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2011 IEEE 3rd International Conference on Communication Software and Networks, ICCSN 2011

作者： Bin, Huang Yu-Xing, Peng School of Computer Science Wuhan University Wuhan China National Laboratory of Parallel and Distributed Processing School of Computer Science National University of Defense Technology Changsha China

ISBN: (纸本)9781612844855

A Cloud may be seen as a type of flexible computing infrastructure consisting of many compute nodes, where resizable computing capacities can be provided to different customers. To fully harness the power of the Cloud, efficient data management is needed to handle huge volumes of data and support a large number of concurrent end users. To achieve that, a scalable and high-throughput indexing scheme is generally required. Such an indexing scheme must support parallel search to improve scalability. In this paper, we present a bitmap based indexing scheme for efficient data processing in the Cloud. Our approach can be summarized as follows. First, we build a local bitmap index for each compute node which only indexes data residing on the node. Second, we organize the compute nodes as a structured overlay and each node maintains a portion of the global index for the whole different data. The global index is also bitmap index to indicate the node each data resides in. Third, all bitmaps are compressed by adopting run-length coding for reducing storage requirement. We conduct extensive experiments on a LAN, and the results demonstrate that our indexing scheme is dynamic, efficient and scalable. © 2011 IEEE.

关键词： Information management

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A construction technique of constant degree P2P systems towards efficient complex queries

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Jisuanji Yanjiu yu Fazhan/Computer Research and Development 2011年第3期48卷 374-381页

作者： Wang, Xiaohai Peng, Yuxing Li, Dongsheng Key Laboratory of Science and Technology for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

Constant degree peer-to-peer (P2P) system is turning into the P2P domain's promising hotspot due to constant degree digraphs having good propertis. However, it is often hard to convert a stardard constant degree digraph to a DHT schema. Thus, most researches focus on DHT's construction and maintenance, while leaving optimization and supporting to complex query behind. Underlying topology affects upper-layers' character a lot. For constant degree P2P topologies, their inherent property makes a constant degree P2P system built using classical technique be poor in the data locality, and unfit for efficient, low-cost complex queries. Aiming at this shortage, a general-purpose construction technique towards efficient complex queries is proposed, which adds an embedding transformation layer between data layer and DHT overlay. In this way, adjacent data are stored in overlay's adjacent peers and the data locality is improved, so that the number of peers referred in complex queries can be minimized with a limited time overhead. To validate this technology, the first constant degree P2P system based on Kautz digraph FissionE is reconstructed as a typical example, which includes re-allocating of resources, query algorithm and locality maintenance strategies. Experimental results show that this construction technique can ensure data locality, reduce query cost and lead to systems' efficiency without changing the underlying DHT layer.

关键词： Peer to peer networks

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Toward optimal deployment of communication-intensive cloud applications

Toward optimal deployment of communication-intensive cloud a...

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International Conference on Cloud Computing

作者： Fan, Pei Wang, Ji Zheng, Zibin Lyu, Michael R. National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China Dept. of Computer Science and Engineering Chinese University of Hong Kong Hong Kong Hong Kong

ISBN: (纸本)9780769544601

Strongly promoted by the leading industrial companies, cloud computing becomes increasingly popular in recent years. The growth rate of cloud computing surpasses even the most optimistic predictions. A cloud application is a large-scale distributed system that consist a lot of distributed cloud nodes. How to make optimal deployment of cloud applications is a challenging research problem. When deploying a cloud application to the cloud environment, cloud node ranking is one of the most important approaches for selecting optimal cloud nodes for the cloud application. Traditional ranking methods usually rank the cloud nodes based on their QoS values, without considering the communication performance between cloud nodes. However, such kind of node relationship is very important for the communication-intensive cloud applications (e.g., Message Passing Interface (MPI) programs), which have a lot of communications between the selected cloud nodes. In this paper, we propose a novel clustering-based method for selecting optimal cloud nodes for deploying communication-intensive applications to the cloud environment. Our method not only takes into account the cloud node qualities, but also the communication performance between different nodes. We deploy several well-known MPI programs on a real-world cloud and compare our method with other methods. The experimental results show the effectiveness of our cluster-based method. © 2011 IEEE.

关键词： Quality of service

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A causality based dynamic message ordering for DVEs on Wide Area Network

A causality based dynamic message ordering for DVEs on Wide ...

