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Möbius: An extensible tool for performance and dependability modeling 11th

Möbius: An extensible tool for performance and dependabilit...

11th International Conference on Modelling Tools and Techniques for computer and Communication System Performance Evaluation, TOOLS 2000

作者： Daly, David Deavours, Daniel D. Doyle, Jay M. Webster, Patrick G. Sanders, William H. Center for Reliable and High-Performance Computing Coordinated Science Laboratory and Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign 1308 W. Main St UrbanaIL United States

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Minimizing the maximum end-to-end delay on tree structure using the distributed pinwheel model

Minimizing the maximum end-to-end delay on tree structure us...

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IEEE International Conference on Embedded and real-time computing Systems and Applications (RTCSA)

作者： Yu-Sheng Huang Chih-Wen Hsueh Real-Time Systems Laboratory Department of Computer Science and Information Engineering National Chung Cheng University Chiayi Taiwan

Distributed real-time systems often have some end-to-end timing requirements. Minimizing the maximum end-to-end delay is one of the most important timing constraints we would like to guarantee for quality of services. The network topology of many distributed systems on Internet is often a tree structure. In this paper, we extend our research on distributed pinwheel scheduling from pipeline structure to tree structure for minimizing the maximum end-to-end delay. We derive a tight maximum delay bound between two nodes and a linear-time algorithm to find the minimax delay between two nodes. With this bound and algorithm, it is easier and faster to schedule distributed real-time tasks with distance constraints and minimize the maximum end-to-end delay. Since the general scheduling problem is very difficult (NP-hard), we derive a more efficient heuristic algorithm than previous researches to minimize the maximum end-to-end delay. We also compare the simulation results of our heuristic and previous researches. The distributed pinwheel scheduling model can be used for distance-constrained real-time tasks on tree structure to reduce a lot of the maximum end-to-end delay and provide a predictable result.

关键词： Delay Tree data structures Timing Scheduling algorithm real time systems Quality of service Network topology IP networks Pipelines Minimax techniques

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Concurrency control in a multiprocessor real-time database system

Concurrency control in a multiprocessor real-time database s...

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Euromicro Conference on real-time Systems

作者： Tei-Wei Kuo Hsin-Chia Hsih Real-Time and Embedded System Laboratory Department of Computer Science and Information Engineering National Chung Cheng University Chiayi Taiwan

ISBN: (纸本)0769507344

Although many high-performance computer systems are now multiprocessor-based, little work has been done in real-time concurrency control of transaction executions in a multiprocessor environment. A real-time concurrency control protocol designed for uniprocessor or distributed environments may not fit the needs of multiprocessor-based real-time database systems because of a lower degree of concurrency of the transaction executions and a larger number of priority inversions. This paper proposes the concept of a priority cap to bound the maximum number of priority inversions in multiprocessor-based real-time database systems to meet transaction deadlines and to explore the abundant computing resources of parallel computer systems. A series of experiments is conducted to evaluate the capability of the proposed methodology in scheduling real-time transactions in a parallel fashion.

关键词： Concurrency control real time systems Database systems Concurrent computing Protocols Transaction databases Processor scheduling Distributed databases System performance Embedded system

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Dynamic component substitution in Web-based simulation

Dynamic component substitution in Web-based simulation

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Simulation Winter Conference

作者： D.M. Rao P.A. Wilsey Experimental Computing Laboratory Department of Electrical and Computer Engineering & Computer Science University of Cincinnati Cincinnati OH USA

Recent breakthroughs in communication and software engineering has resulted in significant growth of Web-based computing. Web-based techniques have been employed for modeling, simulation and analysis of systems. The models for simulation are usually developed using component based techniques. In a component based model, a system is represented as a set of interconnected components. A component is a well defined software module that is viewed as a black box, i.e., only its interface is of concern and not its implementation. However, the behavior of a component, which is necessary for simulation, could be implemented by different modelers including third party manufacturers. Web-based simulation environments enable effective sharing and reuse of components thereby minimizing model development overheads. In component based simulations, one or more components can be substituted during simulation with a functionally equivalent set of components. Such dynamic component substitutions (DCS) provide an effective technique for selectively changing the level of abstraction of a model during simulation. It provides a tradeoff between simulation overheads and model details. It can be used to effectively study large systems and accelerate rare event simulations to desired scenarios of interest. DCS may also be used to achieve fault-tolerance in Web-based simulations. This paper presents the ongoing research to design and implement support for DCS in a Web-based Environment for Systems engineering (WESE).

