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作者： Lu, Kai Zhou, Xu Bergan, Tom Wang, Xiaoping Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology Changsha China College of Computer National University of Defense Technology Changsha China University of Washington Computer Science and Engineering United States

Multithreaded programs execute nondeterministically on conventional architectures and operating systems. This complicates many tasks, including debugging and testing. Deterministic multithreading (DMT) makes the output of a multithreaded program depend on its inputs only, which can totally solve the above problem. However, current DMT implementations suffer from a common inefficiency: they use frequent global barriers to enforce a deterministic ordering on memory accesses. In this paper, we eliminate that inefficiency using an execution model we call deterministic lazy release consistency (DLRC). Our execution model uses the Kendo algorithm to enforce a deterministic ordering on synchronization, and it uses a deterministic version of the lazy release consistency memory model to propagate memory updates across threads. Our approach guarantees that programs execute deterministically even when they contain data races. We implemented a DMT system based on these ideas (RFDet) and evaluated it using 16 parallel applications. Our implementation targets C/C++ programs that use POSIX threads. Results show that RFDet gains nearly 2x speedup compared with DThreads-a start-of-the-art DMT system. © 2014 ACM.

关键词： C++ (programming language)

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A piecewise-based contrast enhancement framework for low lighting video

A piecewise-based contrast enhancement framework for low lig...

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International Conference on Security, Pattern Analysis, and Cybernetics (SPAC)

作者： Dongsheng Wang Xin Niu Yong Dou National Laboratory for Parallel & Distributed Processing National University of Defense Technology Changsha China

In this paper, we propose an efficient automatic contrast enhancement algorithm for low lighting video. The algorithm is based on a piecewise stretch on the brightness component extracted with Retinex theory in HSV space to improve the visuality of the image. By dividing the brightness component into dark and bright part, nonlinear transformations with different distribution assumption were performed respectively. All the model parameters were estimated automatically according to the illumination conditions. We use two methods to estimate the brightness. The one is global illumination estimation and the other is local illumination estimation. In comparison with global estimation, a local illumination estimation method is proposed for the further improvement. Experiments show that the algorithm can achieve satisfactory effect for nighttime image or video enhancement by comparing with some state-of-the-art approaches.

关键词： Brightness Lighting Estimation Histograms Transforms Real-time systems Image color analysis

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Accelerating Embarrassingly parallel Algorithm on Intel MIC

Accelerating Embarrassingly Parallel Algorithm on Intel MIC

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2014 IEEE International Conference on Progress in Informatics and Computing

作者： Qinglin Wang Jie Liu XiantuoTang Feng Wang Guitao Fu Zuocheng Xing Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology

The Embarrassingly parallel(EP) algorithm which is typical of many Monte Carloapplications provides an estimate of the upper achievable limits for double precision performance of parallel supercomputers. Recently, Intel released Many Integrated Core(MIC) architecture as a many-core co-processor. MIC often offers more than 50 cores each of which can run four hardware threads as well as 512-bit vector instructions. In this paper,we describe how the EP algorithm is accelerated effectively on the platforms containing MIC using the offload execution model. The result shows that the efficientimplementation of EP algorithm on MIC can take full advantage of MIC's computational resources and achieves a speedup of 3.06 compared with that on Intel Xeon E5-2670 CPU. Based on the EP algorithm on MIC and an effective task distribution model, the implementation of EP algorithm on a CPU-MIC heterogeneous platform achieves the performance of up to2134.86 Mop/s and 4.04 times speedup compared with that on Intel Xeon E5-2670 CPU.