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IEEE International Conference on Communication Software and Networks

作者： Zhou, Hangjun Fu, Sha Department of Information Management Hunan University of Finance and Economics Chang Sha Hu Nan China Key Laboratory of Science and Technology for National Defence of Parallel and Distributed Processing School of Computer Science National University of Defense Technology Chang Sha Hu Nan China

ISBN: (纸本)9781612844855

Due to the large message transmission latency in distributed Virtual Environments(DVEs) on Wide Area Net-work(WAN), the effectiveness of causality consistency control of message ordering is determined by not only causal order of messages but also the real-timeness. If merely causal order is considered, the real-time property of DVEs may not be ensured because of the unlimited waiting time for the delayed messages. While if only real-timeness is emphasized, there may be too many delayed messages, which have to be discarded, to maintain the quality of causal message ordering. Therefore, a trade-off between the quality of causal order delivery and real-timeness is necessary for DVEs. In this article, a novel causality based message ordering approach is presented. In general, this new approach dynamically balances the demands of causal order delivery and real-timeness. Experiment results demonstrate the approach can enhance the quality of causality, while simultaneously keep the real-time property of DVEs. © 2011 IEEE.

关键词： Wide area networks

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An effective control scheme to ensure real-time causal order in large-scale distributed interactive simulations

An effective control scheme to ensure real-time causal order...

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2011 IEEE 3rd International Conference on Communication Software and Networks, ICCSN 2011

ISBN: (纸本)9781612844855

When a large-scale distributed interactive simulation system is running on WAN, the sites usually disperse over a wide area in geography, which results in the simulation clock of each site is hardly to be accurately synchronized with that of other sites. The asynchronous clocks and large transmission latency on WAN bring on a problem for the large-scale simulations to preserve the real-time causal order delivery of received events at each site. In this article, we analyze the indirect way to compare the values of asynchronous simulation clocks at first, and then propose a novel scheme which can select the reconstructible causal control information for each message so as to ensure the causal ordering of events in real time. Experiments demonstrate that the scheme can weaken the effect of network latency, reduce the overhead of the transmission amount of control information and improve the causal order consistency in asynchronous distributed simulations. © 2011 IEEE.

关键词： Real time control

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A multi-layered emulation platform to verify the effectiveness of consistency control approaches about message ordering

A multi-layered emulation platform to verify the effectivene...

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IEEE International Conference on Communication Software and Networks

ISBN: (纸本)9781612844855

It is an important issue to preserve the consistent delivering order of messages at each site in distributed Virtual Environments(DVEs). Currently, the violations of message delivery order are inclined to happen in the large-scale and frequently interactive DVEs running on Wide Area Network(WAN). The inconsistent anomalies are characterized as unpredictable, unrepeatable and uncontrollable, which results in the severe problem for the development of the consistency control approaches. Meanwhile, it is also highly expensive to directly verify the proposed approaches on WAN. Therefore, in this paper, we design and establish an original multi-layered emulation platform in LAN, which can emulate the network latency of WAN and repeat the scenarios of violations. On the platform, the designers of consistency approaches don't have to spend efforts to realize the fundamental functions of the verification, but could pay more attention to the development and optimization of the control algorithms, which is very beneficial for the improvement of message ordering approaches. © 2011 IEEE.

关键词： Wide area networks

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Power Optimization for GPU Programs Based on Software Prefetching

Power Optimization for GPU Programs Based on Software Prefet...

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IEEE International Conference on Trust, Security and Privacy in Computing and Communications (TrustCom)

作者： Yisong Lin Tao Tang Guibin Wang Key Laboratory of Science and Technology for National Defence of Parallel and Distributed Processing National University of Defense and Technology Changsha China

GPUs render higher computing unit density than contemporary CPUs and thus exhibit much higher power consumption despite its higher power efficiency. The power consumption has become an important issue that impacts CPU's applications, thereby necessitating the low power optimization technology for GPUs. Software prefetching is an efficient way to alleviate the memory wall problem which overlaps the computing and memory access latencies. However, software prefetching will cause some power overhead because it increases the number and density of the instructions. Thus, we should consider the balance between the performance income and the power overhead when applying the optimization. To address this problem, in this paper we first analyze the multi-thread execution model of GPU and validate the potential space of software prefetching optimization. Then we give the software prefetching method for GPU programs to improve the performance. Aiming at two different objects: energy optimization under performance constraint and performance optimization under power constraint, we discuss the optimization methods based on software prefetching and dynamic voltage scaling technologies. The experimental results show that our method can efficiently optimize the energy consumption (performance) under the performance (power) constraint.

