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International Symposium on High Performance Distributed computing

作者： A. Choudhary M. Kandemir H. Nagesh J. No X. Shen V. Taylor S. More R. Thakur Center for Parallel and Distributed Computing Department of Electrical and Computer Engineering Northwestern University Evanston IL USA Mathematics and Computer Science Division Argonne National Laboratory Argonne IL USA

With the increasing number of scientific applications manipulating huge amounts of data, effective data management is an increasingly important problem. Unfortunately, so far the solutions to this data management problem either require deep understanding of specific storage architectures and file layouts (as in high-performance file systems) or produce unsatisfactory I/O performance in exchange for ease-of-use and portability (as in relational DBMSs). In this paper we present a new environment which is built around an active meta-data management system (MDMS). The key components of our three-tiered architecture are user application, the MDMS, and a hierarchical storage system (HSS). Our environment overcomes the performance problems of pure database-oriented solutions, while maintaining their advantages in terms of ease-of-use and portability. The high levels of performance are achieved by the MDMS, with the aid of user-specified directives. Our environment supports a simple, easy-to-use yet powerful user interface, leaving the task of choosing appropriate I/O techniques to the MDMS. We discuss the importance of an active MDMS and show how the three components, namely application, the MDMS, and the HSS, fit together. We also report performance numbers from our initial implementation and illustrate that significant improvements are made possible without undue programming effort.

关键词： Large-scale systems Distributed computing High performance computing Data visualization engineering management Concurrent computing Relational databases Art Data analysis Image analysis

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Experiments on six commercial TCP implementations using a software fault injection tool†

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Software: Practice and Experience 1999年第12期27卷

作者： Scott Dawson Farnam Jahanian Todd Mitton Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109-2122 USA

TCP, the de facto standard transport protocol in today's operating systems, is a very robust protocol that adapts to various network characteristics, packet loss, link congestion, and even significant differences in vendor implementations. This paper describes a set of experiments performed on six different vendor TCP implementations using ORCHESTRA, a tool for testing and fault injection of communication protocols. These experiments uncovered violations of the TCP protocol specification, and illustrated differences in the philosophies of various vendors in their implementations of TCP. The paper summarizes several lessons learned about the TCP implementations through these experiments. © 1997 John Wiley & Sons, Ltd.

关键词： TCP distributed systems communication protocols fault injection tool protocol testing

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Proteus: a flexible infrastructure to implement adaptive fault tolerance in AQuA

Proteus: a flexible infrastructure to implement adaptive fau...

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Dependable computing for Critical Applications 7

作者： C. Sabnis M. Cukier J. Ren P. Rubel W.H. Sanders D.E. Bakken D. Karr Center of Reliable and High-Performance Computing Coordinated Science Laboratory and Department of Electrical and Computer Engineering University of Illinois Urbana IL USA BBN Technologies GTE Cambridge MA USA

Building dependable distributed systems from commercial off-the-shelf components is of growing practical importance. For both cost and production reasons, there is interest in approaches and architectures that facilitate building such systems. The AQuA architecture is one such approach; its goal is to provide adaptive fault tolerance to CORBA applications by replicating objects, providing a high-level method for applications to specify their desired dependability, and providing a dependability manager that attempts to reconfigure a system at runtime so that dependability requests are satisfied. This paper describes how dependability is provided in AQuA. In particular it describes Proteus, the part of AQuA that dynamically manages replicated distributed objects to make them dependable. Given a dependability request, Proteus chooses a fault tolerance approach and reconfigures the system to try to meet the request. The infrastructure of Proteus is described in this paper, along with its use in implementing active replication and a simple dependability policy.

