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2010 IEEE 18th International Workshop on Quality of Service, IWQoS 2010

作者： Chen, Fajun Liu, Jiangchuan Li, Zongpeng Wang, Yijie Key Laboratory of Science and Technology for National Defence of Parallel and Distributed Processing School of Computer National University of Defense Technology China School of Computing Science Simon Fraser University Canada Department of Computer Science University of Caglary Canada

ISBN: (纸本)9781424459889

Existing routing protocols for Wireless Mesh Networks (WMNs) are generally optimized with statistical link measures, while not addressing on the intrinsic uncertainty of wireless links. We show evidence that, with the transient link uncertainties at PHY and MAC layers, a pseudo-deterministic routing protocol that relies on average or historic statistics can hardly explore the full potentials of a multi-hop wireless mesh. We study optimal WMN routing using probing-based online anypath forwarding, with explicit consideration of transient link uncertainties. We show the underlying connection between WMN routing and the classic Canadian Traveller Problem (CTP) [1]. Inspired by a stochastic recoverable version of CTP (SRCTP), we develop a practical SRCTP-based online routing algorithm under link uncertainties. We study how dynamic next hop selection can be done with low cost, and derive a systematic selection order for minimizing transmission delay. We conduct simulation studies to verify the effectiveness of the SRCTP algorithms under diverse network configurations. In particular, compared to deterministic routing, reduction of end-to-end delay (51:15∼73:02%) and improvement on packet delivery ratio (99:76%) are observed.

关键词： Routing protocols

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Evolving agent-based simulations in the clouds

Evolving agent-based simulations in the clouds

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3rd International Workshop on Advanced Computational Intelligence, IWACI 2010

作者： Decraene, James Cheng, Yong Yong Hean Low, Malcolm Yoke Zhou, Suiping Cai, Wentong Choo, Chwee Seng Parallel and Distributed Computing Center School of Computer Engineering Nanyang Technological University Singapore Singapore DSO National Laboratories 20 Science Park Drive Singapore Singapore

ISBN: (纸本)9781424463343

Evolving agent-based simulations enables one to automate the difficult iterative process of modeling complex adaptive systems to exhibit pre-specified/desired behaviors. Nevertheless this emerging technology, combining research advances in agent-based modeling/simulation and evolutionary computation, requires significant computing resources (i.e., high performance computing facilities) to evaluate simulation models across a large search space. Moreover, such experiments are typically conducted in an infrequent fashion and may occur when the computing facilities are not fully available. The user may thus be confronted with a computing budget limiting the use of these "evolvable simulation" techniques. We propose the use of the cloud computing paradigm to address these budget and flexibility issues. To assist this research, we utilize a modular evolutionary framework coined CASE (for complex adaptive system evolver) which is capable of evolving agent-based models using nature-inspired search algorithms. In this paper, we present an adaptation of this framework which supports the cloud computing paradigm. An example evolutionary experiment, which examines a simplified military scenario modeled with the agent-based simulation platform MANA, is presented. This experiment refers to Automated Red Teaming: a vulnerability assessment tool employed by defense analysts to study combat operations (which are regarded here as complex adaptive systems). The experimental results suggest promising research potential in exploiting the cloud computing paradigm to support computing intensive evolvable simulation experiments. Finally, we discuss an additional extension to our cloud computing compliant CASE in which we propose to incorporate a distributed evolutionary approach, e.g., the island-based model to further optimize the evolutionary search.

关键词： Cloud computing

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A hierarchical processor scheduling policy for distributed-memory multicomputer systems

A hierarchical processor scheduling policy for distributed-m...

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International Conference on High Performance computing

作者： S.P. Dandamudi T.K. Thyagaraj Centre for Parallel and Distributed Computing School of Computer Science Carleton University Ottawa ONT Canada

Processor scheduling policies for distributed memory systems can be divided into space sharing or time sharing policies. In space sharing, the set of processors in the system is partitioned and each partition is assigned for the exclusive use of a job. In time sharing policies, on the other hand, none of the processors is given exclusively to jobs; instead, several jobs share the processors (for example, in a round robin fashion). There are advantages and disadvantages associated with each type of policy. Typically, space sharing policies are good at low to moderate system loads and when job parallelism does not vary much. However, at high system loads and widely varying job parallelism, time sharing policies provide a better performance. We propose a new policy that is based on a hierarchical organization that incorporates the merits of these two types of policies. The new policy is a hybrid policy that uses both space sharing as well as time sharing to achieve better performance. We demonstrate that, at most system loads of interest, the proposed policy outperforms both space sharing and time sharing policies by a wide margin.

