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A coarse-grained reconfigurable computing architecture with loop self-pipelining

Science in China(Series F) 2009年第4期52卷 575-587页

作者： DOU Yong WU GuiMing XU dinHui ZHOU XingMing National Laboratory for Parallel & Distributed Processing National University of Defense Technology Changsha 410073 China

Reconfigurable computing tries to achieve the balance between high efficiency of custom computing and flexibility of general-purpose computing. This paper presents the implementation techniques in LEAP, a coarse-grained reconfigurable array, and proposes a speculative execution mechanism for dynamic loop scheduling with the goal of one iteration per cycle and implementation techniques to support decoupling synchronization between the token generator and the collector. This paper also in- troduces the techniques of exploiting both data dependences of intra- and inter-iteration, with the help of two instructions for special data reuses in the loop-carried dependences. The experimental results show that the number of memory accesses reaches on average 3% of an RISC processor simulator with no memory optimization. In a practical image matching application, LEAP architecture achieves about 34 times of speedup in execution cycles, compared with general-purpose processors.

关键词： reconfigurable computing loop pipelining data driven register promotion

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SKY:Efficient peer-to-peer networks based on distributed Kautz graphs

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Science in China(Series F) 2009年第4期52卷 588-601页

作者： ZHANG YiMing LU XiCheng LI DongSheng National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

Many proposed P2P networks are based on traditional interconnection topologies. Given a static topology, the maintenance mechanism for node join/departure is critical to designing an efficient P2P network. Kautz graphs have many good properties such as constant degree, low congestion and optimal diameter. Due to the complexity in topology maintenance, however, to date there have been no effective P2P networks that are proposed based on Kautz graphs with base ~ 2. To address this problem, this paper presents the ＂distributed Kautz （D-Kautz） graphs＂, which adapt Kautz graphs to the characteristics of P2P networks. Using the D-Kautz graphs we further propose SKY, the first effective P2P network based on Kautz graphs with arbitrary base. The effectiveness of SKY is demonstrated through analysis and simulations.

关键词： peer-to-peer network Kautz graph constant degree topology maintenance D-Kautz graph

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Mobility of internet-based virtual computing environment

Mobility of internet-based virtual computing environment

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15th International Conference on parallel and distributed Systems, ICPADS '09

作者： Shen, Siqi Wang, Ji Shen, Rui Zhang, Shengdong Fan, Pei National Laboratory for Parallel and Distributed Processing Changsha 410073 China

ISBN: (纸本)9780769539003

The Internet-based Virtual Computing Environment (iVCE) provides on-demand aggregation and autonomic collaboration mechanisms to facilitate the utilization of autonomous and dynamic Internet resources. Load balancing and fault tolerance are important issues when scheduling those transient resources. In this paper, we propose a mobility mechanism for the migration of various roles of agents in the iVCE platform. The mobility mechanism involves two parts of the iVCE platform: role container layer and event service layer. At the role container layer, a novel approach is proposed to handle the code and data mobility issue. At the event service layer, an efficient routing reconfiguration protocol is proposed based on a publish/subscribe system over DHTs to facilitate task migrations. Certain conditions must be satisfied before the migration of an agent to ensure the correctness of the whole process. Experiments are conducted to evaluate the performance of the mobility mechanism, and the experimental results show that it is suitable for implementing load balancing and fault tolerance in the iVCE. © 2009 IEEE.

关键词： Fault tolerance

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HyperSpring: Accurate and stable latency estimation in the hyperbolic space

HyperSpring: Accurate and stable latency estimation in the h...

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15th International Conference on parallel and distributed Systems, ICPADS '09

作者： Fu, Yongquan Wang, Yijie National Key Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology China

ISBN: (纸本)9780769539003

Predicting network latencies between Internet hosts can efficiently support large-scale Internet applications, e.g., file sharing service and the overlay construction. Several study use the Hyperbolic space to model the Internet densecore and many-tendril structure. However, existing Hyperbolic space based embedding approaches are not designed for accurate latency estimation in the distributed context. We present HyperSpring, which estimates latency by modelling a mass spring system in the Hyperbolic similar with Vivaldi. HyperSpring adopts coordinate initialization to speed up the convergence of coordinate computation, uses multiple-round symmetric updates to escape from bad local minima, and stabilizes coordinates by compensating RTT measurements to reduce the coordinate drifts. Evaluation results based on a network trace of 226 PlanetLab nodes indicate that, compared to Euclidean-space based Vivaldi, HyperSpring provides performance improvements for most nodes, and incurs slightly higher distortions for a small number of nodes. © 2009 IEEE.