关键词： Fault tolerance Quality of service Buildings Application software Costs Fault tolerant systems Hardware Contracts Distributed computing High performance computing

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Building dependable distributed applications using AQUA

Building dependable distributed applications using AQUA

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IEEE International Symposim on High Assurance Systems engineering

作者： J. Ren M. Cukier P. Rubel W.H. Sanders D.E. Bakken D.A. Karr Center for Reliable and High-Performance Computing Coordinated Science Laboratory and Department of Electrical and Computer Engineering University of Illinois Urbana IL USA BBN Technologies GTE Cambridge MA USA

Building dependable distributed systems using ad hoc methods is a challenging task. Without proper support, an application programmer must face the daunting requirement of having to provide fault tolerance at the application level, in addition to dealing with the complexities of the distributed application itself. This approach requires a deep knowledge of fault tolerance on the part of the application designer, and has a high implementation cost. What is needed is a systematic approach to providing dependability to distributed applications. Proteus, part of the AQuA architecture, fills this need and provides facilities to make a standard distributed CORBA application dependable, with minimal changes to an application. Furthermore, it permits applications to specify, either directly or via the Quality Objects (QuO) infrastructure, the level of dependability they expect of a remote object, and will attempt to configure the system to achieve the requested dependability level. Our previous papers have focused on the architecture and implementation of Proteus. This paper describes how to construct dependable applications using the AQuA architecture, by describing the interface that a programmer is presented with and the graphical monitoring facilities that it provides.

关键词： electrical capacitance tomography Fault tolerance Buildings Application software Quality of service Contracts Hardware Runtime Object detection Tellurium

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Cross-positive vector fields: directed stability

Cross-positive vector fields: directed stability

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IEEE Conference on Decision and Control

作者： D.G. Meyer T.L. Piatt A.P. Engelmann J. Hauser Dept. of Electr. & Comput. Eng. Colorado Univ. Boulder CO USA Nonlinear and Real-Time Control Laboratory Electrical & Computer Engineering Department University of Colorado Boulder CO USA University of Colorado Boulder Boulder CO US

Builds on the previous work by the authors (1998) by defining local versions of cross-positivity for vector fields, especially as related to shifted cones. The paper also furthers the development of a stability theory by introducing preliminary concepts of directed stability. The motivation is to apply this theory to analyzing the control of certain directionally constrained models, such as those found in materials processing.

关键词： Materials processing

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Performance evaluation of packet discard schemes in ATM switches in heterogeneous traffic environment

Performance evaluation of packet discard schemes in ATM swit...

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IEEE International Conference on ATM

作者： Z. Jing H. Sun L. Li National Key Laboratory of Optical Fiber Communication University of Electronic Science and Technology Chengdu Sichuan China Center for Advanced Computing and Communications Department of Electrical and Computer Engineering Duke University Durham NC USA

In this paper, we study the performance of different packet discard schemes in ATM switches in a heterogeneous traffic environment. The throughput, fairness and delay characteristics of different packet discard schemes are studied in the environment of heterogeneous traffic and in the environment of fixed and time-varying available bandwidth. Through performance comparison, we show that the queuing system with EPD (early packet discard) algorithm gives higher goodput to the sources near it, and the sources far away from the system have lower goodput. It is necessary to integrate the RED (random early detection) algorithm with the EPD algorithm and the RED+EPD algorithm can provide relatively fair goodput to heterogeneous traffic. An ATM switch with the RED+EPD algorithm can provide higher throughput, better fairness and smaller delay than the EPD algorithm, so it can support the traffic with delay requirement.

关键词： Asynchronous transfer mode Packet switching Switches Traffic control Communication switching Delay Throughput Telecommunication traffic TCPIP Optical packet switching

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Comparison of connection admission-control schemes in the presence of hand-offs in cellular networks 98

Comparison of connection admission-control schemes in the pr...