关键词： NPB embarrassingly parallel algorithm heterogeneous platform many integrated core architecture

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CCH-MAC: Evading hidden terminal in ad-hoc network

CCH-MAC: Evading hidden terminal in ad-hoc network

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International Conference on Information and Communication Technology Convergence (ICTC)

作者： Xuan Dong Shaohe Lv Yong Lu Xiaodong Wang Xingming Zhou National Laboratory of Parallel and Distributed Processing University of Defense Technology Chansha China

Hidden terminal and collisions are well-known problems due to broadcasting nature of wireless network. In this paper, we address an efficient MAC protocol to evade the potential collisions caused by hidden terminals, where advanced phycical layer technique, full-duplex, is exploited to coordinate channel contention among nodes within two-hops range. Furhter-more, cooperative channel hopping(CCH) MAC is developed to improve the frequency efficiency by limiting the interference of hidden terminals and enabling a collision-free channel for further transmission. Basically, a fined channel hopping mechanism is proposed to avoid the continually interference and cooperative coordination is subjoined by the transmission of cyclic prefix. To the best of our knowledge, CCH-MAC validates the detection of subchannel contention on NI USRPs and evaluation via simulations shows that CCH-MAC achieves at least 35% throughput gain over FICA with a slightly loss in fairness.

关键词： Transmitters Interference Throughput Receivers Network topology Decoding Indexes

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CoCache: Multi-layer Multi-path Cooperative Cache Accelerating the Deployment of Large Scale Virtual Machines

CoCache: Multi-layer Multi-path Cooperative Cache Accelerati...

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2014 IEEE 8th International Symposium on Service Oriented System Engineering

作者： Ziyang Li Zhaoning Zhang Huiba Li Yuxing Peng National Key Laboratory for Parallel and Distributed Processing National University of Defense Technology China

By analyzing the problems and challenges of virtual machine image store system in cloud computing environment, we present a cooperative persistent cache (CoCache) for virtual disks. CoCache takes advantage of the service ability of the cached nodes by providing virtual image data service for other nodes. CoCache can transfer data between nodes in a P2P pattern, for extending data service ability of the system. CoCache is realized in the kernel space of Linux, can support any kind of VMM. Experiments show that CoCache can effectively reduce the cost during virtual machines read data, and promote the service ability of virtual machine storage system. Layer-aware cache policy is proposed specially for improving cache hit rate in the multi-layer and multipath environment.

关键词： Virtual machining Servers Image storage Cloud computing Computer architecture System performance Cache storage

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Design and Implementation of distributed Stage DB:A High Performance distributed Key-Value Database

Design and Implementation of Distributed Stage DB:A High Per...

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2014 International Conference on Industrial Engineering and Information Technology

作者： Hui-jun Wu Kai Lu Gen Li Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology

With the development of high performance computing and Web 2.0 applications,unstructured data storage becomes more and more *** RDBMS isn't efficient for big data ***,RDBMS's scalability is ***' expansion often leads to a large scale of data *** paper designs and implements a high performance distributed key-value database,which is distributed Stage *** servers are organized by a consistent hashing ring and distributed with the support of Zookeeper,a distributed service *** has a high single-node read/write *** route information is calculated by clients,which reduces the expense of expansion.

关键词： distributed system,database,key-value,Zookeeper

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3D Pipeline Contention: Asymmetric Full Duplex in Wireless Networks

3D Pipeline Contention: Asymmetric Full Duplex in Wireless N...

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IEEE International Conference on Computer Communications

作者： Shaohe Lv Xuan Dong Yong Lu Xiaoli Du Xiaodong Wang Yong Dou Xingming Zhou National Laboratory of Parallel and Distributed Processing National University of Defense Technology Changsha Hunan China

Coordination among users is an indispensable part in wireless networks for efficient medium access. Alone with the rapid increase of transmission rate, however, coordination time becomes insufferable. We present AFD, namely asymmetric full duplex, to achieve high coordination efficiency at nearly zero overhead. In AFD, channel contention is performed simultaneously with data transmission. We propose a 3D pipeline contention scheme where the contention process is divided into several parallel stages and executed in a pipelined manner in a 3D domain specified by time, frequency and spatial antenna. To mitigate the interference between the data packet and the contention signal, we adopt a singleton PN sequence as a contention pilot. AFD provides a novel network-scale full duplex capability. The performance is evaluated by both simulations and measurements in a testbed. AFD outperforms IEEE 802.11 significantly, i.e., the Jain's fairness index is around 0.95 with a throughput gain up to 120%.