关键词： Processor scheduling Time sharing computer systems Round robin parallel processing distributed computing computer science Large-scale systems Concurrent computing Message passing Delay

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Rule Execution in a Service-Oriented Architecture for distributed Simulation on the Grid

Rule Execution in a Service-Oriented Architecture for Distri...

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Asia Simulation conference 2008/the 7th International Conference on System Simulation and Scientific computing（ICSC‘2008）

作者： Stephen John Turner Computer Science and Director of the Parallel and Distributed Computing Centre of the School of Computer Engineering Nanyang Technological University

Nowadays, more researchers in the simulation field are interested in the use of a service-oriented architecture and component-based system in order to design more efficient large-scale distributed simulation systems. A Service-Oriented Architecture (SOA) is a collection of independent services with well-defined interfaces that can be accessed without knowledge of their implementation. A component-based approach separates the whole system into different parts based on their functionalities. In this paper, a framework for component-based distributed simulation on the Grid (SOAr-DSGrid) is introduced. One of the major issues in designing the framework is to have efficient data FLow and control flow in the framework. Data flow describes the way that data moves in the system while control flow determines the order of activities that happen in the system. The rule engine is a critical part of the framework and is responsible for managing the distributed data flow and control FLow. The design and implementation of the rule engine is the major focus of this paper. The rule engine enables the framework to be more scalable as the components within the framework now communicate in a fully distributed manner.

关键词： Rule Execution in a Service-Oriented Architecture for distributed Simulation on the Grid Service

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Performance of hard real-time transaction scheduling policies in parallel database systems

Performance of hard real-time transaction scheduling policie...

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International Symposium on Modeling, Analysis and Simulation of computer and Telecommunication Systems (MASCOTS)

作者： S. Takkar S.P. Dandamudi Centre for Parallel and Distributed Computing School of Computer Science Carleton University Ottawa ONT Canada

Real-time transactions, in addition to preserving consistency of the database as in traditional transactions, have to meet the deadlines. Scheduling real-time transactions in parallel database systems has not received much attention. This paper focuses on real-time transaction scheduling in shared-nothing parallel database systems. We evaluate the performance of a new priority-based scheduling policy, in which all scheduling decisions are made locally by each node. In contrast, several other algorithms, proposed for the distributed systems, require communication among the nodes to globally synchronize their local block and abort decisions. Such synchronization can deteriorate performance as real-time transactions will have to meet deadlines. We use miss ratio as the performance metric and show that, in general, the new policy provides a superior performance for the workload and system parameters considered in this study.

关键词： Real time systems Database systems Transaction databases Processor scheduling System recovery Timing distributed computing computer science distributed databases Measurement

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An approach to support a single service provider address image for wide area networks environment

An approach to support a single service provider address ima...

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International Conference on parallel computing in Electrical Engineering (PARLEC)

作者： J.H. Abawajy Centre for Parallel and Distributed Computing School of Computer Science Carleton University Ottawa ONT Canada

Request dispatching mechanism is at the heart of any cluster-computing environment. The goal is to support a single service provider address image for a given cluster of workstations. That is to say a given cluster publicises a single IP address and client requests are addressed to that IP address. This means, from the client's viewpoint, there are no nodes in the cluster, only services and the network names through which they are accessible. As a result, the cluster becomes a single virtual node. We propose a simple and elegant scheme for making the cluster transparent to clients outside the cluster such that the clients can interact with the cluster as if it were a single high-performance and highly available resource.

关键词： Wide area networks Workstations computer architecture Network servers Dispatching Local area networks distributed computing computer science Heart Buildings

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Performance evaluation of nested-loop join processing on networks of workstations

Performance evaluation of nested-loop join processing on net...