关键词： Computational modeling Distributed control Software engineering Analytical models Virtual manufacturing Acceleration Discrete event simulation Fault tolerance Design engineering Systems engineering and theory

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Data management for large‐scale scientific computations in high performance distributed systems

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Cluster computing 2000年第1期3卷 45-60页

作者： Choudhary, A. Kandemir, M. No, J. Memik, G. Shen, X. Liao, W. Nagesh, H. More, S. Taylor, V. Thakur, R. Stevens, R. Center for Parallel and Distributed Computing Department of Electrical and Computer Engineering Northwestern University Evanston USA Department of Computer Science and Engineering The Pennsylvania State University University Park USA Mathematics and Computer Science Division Argonne National Laboratory Argonne USA

With the increasing number of scientific applications manipulating huge amounts of data, effective high-level data management is an increasingly important problem. Unfortunately, so far the solutions to the high‐level data management problem either require deep understanding of specific storage architectures and file layouts (as in high-performance file storage 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 novel application development environment which is built around an active meta-data management system (MDMS) to handle high-level data in an effective manner. 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, performance-oriented directives. Our environment supports a simple, easy-to-use yet powerful user interface, leaving the task of choosing appropriate I/O techniques for the application at hand to the MDMS. We discuss the importance of an active MDMS and show how the three components of our environment, namely the application, the MDMS, and the HSS, fit together. We also report performance numbers from our ongoing implementation and illustrate that significant improvements are made possible without undue programming effort.

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An efficient algorithm for the physical mapping of clustered task graphs onto multiprocessor architectures

An efficient algorithm for the physical mapping of clustered...

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Euromicro Workshop on Parallel and Distributed Processing

作者： N. Koziris M. Romesis P. Tsanakas G. Papakonstantinou Department of Electrical and Computer Engineering Computer Science Division Computing Systems Laboratory National and Technical University of Athens Zografou Greece

The most important issue in sequential program parallelisation is the efficient assignment of computations into different processing elements. In the past, too many approaches were devoted in efficient program parallelization considering various models for the parallel programs and the target architectures. The most widely used parallelism description model is the task graph model with precedence constraints. Nevertheless, as far as physical mapping of tasks onto parallel architectures is concerned little research has given practical results. It is well known that the physical mapping problem is NP-hard in the strong sense, thus allowing only for heuristic approaches. Most researchers or tool programmers use exhaustive algorithms, or the classical method of simulated annealing. This paper presents an alternative approach onto the mapping problem. Given the graph of clustered tasks, and the graph of the target distributed architecture, our heuristic finds a mapping by first placing the highly communicative tasks on adjacent nodes of the processor network. Once these "backbone" tasks are mapped there is no backtracking, thus achieving low complexity. Therefore, the remaining tasks are placed beginning from those close to the "backbone" tasks. The paper concludes with performance and comparison results which reveal the method's efficiency.

关键词： Clustering algorithms Processor scheduling Network topology computer networks Application software Costs computer architecture computer science Laboratories Electronic mail

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Amplitude alterations between sinus rhythm and ventricular tachycardia or ventricular fibrillation in surface and intracardiac leads in human subjects

Amplitude alterations between sinus rhythm and ventricular t...

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computers in Cardiology (CinC)

作者： G. Altvater J.M. Jenkins M.P. Biersack J.A. Thompson Medical Computing Laboratory Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA

This study was performed to quantify the electrocardiographic amplitude alterations that occur in the transition from sinus rhythm (SR) to ventricular tachycardia (VT) or ventricular fibrillation (VF) in human subjects. Measurements were made of QRS complexes on surface ECGs and of intraventricular depolarizations. Patients were studied in three categories: Group A (no drugs), Group B (Amiodarone), and Group C (Procainamide). In ventricular tachycardia the authors found increases in every lead in all three groups. Lead I increases ranged from 12-52%; in Lead III increases were 49-148%; in Lead VI Increases were 20-54%. Ventricular tachycardia measured from the right ventricular apex (RVA) showed increases ranging from 24-49%. In ventricular fibrillation, amplitudes exhibited both increases and decreases in Leads I and VI, and increases in Lead III. In the RVA, ventricular fibrillation amplitude decreased in all three groups, ranging from -2-55%. Results of VF for Amiodarone and Procainamide are inconclusive doe to the small patient sample size. The data show that there is a significant increase in VT amplitude over SR, as well as a relationship in VT amplitudes between drug and no drug groups in every lead Also, VF was characterized by decreased amplitudes or markedly smaller increases than VT.

关键词： Rhythm Fibrillation Drugs Strontium Humans Biomedical computing Laboratories Electrocardiography Heart rate Cardiology

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Distributed expertise for teaching computer organization & architecture 00

Distributed expertise for teaching computer organization & a...

