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作者： Wang, Guibin National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha Hunan China

ISBN: (纸本)9783981080179

Although general purpose GPUs have relatively high computing capacity, they also introduce high power consumption compared with general purpose CPUs. Therefore low-power techniques targeted for GPUs will be one of the most hot topics in the future. On the other hand, in several application domains, users are unwilling to sacrifice performance to save power. In this paper, we propose an effective kernel fusion method to reduce the power consumption for GPUs without performance loss. Different from executing multiple kernels serially, the proposed method fuses several kernels into one larger kernel. Owing to the fact that most consecutive kernels in an application have data dependency and could not be fused directly, we split large kernel into multiple slices with strip-mining method, then fuse independent sliced kernels into one kernel. Based on the CUDA programming model, we propose three different kernel fusion implementations, with each one targeting for a special case. Based on the different strip-ming methods, we also propose two fusion mechanisms, which are called invariant-slice fusion and variant-slice fusion. The latter one could be better adapted to the requirements of the kernels to be fused. The experimental results validate that the proposed kernel fusion method could effectively reduce the power consumption for GPU. © 2011 EDAA.

关键词： Electric power utilization

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An ordering-based approach to the evaluation of trust systems

An ordering-based approach to the evaluation of trust system...

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IEEE International Conference on Communication Software and Networks

作者： Liu, Wei Tang, Yang-Bin Wang, Huai-Min Lu, Gang School of Computer National Univ. of Defense Technology Changsha Hunan China National Laboratory for Parallel and Distributed Processing Changsha Hunan China

ISBN: (纸本)9781612844855

Trust systems provide a promising way to build trust relationships among users in distributed and opening systems. However, it is difficult to make quantitatively comparative analysis on different trust systems because of the different application settings and the lack of effective measures. This paper constructs a framework of trust systems in terms of linear algebra, which helps us model and implement different systems in a uniform way. Besides, we propose an ordering-based approach to evaluating trust systems, then give two relevant ordering-base measures. The experiment results suggests that our method provides an effective way to analyze and evaluate trust systems. © 2011 IEEE.

关键词： Linear algebra

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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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Reducing repair traffic in P2P backup systems: Exact regenerating codes on hierarchical codes

Reducing repair traffic in P2P backup systems: Exact regener...

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作者： Huang, Zhen Biersack, Ernst Peng, Yuxing Department of Computer National Laboratory of Parallel and Distributed Processing National University of Defense Technology Changsha Hunan 410073 China Eurecom Sophia Antipolis France

Peer to peer backup systems store data on "unreliable" peers that can leave the system at any moment. In this case, the only way to assure durability of the data is to add redundancy using either replication or erasure codes. Erasure codes are able to provide the same reliability as replication requiring much less storage space. Erasure coding breaks the data into blocks that are encoded and then stored on different nodes. However, when storage nodes permanently abandon the system, new redundant blocks must be created, which is referred to as repair. For "classical" erasure codes, generating a new block requires the transmission of k blocks over the network, resulting in a high repair traffic. Recently, two new classes of erasure codes, Regenerating Codes and Hierarchical Codes, have been proposed that significantly reduce the repair traffic. Regenerating Codes reduce the amount of data uploaded by each peer involved in the repair, while Hierarchical Codes reduce the number of nodes participating in the repair. In this article we propose to combine these two codes to devise a new class of erasure codes called ER-Hierarchical Codes that combine the advantages of both. © 2011 ACM.

关键词： Repair

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Performance problems online detection in cloud computing systems via analyzing request execution paths

Performance problems online detection in cloud computing sys...

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Workshop on Proactive Failure Avoidance, Recovery, and Maintenance

作者： Mi, Haibo Wang, Huaimin Yin, Gang Cai, Hua Zhou, Qi Sun, Tingtao National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha China Computing Platform Alibaba Cloud Computing Company Hangzhou China

ISBN: (纸本)9781457703751

It is quite a headache for developers to online detect performance problems in large-scale cloud computing systems. The behavior and the hidden connections among the huge amount of runtime request execution paths in cloud computing systems usually contain useful information for performance problem detection. In this paper, we propose an approach to rapidly diagnose the source of performance degradation in large-scale non-stop cloud computing systems. The approach first groups the user requests into categories with a fast clustering algorithm;then applies the principal components analysis to extract the primary methods;finally compares the normal and abnormal behaviors of the primary methods to localize the main cause of performance problems. We conduct extensive experiments over a real-world enterprise system providing services for the public. The results show that our approach can locate the prime causes of performance problems accurately and efficiently.1 © 2011 IEEE.

关键词： Cloud computing

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Identifying faults in large-scale distributed systems by filtering noisy error logs

Identifying faults in large-scale distributed systems by fil...

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Workshop on Proactive Failure Avoidance, Recovery, and Maintenance

作者： Rao, Xiang Wang, Huaimin Shi, Dianxi Chen, Zhenbang Cai, Hua Zhou, Qi Sun, Tingtao National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China Computing Platform Alibaba Cloud Computing Corporation Hangzhou China

ISBN: (纸本)9781457703751

Extracting fault features with the error logs of fault injection tests has been widely studied in the area of large scale distributed systems for decades. However, the process of extracting features is severely affected by a large amount of noisy logs. While the existing work tries to solve the problem by compressing logs in temporal and spatial views or removing the semantic redundancy between logs, they fail to consider the co-existence of other noisy faults that generate error logs instead of injected faults, for example, random hardware faults, unexpected bugs of softwares, system configuration faults or the error rank of a log severity. During a fault feature extraction process, those noisy faults generate error logs that are not related to a target fault, and will strongly mislead the resulted fault features. We call an error log that is not related to a target fault a noisy error log. To filter out noisy error logs, we present a similarity-based error log filtering method SBF, which consists of three integrated steps: (1) model error logs into time series and use haar wavelet transform to get the approximate time series;(2) divide the approximate time series into sub time series by valleys;(3) identify noisy error logs by comparing the similarity between the sub time series of target error logs and the template of noisy error logs. We apply our log filtering method in an enterprise cloud system and show its effectiveness. Compared with the existing work, we successfully filter out noisy error logs and increase the precision and the recall rate of fault feature extraction.1 © 2011 IEEE.

