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Annual International Symposium on computer Architecture, ISCA

作者： Ming-Syan Chen Kang G. Shin The University of Michigan Department of Electrical Engineering and Computer Science Real-Time Computing Laboratory University슠of슠Michigan Ann Arbor MI USA

Allocation and deallocation of subcubes usually result in a fragmented hypercube where even if a sufficient number of hypercube nodes are available, they do not form a subeube large enough to execute an incoming task. As the fragmentation in conventional memory allocation can be handled by memory compaction, the fragmentation problem in a hypercube can be solved by task migration, i.e., relocating tasks within the hypercubc to remove the fragmentation. The procedure for task migration closely depends on the subcube allocation strategy used, since active tasks must be relocated in such a way that the availability of subcubcs can be detected by that allocation strategy. In this paper, we develop a task migration strategy for the sub cube allocation policy based on the binary reflected Gray code. A goal configuration (of destination subeubes) without fragmentation is determined first. Then, the node-mapping between the source and destination subcubes is derived. Finally, a routing procedure to achieve shortest deadlock-free paths for relocating tasks is developed.

关键词： Hypercubes Permission Compaction Reflective binary codes Laboratories Routing System recovery Concurrent computing computer industry Encoding

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Evaluation of fault-tolerant systems with nonhomogeneous workloads

Evaluation of fault-tolerant systems with nonhomogeneous wor...

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International Symposium on Fault-Tolerant computing (FTCS)

作者： B.E. Aupperle J.F. Meyer L. Wei Computing Research Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

A methodology is presented for evaluating fault-tolerant systems when workloads and fault arrivals are not time-homogeneous. Of particular interests are systems whose environments vary considerably between different utilization phases of random duration. In such cases, evaluations of overall system performability must account for the corresponding differences in workload effects, especially with regard to fault recovery. The proposed methodology uses analytic techniques based on Markov processes and stochastic activity networks. Examples of evaluation studies, using this approach, are presented. These include evaluation of a system wherein self-exercising is varied between phases of passive and active use.< >

关键词： Fault tolerant systems Context modeling Performance evaluation Stochastic processes System performance Software measurement Markov processes Software reliability Software testing Hardware

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THE AEGIS DATA BUS EXPERIMENT

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NAVAL ENGINEERS JOURNAL 1989年第5期101卷 53-58页

作者： FRINK, JG VERVEN, DM John G. Frink is an assistant group supervisor in the Fleet Systems Department of The Johns Hopkins University Applied Physics Laboratory. He received his B.S. degree in physics from Michigan State University in 1968 and the M.S. degree in computer science from the University of Maryland in 1971. Mr. Frink worked at the Naval Surface Weapons Center White Oak Laboratory on a variety of weapons systems before joining the Applied Physics Laboratory in 1978. Mr. Frink has supervised the development of a large scale battle group simulation that successfully employs the receiver selection paradigm described herein on a hardware suite composed of an extensible number of (currently 15) processors. David M. Verven is a senior electrical engineer in the Fleet Systems Department of The Johns Hopkins University Applied Physics Laboratory. He received the B.S. degree in electrical engineering from the University of Maryland College Park in 1979 and the M. S. degree in the same discipline from The Johns Hopkins University in 1984. Mr. Verven joined the Applied Physics Laboratory in 1979 and initially worked on analysis of Navy sensor systems. In 1981 he was the AN/SPS-49 test team leader for the New Threat Upgrade (NTU) combat system land-based test. In 1982 he became involved in the development of the BBWRS system. Currently he is involved in real-time computer program development for the CEP project.

This paper documents an experiment performed by The Johns Hopkins University Applied Physics laboratory to measure the effect of inserting a data bus into a combat system. The experiment was conducted at the Aegis computer Center located at the Naval Surface Weapons Center in Dahlgren, Virginia (NSWC/DL). The purpose of the experiment was to determine whether or not the Aegis Weapon System (the core of the Aegis Combat System) could be operated with a portion of its point-to-point interelement cables replaced by a data bus. The data bus chosen for the experiment employs message broadcasting with receiver selection. A primary goal of the experiment was to minimize the amount of Aegis computer program changes required to accommodate the data bus. The results presented in this paper will show that the experiment was a success. Key certification tests were passed with no computer program changes to the tactical elements and minimal changes in the Aegis tactical executive (ATES) program (less than 110 words changed).

关键词： Data Transmission Equipment

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Hypercube management in the presence of node failures 3

Hypercube management in the presence of node failures

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3rd Conference on Hypercube Concurrent computers and Applications, C3P 1988

作者： Kandlur, Dilip D. Shin, Kang G. Real-time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109-2122 United States

ISBN: (纸本)0897912780

The problem of allocation and release of subcubes from a hypercube with node failures is addressed. Two algorithms are presented, both based on the Buddy allocation scheme for memory management which is also used by the AXIS operating system of the NCUBE hypercube computer. The first algorithm is a simple variation of the Buddy algorithm which permits the efficient allocation of subcubes in the presence of a single faulty node. The second algorithm, which effectively subsumes the first, tries to reduce the fragmentation caused by multiple failed nodes. It uses a relabeling scheme to group the failed nodes so that large non-faulty subcubes can be detected using the Buddy allocation scheme. The relative performance of these algorithms is studied using simulation and the proposed algorithms are shown to have a consistently better performance. Issues relating to the detection of faulty nodes on the NCUBE computer and the consequences of the relabeling on message passing are also discussed. © ACM 1988.