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Working Group Reports from 5th Annual Conference on Innovation and Technology in computer science Education, ITiCSE-WGR 2000

作者： Cassel, Lillian Boots Kumar, Deepak Bolding, Kevin Davies, Jim Holliday, Mark Impagliazzo, John Pearson, Murray Wolffe, Gregory S. Yurcik, William Department of Computing Sciences Villanova University VillanovaPA United States Department of Mathematics and Computer Science Bryn Mawr College Bryn MawrPA United States Department of Electrical Engineering Seattle Pacific University SeattleWA United States Computing Laboratory University of Oxford Oxford United Kingdom Department of Mathematics and Computer Science Western Carolina University CullowheeNC United States Department of Computer Science Hofstra University HempsteadNY United States Department of Computer Science University of Waikato Hamilton New Zealand Department of Computer Science and Information Systems Grand Valley State University AllendaleMI United States Department of Applied Computer Science Illinois State University NormalIL United States

ISBN: (纸本)9781450373586

This report presents preliminary results from our project on creating distributed expertise for teaching computer organization & architecture course(s) in the undergraduate computer science curriculum. We present the details of an online survey designed to gather information from faculty on the current state of teaching this course. The survey also tries to identify specific areas of need for creating distributed expertise as reported by various faculty. We also present several resources that have been identified that are available for use by faculty teaching the course(s). This report represents a mid-point of an ongoing two-year study. Following a discussion of the currently identified needs, we discuss ways to address them and conclude the report with a plan of action that will follow in the next phase of the project.

关键词： Teaching

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DC/sup 2/ scheduling for aperiodic tasks in strongly partitioned real-time systems

DC/sup 2/ scheduling for aperiodic tasks in strongly partiti...

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IEEE International Conference on Embedded and real-time computing Systems and Applications (RTCSA)

作者： Daeyoung Kim Yann-Hang Lee Real Time Systems Research Laboratory CISE Department University of Florida Gainesville FL USA Department of Computer Science and Engineering Arizona State University Tempe AZ USA

The strongly partitioned real time system (SP-RTS) provides temporal and spatial partitioning for its integrated real time applications. The SP-RTS architecture adopts a two-level hierarchical scheduling mechanism. In the lower level, multiple partitions (applications) are dispatched under a cyclic scheduling, whereas, in the higher level, multiple periodic tasks of each partition are scheduled according to a fixed priority algorithm. The authors focus on designing algorithms for online scheduling of aperiodic tasks in the SP-RTS environment. The Distance Constraint guaranteed Dynamic Cyclic (DC/sup 2/) scheduler that is proposed uses these basic operations: Left Sliding (LS), Right Putting (RP), and Compacting. These operations dynamically schedule aperiodic tasks within a distance-constrained cyclic schedule. We show that the dynamic applications of these operations do not violate the distance constraint characteristics of a partition cyclic schedule. In addition, the slack time calculation of these dynamic operations can be applied for scheduling hard aperiodic tasks. With the simulation studies, we observed that the DC/sup 2/ can result in a significant performance enhancement in terms of the average response time of soft aperiodic tasks and the acceptance rate for hard aperiodic tasks.

关键词： real time systems Dynamic scheduling Partitioning algorithms Scheduling algorithm Algorithm design and analysis Aerospace electronics Application software Processor scheduling Laboratories Computational modeling

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Loki: a state-driven fault injector for distributed systems

Loki: a state-driven fault injector for distributed systems

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International Conference on Dependable Systems and Networks (DSN)

作者： R. Chandra R.M. Lefever M. Cukier W.H. Sanders Center for Reliable and High-Performance Computing Coordinated Science Laboratory and Department of Electrical and Computer Engineering University of Illinois Urbana-Champaign Urbana IL USA

Distributed applications can fail in subtle ways that depend on the state of multiple parts of a system. This complicates the validation of such systems via fault injection, since it suggests that faults should be injected based on the global state of the system. In Loki, fault injection is performed based on a partial view of the global state of a distributed system, i.e. faults injected in one node of the system can depend on the state of other nodes. Once faults are injected, a post-runtime analysis, using off-line clock synchronization, is used to place events and injections on a single global timeline and to determine whether the intended faults were properly injected. Finally, experiments containing successful fault injections are used to estimate the specified measures. In addition to briefly reviewing the concepts behind Loki and its organization, we detail Loki's user interface. In particular, we describe the graphical user interfaces for specifying state machines and faults, for executing a campaign and for verifying whether the faults were properly injected.

关键词： Synchronization Clocks Distributed computing Application software User interfaces Graphical user interfaces Cost accounting Contracts Particle measurements Runtime

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