关键词： Pipelines Data communication Antennas Three-dimensional displays Interference IEEE 802.11 Standards Time-frequency analysis

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Signature-based fast access coordination in multicarrier wireless networks

Signature-based fast access coordination in multicarrier wir...

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General Assembly and Scientific Symposium, URSI

作者： Shaohe Lv Xuan Dong Hu Shen Xiaodong Wang Xingming Zhou National Laboratory of Parallel and Distributed Processing National University of Defense Technology Changsha Hunan China

Coordination among users is an indispensable part in wireless networks for efficient access control. Alone with the rapid increase of the data transmission rate, however, coordination time becomes insufferable, even several times higher than that for data transmission. We present SIF, a signature-based frequency-domain contention mechanism to achieve high coordination efficiency with low overhead. In SIF, different user is assigned by a different PN sequence as a signature. A contending user issues its signature on some specific OFDM subcarriers and uses the binary sequence of the ON/OFF states of all OFDM subcarriers to deliver the contend information. A signature-based detection method is proposed to detect the CVs of other nodes quickly and reliably. It is shown that, the collision probability of SIF is very low even in a large wireless networks, e.g., less than 0.2% with 100 users. Moreover, as SIF can complete the coordination within one slot in most cases, the throughput gain is up to 200% in comparison with 802.11.

关键词： IEEE 802.11 Standards Vectors Wireless networks OFDM Throughput Data communication Frequency-domain analysis

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Who should review this pull-request: Reviewer recommendation to expedite crowd collaboration 21

Who should review this pull-request: Reviewer recommendation...

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21st Asia-Pacific Software Engineering Conference, APSEC 2014

作者： Yu, Yue Wang, Huaimin Yin, Gang Ling, Charles X. National Laboratory for Parallel and Distributed Processing College of Computer National University of Defense Technology Changsha410073 China Department of Computer Science University of Western Ontario LondonONN6A 5B7 Canada

ISBN: (纸本)9781479974252

Github facilitates the pull-request mechanism as an outstanding social coding paradigm by integrating with social media. The review process of pull-requests is a typical crowdsourcing job which needs to solicit opinions of the community. Recommending appropriate reviewers can reduce the time between the submission of a pull-request and the actual review of it. In this paper, we firstly extend the traditional Machine Learning (ML) based approach of bug triaging to reviewer recommendation. Furthermore, we analyze social relations between contributors and reviewers, and propose a novel approach to recommend highly relevant reviewers by mining comment networks (CN) of given projects. Finally, we demonstrate the effectiveness of these two approaches with quantitative evaluations. The results show that CN-based approach achieves a significant improvement over the ML-based approach, and on average it reaches a precision of 78% and 67% for top-1 and top-2 recommendation respectively, and a recall of 77% for top-10 recommendation. © 2014 IEEE.

关键词： Learning systems

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Experimental verification of the parasitic bipolar amplification effect in PMOS single event transients

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Chinese Physics B 2014年第7期23卷 775-779页

作者： He Yi-Bai Chen Shu-Ming College of Computer National University of Defense Technology Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology

The contribution of parasitic bipolar amplification to SETs is experimentally verified using two P-hit target chains in the normal layout and in the special layout. For PMOSs in the normal layout, the single-event charge collection is composed of diffusion, drift, and the parasitic bipolar effect, while for PMOSs in the special layout, the parasitic bipolar junction transistor cannot turn on. Heavy ion experimental results show that PMOSs without parasitic bipolar amplification have a 21.4% decrease in the average SET pulse width and roughly a 40.2% reduction in the SET cross-section.

关键词：重离子实验放大效应单事件双极寄生 PMOS 验证瞬态

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