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International Conference on parallel and distributed Systems (ICPADS)

作者： Liufeng Wang Huaimin Wang Lu Cai Rui Chu Pengfei Zhang Lanzheng Liu National Key Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha China School of Economics and Management Xi'an University Xi'an China

Increasing Internet business and computing footprint motivate server consolidation in data centers. Through virtualization technology, server consolidation can reduce physical hosts and provide scalable services. However, the ineffective memory usage among multiple virtual machines (VMs) becomes the bottleneck in server consolidation environment. Because of inaccurate memory usage estimate and the lack of memory resource managements, there is much service performance degradation in data centers, even though they have occupied a large amount of memory. In order to improve this scenario, we first introduce VM's memory division view and VM's free memory division view. Based on them, we propose a hierarchal memory service mechanism. We have designed and implemented the corresponding memory scheduling algorithm to enhance memory efficiency and achieve service level agreement. The benchmark test results show that our implementation can save 30% physical memory with 1% to 5% performance degradation. Based on Xen virtualization platform and balloon driver technology, our works actually bring dramatic benefits to commercial cloud computing center which is providing more than 2,000 VMs' services to cloud computing users.

关键词： Memory management Resource management Servers Scheduling algorithm Benchmark testing Cloud computing System performance

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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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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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International Conference on Dependable Systems and Networks Workshops (DSN-W)

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

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.

关键词： Cloud computing Principal component analysis Instruments Degradation Servers Data mining Accuracy

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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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International Conference on Dependable Systems and Networks Workshops (DSN-W)

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

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.

关键词： Time series analysis Noise measurement Feature extraction Wavelet transforms Computer crashes Complexity theory Approximation methods

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Scheduling in wireless ad hoc networks with successive interference cancellation

Scheduling in wireless ad hoc networks with successive inter...

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IEEE Annual Joint Conference: INFOCOM, IEEE Computer and Communications Societies

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

ISBN: (纸本)9781424499199

Successive interference cancellation (SIC) is an effective way of multipacket reception (MPR) to combat interference in wireless networks. To understand the potential MPR advantages, we study link scheduling in an ad hoc network with SIC at the physical layer. The fact that the links detected sequentially by SIC are correlated at the receiver poses key technical challenges. We characterize the link dependence and propose simultaneity graph (SG) to capture the effect of SIC. Then interference number is defined to measure the interference of a link. We show that scheduling over SG is NP-hard and the maximum interference number bounds the performance of maximal greedy schemes. An independent set based greedy scheme is explored to efficiently construct a maximal feasible schedule. Moreover, with careful selection of link ordering, we present a scheduling scheme that improves the bound. The performance is evaluated by both simulations and measurements in testbed. The throughput gain is on average 40% and up to 120% over IEEE 802.11. The complexity of SG is comparable with that of conflict graph, especially when the network size is not large.

关键词： Interference Silicon carbide Receivers Schedules Protocols Wireless networks Scheduling

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Managing Data-Objects in Dynamically Reconfigurable Caches

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Journal of Computer Science & Technology 2010年第2期25卷 232-245页

作者：杨学军吴俊杰曾坤唐玉华 National Laboratory for Parallel and Distributed Processing School of ComputerNational University of Defense Technology

The widening gap between processor and memory speeds makes cache an important issue in the computer system design. Compared with work set of programs, cache resource is often rare. Therefore, it is very important for a computer system to use cache efficiently. Toward a dynamically reconfigurable cache proposed recently, DOOC （Data- Object Oriented Cache）, this paper proposes a quantitative framework for analyzing the cache requirement of data-objects, which includes cache capacity, block size, associativity and coherence protocol. And a kind of graph coloring algorithm dealing with the competition between data-objects in the DOOC is proposed as well. Finally, we apply our approaches to the compiler management of DOOC. We test our approaches on both a single-core platform and a four-core platform. Compared with the traditional caches, the DOOC in both platforms achieves an average reduction of 44.98% and 49.69% in miss rate respectively. And its performance is very close to the ideal optimal cache.

关键词： cache data-object data reuse data-object oriented cache （DOOC） graph coloring

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Hierarchical diagnostic approach for performance problems in cloud computing platforms

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Tongxin Xuebao/Journal on Communications 2011年第7期32卷 114-124页

作者： Mi, Hai-Bo Wang, Huai-Min Cai, Hua Yin, Gang Zhou, Qi Sun, Ting-Tao Zhou, Yang-Fan National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China Computing Platform Alibaba Cloud Computing Company Hangzhou 310023 China Shenzhen Research Institute Chinese Univ. of Hong Kong Shenzhen 518057 China

A hierarchical diagnosis approach, namely Magnifier, was proposed, which models the execution path graph of a user request as component layer, module layer and function layer, and detects anomalies from higher layer to lower layer separately. Extensive experiments were conducted on the Alibaba cloud computing platform. The results indicate that, under the conditions of large volume of data and high complexity of execution paths, Magnifier can accurately and efficiently locate the prime causes of performance degradation.

关键词： Cloud computing

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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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International Conference on Communication Software and Networks, ICCSN

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

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.

关键词： TV

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CoCache:云计算环境下虚拟磁盘的协作式持久缓存

CoCache:云计算环境下虚拟磁盘的协作式持久缓存

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2012全国高性能计算学术年会

作者： LI Zi-Yang 李紫阳 ZHANG Zhao-Ning 张钊宁 PENG Yu-Xing 彭宇行 LI Hui-Ba 李慧霸 LIU Liu 刘流 National Laboratory for Parallel and Distributed Processing National University of Defense Technolo 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湖南长沙 410073 PLA Troops 95937 Units 77 123100 中国人民解放军95937 部队77分队 123100

分析了云计算环境中虚拟机映像存储系统所面临的问题和挑战,设计并实现了一种系统层的虚拟磁盘协作式持久缓存CoCache,能够充分利用各个节点缓存的服务能力,使其暂存的虚拟机映像数据能够为其他节点提供读取服务.CoCache 实现了物理节点... 详细信息

分析了云计算环境中虚拟机映像存储系统所面临的问题和挑战,设计并实现了一种系统层的虚拟磁盘协作式持久缓存CoCache,能够充分利用各个节点缓存的服务能力,使其暂存的虚拟机映像数据能够为其他节点提供读取服务.CoCache 实现了物理节点间P2P 模式数据传输,达到了扩展存储系统数据服务能力的目的.CoCache 实现层次位于Linux 内核态,可以支持任何的VMM.实验结果显示该协作式持久缓存可以有效地减少虚拟机读取数据的传输开销,提升虚拟机存储系统的负载能力.

关键词：云计算虚拟机分布式存储协作式缓存

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Toward Optimal Deployment of Communication-Intensive Cloud Applications

Toward Optimal Deployment of Communication-Intensive Cloud A...

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IEEE International Conference on Cloud Computing, CLOUD

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

Strongly promoted by the leading industrial companies, cloud computing becomes increasingly popular in re-cent 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.

关键词： Time factors Cloud computing Benchmark testing Quality of service Servers Clustering algorithms Databases

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