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Proceedings of the 20th international conference companion on World wide web

作者： Tang, Jintao Wang, Ting Wang, Ji Lu, Qin Li, Wenjie School of Computer National University of Defense Technology Changsha China Department of Computing Hong Kong Polytechnic University Hong Kong Hong Kong National Laboratory for Parallel and Distributed Processing Changsha China

ISBN: (纸本)9781450305181

Applying graph clustering algorithms in real world networks needs to overcome two main challenges: the lack of prior knowledge and the scalability issue. This paper proposes a novel method based on the topological features of complex networks to optimize the clustering algorithms in real-world networks. More specifically, the features are used for parameter estimation and performance optimization. The proposed method is evaluated on real-world networks extracted from the web. Experimental results show improvement both in terms of Adjusted Rand index values as well as runtime efficiency. © 2011 Authors.

关键词： Parameter estimation

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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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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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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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Storage allocation for redundancy scheme in reliability-aware cloud systems

Storage allocation for redundancy scheme in reliability-awar...

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International Conference on Communication Software and Networks, ICCSN

作者： Zhen Huang Yuan Yuan Yuxing Peng National Laboratory of Parallel and Distributed Processing Computer Department National University of Defense Technology Changsha China

As the burst increasing of created and demand on information and data, the efficient solution on storage management is highly required in the cloud storage systems. As an important component of management, storage allocation scheme aims to use a low redundancy and also to achieve a high reliability. However, the two aims are hard to be unified. Considering the practical situation of Cloud systems, we propose a systematic storage allocation scheme to touch them both. And we also study the impact of many factors to the data reliability.

关键词： Irrigation Chaos Redundancy

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Semantic web service composition using answer set planning

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International Journal of Advancements in Computing technology 2011年第5期3卷 20-31页

作者： Qian, Jun-Yan Huang, Guo-Wang Zhao, Ling-Zhong National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China Department of Computer science and engineering Guilin University of Electronic Technology Guilin 541004 China

This paper presents a method that adapting planning description to bring the semantic information into play for service composition through action language C. It shows how service descriptions can be expressed by preconditions and effects and the action language C provides a richer syntax and semantic for complex service descriptions. We also presents the algorithm of Translating semantic Web service described by OWL-S to action language C. Thanks to the structured description and the powerful expression of C, we only consider the initial Situation and the desired goal ignoring details of transition and planning. At last we use satisfiability planning to solve the planning problem by translating the action language into disjunctive logic program.

关键词： Web services

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Modeling and Analysis of Sharing Ratio Enforcement in Private BitTorrent Communities

Modeling and Analysis of Sharing Ratio Enforcement in Privat...

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IEEE International Conference on Communications (ICC)

作者： Adele L. Jia Lucia D'Acunto Michel Meulpolder Johan A. Pouwelse Parallel and Distributed Systems Group Department of Computer Science Delft University of Technology Netherlands

Providing incentives for user contribution has been one of the primary design goals of Peer-to-Peer systems. The newly-emerged BitTorrent private communities adopt Sharing Ratio Enforcement (SRE) on top of BitTorrent's incentive mechanism, Tit-For-Tat, in order to strictly enforce a minimum contribution a member has to provide, in relation to the amount of service it has received. In this paper, we provide a theoretical model to analyze 1) how SRE provides seeding incentives, and 2) how SRE influences the download performance in the system. Specifically, we study the influence of the SRE threshold (i.e., the minimum sharing ratio requirement) and the bandwidth heterogeneity of the peers in the system. In our analysis, we assume users to be rational, i.e., peers seed only the minimum amount required by SRE, and we show that the download performance as predicted by our model represents a lower bound for the actual performance that can be reached in a BitTorrent private community. Hence, following our model, community administrators can predict the minimum performance level their systems will be able to reach.

关键词： Thin film transistors Communities Analytical models Bandwidth Peer to peer computing Mathematical model Steady-state

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Fast download but eternal seeding: The reward and punishment of Sharing Ratio Enforcement

Fast download but eternal seeding: The reward and punishment...