关键词： Prefetching Graphics processing unit Optimization Power demand Registers

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A skew angle detection algorithm based on maximum gradient difference

A skew angle detection algorithm based on maximum gradient d...

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2011 International Conference on Transportation, Mechanical, and Electrical Engineering, TMEE 2011

作者： Wang, Dan Wang, Xichang Liu, Jiang Institute of Information Science and Engineering Shandong Normal University Shandong Province Key Laboratory for Distributed Computer Software Novel Technology Shandong China Shandong Oumasoft Co. Ltd Research Institute of Digital Image Processing Shandong China

ISBN: (纸本)9781457717017

In order to resolve the problem of skew phenomenon in the handwritten document image during the scanning process, a new skew angle detection algorithm based on maximum gradient difference as well as Hough transform was proposed in the paper. Firstly, text lines are labeled by using maximum gradient difference, and then we use the method of non-text filtering to get rid of shorter text lines and dots. Finally, margin information is extracted after refining on text lines, and two-stage Hough transform is made to the margin extracted information with the strategy varying from "coarse" to "fine" strategy, calculating the skew angle of document image which is fixed by the average of several longest lines. Experiment results shows that the algorithm detects skew angles of document image more rapidly and accurately than Hough transform alone. © 2011 IEEE.

关键词： Hough transforms

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Research on Online Failure Prediction Model and Status Pretreatment Method for Exascale System

Research on Online Failure Prediction Model and Status Pretr...

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International Conference on Cyber-Enabled distributed Computing and Knowledge Discovery, CyberC

作者： Hao Zhou Yanhuang Jiang National Laboratory of Parallel and Distributed Processing College of Computer Science National University of Defense Technology Changsha China

The reliability issue of Exascale system is extremely serious. Traditional passive fault-tolerant methods, such as rollback-recovery, can not fully guarantee system reliability any more because of their large executing overhead and long recovering duration. Active fault tolerance is expected to become another important fault-tolerant approach for Exascale system. Focusing on system failure prediction, which is one key step of active fault tolerance, we construct online failure prediction model and research on the effective method of system status pretreatment. In order to improve the accuracy and real-time feature of current methods, the proposed Improved Adaptive Semantic Filter (IASF) method processes the latest system logs regularly, filtering useless information out of them according to their semantics. Adopting the main idea of Vector Space Model (VSM), IASF method creates Event Vector corresponding to each log record. By calculating the cosine of vectorial angle, it evaluates the semantics correlation between different log records, and then executes temporal and spatial redundant filter considering the burst feature of log records. IASF method is insensitive to the type of system log and does not introduce any expert system or domain knowledge. The experiment result shows that system can eliminate about 99.6% of useless log records after executing IASF method.

关键词： Fault tolerance Fault tolerant systems Vectors Correlation Information filters Predictive models

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The prediction model based on RBF network in achieving elastic cloud

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Advances in Information sciences and Service sciences 2011年第11期3卷 67-78页

作者： Shi, Peichang Wang, Huaimin Ding, Bo Liu, Ran Wang, Tianzuo National Laboratory for Parallel and Distributed Processing School of Computer and Science National University of Defense Technology China Department of Electronics and Information Engineering Huazhong University of Science Technology China

Cloud needs to have rapid and elastic resources supply capability, because of the fluctuant resources demand of end-users. Multi-scale resources elastic binding is an important method to provide cloud services with rapid and elastic service capability. The most challenging problem in multi-scale resources elastic binding is how to predict the dynamic resource demand of end-users, and then decide when and to what extent multi-scale resources need elastic binding based on the prediction. In this paper, we present the prediction model based on RBF (Radial Basis Function) Network, which is used to predict end-users resource demand in advance. Compared with current prediction methods, it has faster prediction speed and higher prediction accuracy. Then we use traces data (the bandwidth demand of Web type of cloud services) collected from a real-world cloud provider: ChinaCache, as the training and testing data set to validate the method. Finally, we evaluate the predicted results using general prediction accuracy metrics. The results prove that the prediction model based on RBF network is able to resolve the decision problem in multi-scale resources elastic binding.

关键词： Radial basis function networks

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