关键词： Hyperbolic space Latency estimation Mass spring field

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iRank: Supporting proximity ranking for peer-to-peer applications

iRank: Supporting proximity ranking for peer-to-peer applica...

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15th International Conference on parallel and distributed Systems, ICPADS '09

作者： Fu, Yongquan Wang, Yijie National Key Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology China

ISBN: (纸本)9780769539003

Proximity ranking according to end-to-end network distances (e.g., Round-Trip Time, RTT) can reveal detailed proximity information, which is important in network management and performance diagnosis in distributed systems. However, to the best of our knowledge, there has been no similar work on this subject in the P2P computing field. We present a distributed rating method iRank, that enables proximity rankings by providing discrete ratings in a distributed manner. It formulates the proximity ranking as a rating problem that faithfully captures the proximity based on noisy distance measurements scalably and practically. The primary challenge in inferring proximity rankings is enforcing distributed ratings with complex rating policies. Our solution is based on reconstructing ratings by decomposing a centralized rating method Maximum Margin Matrix Factorization (MMMF) into independent sub-problems, that can be efficiently solved in a decentralized manner. By relaxing the dependence on infrastructure nodes that are a single point of failure and limit scalability, iRank can gracefully handle network churns. Through real network latency data sets, we demonstrate that iRank can predict ratings with low distortion, which are smaller than 20 percentage worse than the centralized method, in the context of synthetic complex rating policies. © 2009 IEEE.

关键词： Complex networks

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Anadem: A hybrid overlay network for content-based data distribution

Anadem: A hybrid overlay network for content-based data dist...

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15th International Conference on parallel and distributed Systems, ICPADS '09

作者： Zheng, Zhong Wang, Yi-Jie National Key Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha China

ISBN: (纸本)9780769539003

As an infrastructure for data distribution, overlay networks have to feature efficient routing and adequate robustness to achieve fast and accurate data distribution in the environment with node churn. Considering that the existing overlay networks mostly focus on single optimization objective and fail to ensure routing efficiency and robustness simultaneously, a hybrid overlay network for content-based data distribution - Anadem is proposed in this paper. Anadem achieves a better compromise between routing efficiency and robustness by combining the intercluster multiple structured topologies with the intra-cluster unstructured topologies. Anadem also provides mechanisms for dynamic concurrent cluster creation, cluster departure and load balance to make data distribution more adaptive to the dynamic network environment. Experimental results reveal that compared with existing overlay networks, Anadem can support fast and accurate content-based data distribution even when large amount of nodes fail in the system. © 2009 IEEE.

关键词： Overlay networks

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Jammer localization in wireless sensor networks

Jammer localization in wireless sensor networks

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5th International Conference on Wireless Communications, Networking and Mobile Computing, WiCOM 2009

作者： Yanqiang, Sun Xiaodong, Wang National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha China

ISBN: (纸本)9781424436934

Jamming style Denial-of-Service attack is the transmission of radio signals that disrupt communications by decreasing the signal to noise ratio. This kind of attack can be easily launched by jammer through either bypassing MAC-layer protocols or emitting a radio signal targeted at blocking a particular channel. In this paper, we consider the item of localizing a jammer in which little work has been done. First we explored the existing localization algorithms that have been used in wireless sensor networks. We then proposed a Geometry-Covering based Localization (GCL) algorithm, which utilizes the knowledge of computing geometry, especially the convex hull. Simulation results showed that GCL is able to achieve higher accuracy than Centroid Localization, and has the time complexity of O (nlogn) , which is proper to sensor networks. ©2009 IEEE.

关键词： Geometry

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Fine-grained parallel application specific computing for RNA secondary structure prediction using SCFGS on FPGA

Fine-grained parallel application specific computing for RNA...