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International Conference on Peer-to-Peer Computing

作者： Adele L. Jia Rameez Rahman Tamás Vinkó Johan A. Pouwelse Dick H.J. Epema Parallel and Distributed Systems Group Department of Computer Science Delft University of Technology Netherlands

Many private BitTorrent communities employ Sharing Ratio Enforcement (SRE) schemes to incentivize users to contribute their upload resources. It has been demonstrated that communities that use SRE are greatly oversupplied, i.e., they have much higher seeder-to-leecher ratios than communities in which SRE is not employed. The first order effect of oversupply under SRE is a positive increase in the average downloading speed. However, users are forced to seed for extremely long times to maintain adequate sharing ratios to be able to start new downloads. In this paper, we propose a fluid model to study the effects of oversupply under SRE, which predicts the average downloading speed, the average seeding time, and the average upload capacity utilization for users in communities that employ SRE. We notice that the phenomenon of oversupply has two undesired negative effects: a) Peers are forced to seed for long times, even though their seeding efforts are often not very productive (in terms of low upload capacity utilization); and b) SRE discriminates against peers with low bandwidth capacities and forces them to seed for longer durations than peers with high capacities. To alleviate these problems, we propose four different strategies for SRE, which have been inspired by ideas in social sciences and economics. We evaluate these strategies through simulations. Our results indicate that these new strategies release users from needlessly long seeding durations, while also being fair towards peers with low capacities and maintaining high system-wide downloading speeds.

关键词： Communities Steady-state Peer to peer computing Bandwidth IEEE Communications Society Analytical models Thin film transistors

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Context-Aware Scheduling in Wireless Networks with Successive Interference Cancellation

Context-Aware Scheduling in Wireless Networks with Successiv...

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IEEE International Conference on Communications Workshops

作者： Shaohe Lv Weihua Zhuang Xiaodong Wang Xingming Zhou National Laboratory of Parallel and Distributed Processing National University of Defense Technology Department of Electrical and Computer Engineering University of Waterloo

ISBN: (纸本)9781612842325

We consider the greedy scheduling based on the physical model in wireless networks with successive interference cancellation (SIC). There are two major stages in a scheduling scheme, link selection (to decide which link is scheduled next) and time slot selection (to deciding which slot is allocated to a given link). Most available schemes take a first-fit policy in the latter and strive to achieve good performance by careful selection of link ordering with respect to interference. Due to the accumulation effect and sequential detection nature of SIC, however, it is difficult to evaluate the interference of a link. As a result, many existing scheduling schemes become less efficient. In this paper, we take a new look on the problem and focus to the time slot selection stage. We define tolerance margin to measure the saturation of a link set and present two heuristic policies: one is to schedule a link to a slot such that the resulting set of links has a maximum tolerance margin;the other is to choose a slot such that the increase of tolerance margin is minimum. Simulation results show that the performance of the proposed schemes is better than the first-fit policy and is close to the optimal solution.

关键词： Link scheduling Successive interference cancellation Physical interference model

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The dynamic allocation model for the resources of cloud services delivery networks

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Jisuanji Xuebao/Chinese Journal of Computers 2011年第12期34卷 2305-2318页

作者： Shi, Pei-Chang Wang, Huai-Min Yin, Gang Liu, Xue-Ning Yuan, Xiao-Qun Shi, Dian-Xi National Laboratory for Parallel and Distributed Processing School of Computer and Science National University of Defense Technology Changsha 410073 China Department of Computer Science and Technology Tsinghua University Beijing 100084 China Department of Electronics and Information Engineering Huazhong Univ. of Sci. and Technol. Wuhan 430074 China

Cloud Services Delivery Networks (CSDN) constructs a layer distributed server overlay over the Internet, which uses the way to the nearest and on-demand approach providing services to end users. Facing the scale and diversification of the resource demand characteristics of the Internet cloud services, CSDN forms different logical sub-server overlay for different kinds of cloud services. However, most servers and bandwidth resources of CSDN are used to deliver the streaming and downloading kind of cloud services, and the dynamic allocation of their delivery resource is the main research emphasis in this paper. This paper first models the problem to be a multi-dimensional facility location problem, according to the two characteristics: the memory resource and bandwidth resource of this kind of application are the bottleneck resource;the hot contents of this kind of application can be delivered using the Peer-to-Peer mechanisms. After the model analyzed and its NP-Complete proved, we then propose a heuristic algorithm. Finally, using the service delivery cost savings as the performance metrics, while the actual system's operation trace is as the input, the effectiveness of the algorithm are comprehensively assessed.

关键词： Heuristic algorithms

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