. We have completed a prototype of the Wren bandwidth monitoring tool and present our preliminary analysis of its performance in this paper. We provide results from passive implementations of several available bandwidth techniques and demonstrate the close quantitative relationship between the results of both active and passive techniques. We have tested our implementation in a cluster, across a campus, and across the Internet using bulk data transfers as well as an adaptive eigenvalue application. Our results with this diverse set of environments and traffic types show promise toward implementing these techniques as measurement services in production environments

ECO: Efficient Collective Operations for Communication on Heterogeneous Networks

PVM and other distributed computing systems have enabled the use of networks of workstations for parallel computation, but their approach of treating a network as a collection of point-to-point connections does not promote efficient communication--- particularly collective communication. ECO is a package which solves this problem with programs which analyze the network and establish efficient communication patterns which are used by a library of collective operations. The analysis is done off-line, so that after paying the one-time cost of analyzing the network, the execution of application programs is not delayed. This paper gives performance results from using ECO to implement the collective communication in CHARMM, a widely used macromolecular dynamics package. ECO facilitates the development of data parallel applications by providing a simple interface to routines which use the available heterogeneous networks efficiently. This approach gives a naive programmer the abili..

Appears in Grid 2003 c○2003 IEEE Enabling Network Measurement Portability Through a Hierarchy of Characteristics

Measurement and prediction of network resources are crucial so that adaptive applications can make use of Grid environments. Although a large number of systems and tools have been developed to provide such measurement services, the diversity of Grid resources and lack of central control prevent the development of a single monitoring system that can be deployed to answer every application’s resource queries for connections between any pair of machines it can use. We propose a standard for representing network entities and measurements of their properties. Our standard enables the exchange of measurements and will allow applications to function even in environments without the particular measurement system for which they were developed. We present an overview of our measurement representation and evaluate its usefulness. We have used the characteristics hierarchy to store and exchange measurement data between several systems, and we discuss its usefulness in comparing the output of several measurement tools. 1

Transparent Optimization of Grid Server Selection With Real-Time Passive

Grid services have tremendously simplified the programming challenges in leveraging large-scale distributed computing. At the same time, the increased level of abstraction reduces the opportunities available to the application for optimizing its performance by monitoring the system. In this paper we introduce a monitoring grid services proxy, which transparently monitors network performance and selects between several replica service providers. This approach provides optimized server selection without any modification to or even awareness of the client application or service providers. We describe how we implement the proxy and monitor the available bandwidth to the service providers using the Wren monitoring toolkit. We present analysis indicating that our monitoring has negligible overhead. Finally, we demonstrate the practicality of our approach by optimizing the server selection for INCOGEN’s VIBE, a bioinformatics workflow application that uploads gene sequences for analysis by remote service providers. We would like to thank INCOGEN for allowing us to use their VIBE software toolkit. In particular, w

The Cellular Automata Paradigm for the Parallel Solution of HeatTransfer Problems

This paper describes the numerical solution of heat transfer problems using cellular automata. While traditional methods offer high performance on uniprocessor machines, their performance is limited on distributed memory multiprocessors by communication bottlenecks caused by the interdependence of the equations. Using a cellular automata formulation, these bottlenecks can be avoided, and performance greater than that obtained by parallelizing traditional algorithms can be achieved. This paper gives an overview of the cellular automata paradigm and specific examples of solutions to a hyperbolic and a parabolic problem. The accuracy of the method is verified by comparisons of the results with analytical solutions and with results produced by other techniques