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Embedded Systems Week 2009, ESWEEK 2009 - 2009 International Conference on Compilers, Architecture, and Synthesis for Embedded Systems, CASES'09

作者： Dou, Yong Xia, Fei Jiang, Jingfei National Laboratory for Parallel and Distributed Processing National University of Defence Technology 410073 ChangSha China

ISBN: (纸本)9781605586267

In the field of RNA secondary structure prediction, the CYK (Coche-Younger-Kasami) algorithm is a most popular methods using SCFG (stochastic context-free grammars) model. However, general purpose parallel computers including SMP multiprocessors or cluster systems exhibit low parallel efficiency and they are too expensive to be used easily for many research institutes. FPGA chips provide a new approach to accelerate the CYK algorithm by exploiting fine-grained custom design. The CYK algorithm shows complicated data dependence, in which the dependence distance is variable, and the dependence direction is also across two dimensions. We propose a systolic array structure including one master PE and multiple slave PEs for fine grain hardware implementation on FPGA. We partition tasks by columns and assign tasks to PEs for load balance. We exploit data reuse schemes to reduce the need to load matrix from external memory. To our knowledge, our implementation with 16 PEs is the only FPGA accelerator implementing the complete CYK/inside algorithm. The experimental results show a factor of more than 14 speedup over the Infernal-0.55 software running on a PC platform with Pentium 4 2.66GHz CPU. The computational power of our platform with FPGA accelerator is comparable to a PC cluster consisting of 20 Intel-Xeon CPUs for RNA secondary structure prediction using SCFGs, but the hardware cost and power consumption is only about 15% and 10% of the latter respectively. Copyright 2009 ACM.

关键词： Field programmable gate arrays (FPGA)

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Providing responsiveness requirement based consistency in DVE

Providing responsiveness requirement based consistency in DV...

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15th International Conference on parallel and distributed Systems, ICPADS '09

作者： Zhang, Wei Zhou, Hangjun Peng, Yuxing Li, Sikun National Laboratory for Parallel and Distributed Processing School of Computer Science ChangSha 410073 China

ISBN: (纸本)9780769539003

Consistency and responsiveness are two important factors in providing the sense of reality in distributed Virtual Environment (DVE). However, it is not easy to optimize both aspects because of the trade-off between these two factors. As a result, most existing consistency maintenance methods ignored the responsiveness requirements, or just assumed a simple responsiveness requirement model which cannot meet the real need of DVE systems. In this paper, we first present a new responsiveness requirement model. The model can describe requirement satisfaction situation of each node. Base on this model, we propose a responsiveness requirement based consistency method. The method can adjust the utilization of time resource according to the requirements of different nodes and improve the overall responsiveness performance by at least 20%. Therefore, it provides a good support to increase the applicability of DVE systems. © 2009 IEEE.

关键词： Economic and social effects

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A peer-to-peer media streaming system based on the iVCE platform

A peer-to-peer media streaming system based on the iVCE plat...

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15th International Conference on parallel and distributed Systems, ICPADS '09

作者： Wu, Jiqing Peng, Yuxing Shen, Rui National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

ISBN: (纸本)9780769539003

With the advancement of peer-to-peer technology, media streaming applications become more and more popular in the Internet. However, the traditional development methods for this kind of applications need developers not only to consider the application logic but also to manage the dynamics of Internet resources, thus increasing the difficulty of development and limiting the deployment of personal video distribution applications. In this paper, we design and implement a peer-to-peer streaming system in a much easier way. In this way we can concentrate on the application itself without distraction from the dynamics of Internet resources. Such simplification owes to the Internet-based Virtual Computing Environment (iVCE), which provides programming abstractions and runtime utilities that can encapsulate the complexity of managing transient resources into the platform, thus facilitating the construction of Internet applications. When we build our streaming application based on the iVCE, we only need to define the interaction protocols among distributed nodes with the Owlet programming language. Also, we implement a JavaBean, which can be used by the Owlet program, to assist the transfering and rendering of the content. Our implementation shows that peer-to-peer applications such as media streaming, can be elegantly built using the iVCE platform, and it can serve as a reference implementation for developing similar applications. © 2009 IEEE.

关键词： Media streaming

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