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4th Annual ACM/IEEE International Conference on Mobile computing and Networking, MobiCom 1998

作者： Choi, Sunghyun Shin, Kang G. Real-Time Computing Laboratory Department Of Electrical Engineering And Computer Science The University Of Michigan Ann ArborMI48109-2122 United States

ISBN: (纸本)9781581130355

In this paper, we compare four distributed connection admission control schemes in cellular networks where the first two schemes are to keep the hand-off dropping probability below a target value, the third scheme is to guarantee no hand-off drops through a per-connection bandwidth reservation, and the fourth scheme uses another type of per-connection bandwidth reservation. The first scheme predicts the bandwidth required to handle hand-offs by estimating possible hand-offs from adjacent cells, then performs the admission control for each newly-requested connection. On the other hand, the second scheme predicts the total required bandwidth in the current cell by estimating both incoming and outgoing hand-offs at each cell. The third scheme requires the set of cells which the mobile with a newly-requested connection will traverse, and reserves bandwidth for each connection in each of those cells. The fourth scheme reserves bandwidth for each connection in the predicted next cell of a mobile. We adopt the history-based mobility estimation for the first two schemes. Using extensive simulations, the four schemes are compared quantitatively in terms of (1) important performance measures such as the hand-off dropping probability, connection-blocking probability, and bandwidth utilization, (2) dependency on the de-sign parameters, (3) dependency on the mobility estimation accuracy, and (4) complexity. The simulation results indicate that the first scheme is the most desirable in the sense that it achieves reasonably good performance while requiring much less memory and computation than the other three schemes. © Copyright ACM 1998.

关键词： Bandwidth

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Trajectory morphing for nonlinear systems

Trajectory morphing for nonlinear systems

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1998 American Control Conference, ACC 1998

作者： Hauser, John Meyer, David G. Nonlinear and Real-Time Control Laboratory Electrical and Computer Engineering Department University of Colorado Boulder CO 80309-0425 United States

In this paper nonlinear trajectory morphing is introduced. We show how it can explore the trajectory space of a nonlinear system. A trajectory tracking projection operator is defined for practical implementation of mo... 详细信息

ISBN: (纸本)0780345304

关键词： Nonlinear systems

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Predictive and adaptive bandwidth reservation for hand-offs in QoS-sensitive cellular networks 98

Predictive and adaptive bandwidth reservation for hand-offs ...

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Proceedings of the ACM SIGCOMM '98 conference on Applications, technologies, architectures, and protocols for computer communication

作者： Sunghyun Choi Kang G. Shin Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science The University of Michigan Ann Arbor Michigan

ISBN: (纸本)9781581130034

How to control hand-off drops is a very important Quality-of-Service (QoS) issue in cellular networks. In order to keep the hand-off dropping probability below a pre-specified target value (thus providing a probabilistic QoS guarantee), we design and evaluate predictive and adaptive schemes for the bandwidth reservation for the existing connections' handoffs and the admission control of new *** first develop a method to estimate user mobility based on an aggregate history of hand-offs observed in each cell. This method is then used to predict (probabilistically) mobiles' directions and hand-off times in a cell. For each cell, the bandwidth to be reserved for hand-offs is calculated by estimating the total sum of fractional bandwidths of the expected hand-offs within a mobility-estimation time window. We also develop an algorithm that controls this window for efficient use of bandwidth and effective response to (1) time-varying traffic/mobility and (2) inaccuracy of mobility estimation. Three different admission-control schemes for new connection requests using this bandwidth reservation are proposed. Finally, we evaluate the performance of the proposed schemes to show that they meet our design goal and outperform the static reservation scheme under various scenarios.

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Optimization of a real-time primary-backup replication service

Optimization of a real-time primary-backup replication servi...

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Reliable Distributed Systems

作者： Hengming Zou F. Jahanian Real-time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

The primary-backup replication model is one of the commonly adopted approaches to providing fault tolerant data services. Its extension to the real time environment, however, imposes the additional constraint of timing predictability, which requires a bounded overhead for managing redundancy. The paper discusses the trade-off between reducing system overhead and increasing (temporal) consistency between the primary and backup, and explores ways to optimize such a system to minimize either the inconsistency or the system overhead while maintaining the temporal consistency guarantees of the system. An implementation built on top of the existing RTPB model (H. Zou and F. Jahanian, 1998) was developed within the x-kernel architecture on the Mach OSF platform running MK 7.2. Results of an experimental evaluation of the proposed optimization techniques are discussed.

关键词： Fault tolerance Timing Redundancy Fault tolerant systems real time systems Laboratories Environmental management Buildings Protocols Application software

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