关键词： Errors

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不确定Skyline查询技术研究

不确定Skyline查询技术研究

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第29届中国数据库学术会议

作者： Wang Yijie 王意洁 Li Xiaoyong 李小勇 Yang Yongtao 杨永滔 Qi Yafei 祁亚斐 Wang Guangdong 王广东 National Key Laboratory for Parallel and Distributed Processing College of Computer National Unive 国防科学技术大学计算机学院并行与分布处理国家重点实验室长沙 410073

当前不确定数据广泛存在于诸如传感器网络、RFID网络、基于位置服务、移动对象管理网上购物和市场监控等各种实际应用中。不确定Skyline查询作为不确定数据管理的一个重要方面，由于其在决策制定、市场分析、环境监控和数据挖掘等方面... 详细信息

当前不确定数据广泛存在于诸如传感器网络、RFID网络、基于位置服务、移动对象管理网上购物和市场监控等各种实际应用中。不确定Skyline查询作为不确定数据管理的一个重要方面，由于其在决策制定、市场分析、环境监控和数据挖掘等方面的重要作用，近年来在数据库和网络计算领域受到广泛关注。首先，概述了各种不确定数据类型上的Skyline查询定义，包括离散、连续概率分布模型以及不完全数据上的Skyline查询定义;其次，分析了不确定Skyline查询的特点，并在此基础上综述了现有的各种不确定数据集上的集中式和分布式Skyline查询方法，重点分析了各种算法的原理和优缺点;再次，介绍了不确定数据流上的Skyline查询定义并综述了各种不确定数据流上的Skyline查询方法;最后，基于最新研究动态指出了未来不确定Skyline查询研究的趋势。

关键词：数据查询不确定数据分布式技术

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基于移动云计算的大规模上下文流处理框架研究

基于移动云计算的大规模上下文流处理框架研究

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第九届中国通信学会学术年会

作者： XIAO You 肖友 SHI Dian-xi 史殿习 National Key Laboratory for Parallel and Distributed Processing School of Computer ScienceNational 国防科技大学计算机学院并行与分布处理国家重点实验室长沙410073

随着移动云计算的兴起，有关于大规模移动设备上下文信息处理的研究成为了热点。目前比较流行的解决方案是采用基于MapReduce计算模型的Hadoop框架，它虽能解决大规模数据处理的吞吐量问题但是却不能很好的解决数据处理的时效问题。因... 详细信息

随着移动云计算的兴起，有关于大规模移动设备上下文信息处理的研究成为了热点。目前比较流行的解决方案是采用基于MapReduce计算模型的Hadoop框架，它虽能解决大规模数据处理的吞吐量问题但是却不能很好的解决数据处理的时效问题。因此，本文针对存在的问题，提出了移动云计算与流处理技术相结合的解决方案，并构建与实现了一个实时处理大规模上下文的流处理框架。最后通过此框架对本文的研究内容进行了验证，且以一个道路实况监测的实例验证了框架的可行性及有效性。

关键词：移动云计算上下文信息流处理框架可行性分析

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An efficient two-level bitmap index for cloud data management

An efficient two-level bitmap index for cloud data managemen...

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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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基于物理轨迹数据和社会网络的泛化行程推荐

基于物理轨迹数据和社会网络的泛化行程推荐

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第六届中国传感器网络学术会议(CWSN 2012)

作者： MENG Xiang-Xu 孟祥旭 WANG Xiao-Dong 王晓东 ZHOU Xing-Ming 周兴铭 National Key Laboratory of Parallel and Distributed Processing(College of Computer Science National 并行与分布处理国家重点实验室(国防科学技术大学计算机学院) 湖南长沙410073

人类活动行程的制定往往基于宽泛的最初意向，通过综合考虑各种约束条件加以优化而完成。当前，基于位置点名称查找的行程制定方法，不支持用户一次性提交多个具有时序关系的宽泛出行意向，更不能同时为多个地理位置点提供详细的最优驾... 详细信息

人类活动行程的制定往往基于宽泛的最初意向，通过综合考虑各种约束条件加以优化而完成。当前，基于位置点名称查找的行程制定方法，不支持用户一次性提交多个具有时序关系的宽泛出行意向，更不能同时为多个地理位置点提供详细的最优驾车方案。基于位置社交网络信息和车辆历史轨迹数据，探索了支持用户多个模糊意向输入的泛化行程推荐框架，主要工作包括：(1)对泛化的行程推荐问题进行建模;(2)设计并实现了基于分类树的地理位置点(POI)查询策略和算法;(3)提出了基于Voronoi图的GPS轨迹分析模型，并实现了任意两个位置点间最优行驶路径计算方法;(4)联合社会网络和语义交通信息图，基于蚁群算法进行行程的推荐，并实现了原型系统。实验及问卷调查结果表明，推荐结果的用户满意度可达80％。

关键词：行程规划泛化模型优化设计物理轨迹数据社会网络

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