关键词： Message passing

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Embedding triple-modular redundancy into a hypercube architecture 3

Embedding triple-modular redundancy into a hypercube archite...

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3rd Conference on Hypercube Concurrent computers and Applications, C3P 1988

作者： Kiskis, Daniel L. Shin, Kang G. Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109-2122 United States

ISBN: (纸本)0897912780

This paper describes an embedding of Triple Modular Redundancy (TMR) into a binary hypercube. The goal is to improve fault tolerance by masking any single-point faults. Each module of an application task is triplicated and executed in parallel on three nodes of a 2-dimensional subcube (Q2) of the hypercube. Each of these nodes also executes a voter process. The remaining node is used for message passing only. All outputs from the triplicated modules are voted on, and the voting results are transmitted to the appropriate destination. Thus, all interunit messages are also triplicated. We propose an embedding of TMR into a hypercube which can be implemented in a manner transparent to the application program. Subcubes are allocated so that the address space for the TMR units is also a hypercube. Hence, the subcube allocation and intermodule communication schemes are defined to be analogous to the schemes used in the nonre-dundant system. The embedded system is proven to mask all single-point faults.

关键词： Message passing

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Message routing in an injured hypercube 3

Message routing in an injured hypercube

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3rd Conference on Hypercube Concurrent computers and Applications, C3P 1988

作者： Chen, Ming-Syan Shin, Kang G. Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109-2122 United States

ISBN: (纸本)0897912780

A connected hypercube containing faulty components (nodes or links) is called an injured hypercube. To enable non-faulty nodes to communicate with each other in an injured hypercube, the information of component failures must be made available to those non-faulty nodes for them to route messages around the faulty components. We develop a fault-tolerant routing scheme which requires each node to know only the information on the failure of its own links. Performance of this scheme is rigorously analyzed. This scheme is not only shown to be capable of routing messages successfully in injured hypercubes when the number of component failures is less than n, but also proved to be able to choose a shortest path with a very high probability.

关键词： Geometry

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Evaluation of the probability of dynamic failure and processor utilization for real-time systems

Evaluation of the probability of dynamic failure and process...

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real-time Systems Symposium (RTSS)

作者： M.H. Woodbury K.G. Shin Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

It is shown how to determine closed-form expressions for task scheduling delay and active task time distributions for any real-time system application, given a scheduling policy and task execution time distributions. The active task time denotes the total time a task is executing or waiting to be executed, including scheduling delays and resource contention delays. The distributions are used to determine the probability of dynamic failure and processor utilization, where the probability of dynamic failure is the probability that any task will not complete before its deadline. The opposing effects of decreasing the probability of dynamic failure and increasing utilization are also addressed. The analysis first addresses workloads where all tasks are periodic, i.e., they are repetitively triggered at constant frequencies. It is then extended to include the arrival of asynchronously triggered tasks. The effects of asynchronous tasks on the probability of dynamic failure and utilization are addressed.< >

关键词： real time systems Job shop scheduling Processor scheduling Optimal scheduling Application software Dynamic scheduling Delay effects Cost function Distributed computing Performance analysis

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Checkpointing and rollback recovery in a distributed system using common time base

Checkpointing and rollback recovery in a distributed system ...

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Reliable Distributed Systems

作者： P. Ramanathan K.G. Shin Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

An approach to checkpointing and rollback recovery in a distributed computing system using a common time base is proposed. First, a common time base is established in the system using a hardware clock synchronization algorithm. This common time base is coupled with a pseudorecovery block approach to develop a checkpointing algorithm that has the following advantages: (i) maximum process autonomy, (ii) no wait for commitment for establishing recovery lines, (iii) fewer messages to be exchanged, and (iv) less memory requirement.< >

关键词： Checkpointing Testing real time systems Clocks Synchronization Broadcasting Laboratories Distributed computing Hardware Fault tolerant systems

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Effects of computing time Delay on real-time Control Systems

Effects of Computing Time Delay on Real-Time Control Systems

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American Control Conference (ACC)

作者： Kang G. Shin Xianzhong Cui Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

The reliability of a real-time digital control system depends not only on the reliability of the hardware and software used, but also on the speed in executing control algorithms. The latter is due to the negative effects of computing time delay on control system performance. For a given sampling interval, the effects of computing time delay are classified into the delay problem and the loss problem. Analysis of these two problems is presented as a means of evaluating real-time control systems. As an example, both the self-tuning predicted (STP) control and Proportional-Integral-Derivative (PID) control are applied to the problem of tracking robot trajectories, and their respective effects of computing time delay on control performance are comparatively evaluated. For this exmple, the STP (PID) controller is shown to outperform the PID (STP) controller in coping with the delay (loss) problem.

关键词： Delay effects real time systems Control systems Pi control Proportional control Three-term control Digital control Hardware Software algorithms System performance

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Design and scheduling of mesh array of hardware unifiers for large-scale unification 1st

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1st International Conference on Supercomputing, 1987

作者： Shih, Yifong Irani, Keki B. Computing Research Laboratory Department of Electrical Engineering and Computer Science The University of Michigan Ann ArborMI48109 United States

ISBN: (纸本)9783540189916

We propose a hardware unification array consisting of k × n fourconnected unification units to be used to speed up the process of finding suitable bindings for common variables among the predicates in a logic program. Four different algorithms (SIMPLEX, PCC, PwFLP and CP) to perform unification in the array are presented and their performances compared. The final level of unification in scheduling multiple arrays is found to be the most expensive, deserving the highest degree of hardware support. © 1988, Springer-Verlag.

关键词： Scheduling

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