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International Conference on parallel and distributed Systems (ICPADS)

作者： K. Imasaki S. Dandamudi Centre for Parallel and Distributed Computing School of Computer Science Carleton University Ottawa ONT Canada

Networks of workstations (NOWs) are attractive for parallel processing due to their cost advantage. This paper investigates the performance issues in processing join operations and the inherent tradeoff in the networked workstation environment. Specifically, we look at the performance of the nested-loop join algorithm. Since NOWs are heterogeneous in nature, load sharing is important for their performance. We evaluated the performance of three load sharing methods: static equal, static proportional and dynamic scheduling with fixed-chunk size. The three scheduling methods are evaluated on an experimental heterogeneous network of workstations with non-query background loads. Our experimental result suggest that, when there is no background load, dynamic scheduling outperforms static equal scheduling (up to 40%) and marginally better (about 10% better speedup) than the static proportional scheduling. When there is dynamic background load on nodes, dynamic scheduling provides substantial performance improvement over the static proportional scheduling (up to 50%) and static equal scheduling (up to about 100%). In all cases, selection of an appropriate chunk size is important in dynamic scheduling.

关键词： Workstations Dynamic scheduling Concurrent computing Databases parallel processing Master-slave Processor scheduling Application software Throughput distributed computing

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Time/space sharing distributed job scheduling policy in a workstation cluster environment

Time/space sharing distributed job scheduling policy in a wo...

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International Conference on parallel computing in Electrical Engineering (PARLEC)

作者： J.H. Abawajy S.P. Dandamudi Centre for Parallel and Distributed Computing School of Computer Science Carleton University Ottawa ONT Canada

This paper presents an algorithm for scheduling communication-intensive parallel applications in workstation clusters environment. The proposed scheduling policy combines the best attributes of both space-sharing and time-sharing principles and coexists with local schedulers (e.g., the Windows NT scheduler), which both provides coordinated scheduling and can generalise to provide a wide range of resource abstractions.

关键词： Workstations Processor scheduling Time sharing computer systems Operating systems distributed computing Delay computer science Clustering algorithms Scheduling algorithm Application software

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distributed hierarchical workstation cluster co-ordination scheme

Distributed hierarchical workstation cluster co-ordination s...

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International Conference on parallel computing in Electrical Engineering (PARLEC)

作者： J.H. Abawajy S.P. Dandamudi Centre for Parallel and Distributed Computing School of Computer Science Carleton University Ottawa ONT Canada

When a set of geographically distributed autonomous clusters of workstations are combined into a single large-scale virtual distributed system, a control mechanism for coordinating the activities of the combined system for effective utilisation of the resources is indispensable. This paper presents a co-ordination mechanism suitable for scheduling and distributing services across the host of such large-scale virtual distributed systems. The proposed scheme is scalable and reliable. Also, it combines both centralised and decentralised co-ordination mechanisms while eliminating/minimising their drawbacks.

关键词： Workstations Scheduling Resource management Large-scale systems distributed control Control systems Local area networks Wide area networks distributed computing computer science

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Grid computing in China

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Journal of Grid computing 2004年第2期2卷 193-206页

作者： Yang, Guangwen Jin, Hai Li, Minglu Xiao, Nong Li, Wei Wu, Zhaohui Wu, Yongwei Tang, Feilong Department of Computer Science and Technology Tsinghua University Beijing China School of Computer Huazhong University of Science and Technology Wuhan China Department of Computer Science and Engineering Shanghai Jiao Tong University Shanghai China Key Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha China Institute of Computing Technology Chinese Academy of Sciences Beijing 100080 China College of Computer Science Zhejiang University Hangzhou 310027 China

Grid computing presents a new trend to distributed computation and Internet applications, which can construct a virtual single image of heterogeneous resources, provide uniform application interface and integrate widespread computational resources into super, ubiquitous and transparent aggregation. In the adoption of Grid computing, China, who is facing more resource heterogeneity and other specific demands, has put much effort on both research and practical utilization. In this paper, we introduce the major China Grid research projects and their perspective applications. First we give the overview of the four government-sponsored programs in Grid, namely the China National Grid, ChinaGrid, NSFC Grid, and ShanghaiGrid. Then we present six representative ongoing Grid systems in details, which are categorized into Grid middleware and Grid application. This paper provides the general picture of Grid computing in China, and shows the great efforts, devotion and confidence in China to use Grid technology to boost the society, economics and scientific research. © Springer 2004.

关键词： Grid computing

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