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20th Annual Conference on Computer Engineering and Technology, NCCET 2016

作者： Zhang, Yang Xing, Zuocheng Liu, Cang Tang, Chuan Chen, Lirui Wang, Qinglin National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha China

ISBN: (纸本)9789811031588

The Synthetic Aperture Radar (SAR) system is a kind of modern high-resolution microwave imaging radar used in all-weather and all day long to provide remote sensing means and generate high resolution images of the land under illumination of radar beam. Unlike optical sensors, SAR algorithm needs a post-processing process on the data acquired to form the final image. In this article, we use the General Purpose Graphic processing Units (GPGPU) to accelerate two of SAR algorithms, PGA (Phase Gradient Autofocus) and PDE (Partial Differential Equations), which are two computational intensive algorithms in the post-processing process for the system. Our work shows that the GPU architecture has different acceleration effects on the two algorithms. PGA can achieve an acceleration of 21.7% and PDE can get a speed up of 2.58× on GPGPU. We analyse the reasons for the results and conclude that GPU is a promising platform to accelerate the SAR system. © Springer Nature Singapore Pte Ltd. 2016.

关键词： Synthetic aperture radar

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Automatic generation of fast BLAS3-GEMM: A portable compiler approach 17

Automatic generation of fast BLAS3-GEMM: A portable compiler...

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International Symposium on Code Generation and Optimization (CGO)

作者： Xing Su Xiangke Liao Jingling Xue College of Computer National Laboratory for Parallel and Distributed Processing Changsha China UNSW School of Computer Science and Engineering Sydney NSW Australia

ISBN: (纸本)9781509049318

GEMM is the main computational kernel in BLAS3. Its micro-kernel is either hand-crafted in assembly code or generated from C code by general-purpose compilers (guided by architecture-specific directives or auto-tuning). Therefore, either performance or portability suffers. We present a POrtable Compiler Approach, Poca, implemented in LLVM, to automatically generate and optimize this micro-kernel in an architecture-independent manner, without involving domain experts. The key insight is to leverage a wide range of architecture-specific abstractions already available in LLVM, by first generating a vectorized micro-kernel in the architecture-independent LLVM IR and then improving its performance by applying a series of domain-specific yet architecture-independent optimizations. The optimized micro-kernel drops easily in existing GEMM frameworks such as BLIS and OpenBLAS. Validation focuses on optimizing GEMM in double precision on two architectures. On Intel Sandybridge and AArch64 Cortex-A57, Poca's micro-kernels outperform expert-crafted assembly code by 2.35% and 7.54%, respectively, and both BLIS and OpenBLAS achieve competitive or better performance once their micro-kernels are replaced by Poca's.

关键词： Kernel Optimization Computer architecture Linear algebra Libraries Programming Program processors

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Dolphin: A search engine for OSS based on crowd discussions across communities 7

Dolphin: A search engine for OSS based on crowd discussions ...

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7th IEEE International Conference on Software Engineering and Service Science, ICSESS 2016

作者： Zhan, Yun Yin, Gang Wang, Tao Cheng, Yang Li, Zhixing Wang, Huaimin National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha China

ISBN: (纸本)9781467399036

The global open source software resources have become an Internet-scale repository, which provide abundant resources for software reuse. However, how to locate the desired resource efficiently and accurately from such large amounts is quite a challenge problem. Most of recent works barely focus on the semantic similarity by analyzing the software itself, which often result in inappropriate ranking. In this paper, we propose Dolphin, a global OSS search engine, which leverage the crowd discussions around OSS across communities for optimizing software ranking. Dolphin employs the crowd wisdom as an important factor and combines it with the semantic similarity to optimize search results ranking. We implement an OSS search engine based on the proposed approach, which provides online service continuously. Extensive experiments and user studies suggest the effectiveness of our approach. © 2016 IEEE.

关键词： Search engines

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Social computing in open source community: A study of software reuse 2nd

Social computing in open source community: A study of softwa...

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2nd International Conference on Young Computer Scientists, Engineers and Educators, ICYCSEE 2016

作者： Chen, Mengwen Wang, Tao Yang, Cheng Fan, Qiang Yin, Gang Wang, Huaimin National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha China

ISBN: (纸本)9789811020520

Software projects are not developed in isolation but often build upon other open source resources. These projects form a kind of reference ecosystem regarded as a software world. Most of social computing works focus on social networks such as Facebook and weibo to mine information. However, few previous works analyze Open Source Community which could help developers conduct collaborative development. In this paper, we model the Java reference ecosystem as a network based on the reuse relationships of GitHub-hosted Java projects and analyze the characteristics and the patterns of this reference ecosystem by using community detection and pattern discovery algorithms. Our study indicates that (1) Developers prefer to reuse software limited in only a small part of projects with cross cutting functionality or advanced applications. (2) Developers usually select software reused with similar function widely depending on different requirements, resulting to different patterns. Based on these collective intelligence, our study opens up several possible future directions of reuse recommendation, which are considered as guidance of collaborative development. © Springer Science+Business Media Singapore 2016.

关键词： Open source software

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False-positive probability and compression optimization for tree-structured bloom filters

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ACM Transactions on Modeling and Performance Evaluation of Computing Systems 2016年第4期1卷 1–39页

作者： Fu, Yongquan Biersack, Ernst National Key Laboratory for Parallel and Distributed Processing College of Computer Science National University of Defense Technology Sanyi Road Changsha Hunan Province410073 China CAIPY Valbonne06560 France

Bloom filters are frequently used to to check the membership of an item in a set. However, Bloom filters face a dilemma: the transmission bandwidth and the accuracy cannot be optimized simultaneously. This dilemma is particularly severe for transmitting Bloom filters to remote nodes when the network bandwidth is limited. We propose a novel Bloom filter called BloomTree that consists of a tree-structured organization of smaller Bloom filters, each using a set of independent hash functions. BloomTree spreads items across levels that are compressed to reduce the transmission bandwidth need. We show how to find optimal configurations for BloomTree and investigate in detail by how much BloomTree outperforms the standard Bloom filter or the compressed Bloom filter. Finally, we use the intersection of BloomTrees to predict the set intersection, decreasing the false-positive probabilities by several orders of magnitude compared to both the compressed Bloom filter and the standard Bloom filter. © 2016 ACM 2376-3639/2016/09-ART19 $15.00

关键词： Genetic algorithms

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An improved algorithm for reconstructing singular connection in the multi-block cfd applications

arXiv

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arXiv 2017年

作者： Yong-Xian, Wang Li-Lun, Zhang Yong-Gang, Che Chuan-Fu, Xu Wei, Liu Hua-Yong, Liu Zheng-Hua, Wang College of Computer National University of Defense Technology Changsha410073 China Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology Changsha410073 China State Key Laboratory of Aerodynamics Mianyang621000 China

In this paper, an improved algorithm is proposed for the reconstruction of singularity connectivity from the available pairwise connections during preprocessing phase. To evaluate the performance of our algorithm, an in-house CFD code, in which high-order finite-difference method for spatial discretization, running on the Tianhe-1A supercomputer is employed. Test cases with a varied amount of mesh points are chosen, and the test results indicate that the improved singular connection reconstruction algorithm can achieve a 2000× speedup at least compared with the naive search method adopt in the former version of our code. Moreover, the parallel efficiency can be benefited from the strategy of local communication based on the new algorithm. Copyright © 2017, The Authors. All rights reserved.

关键词： Finite difference method

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A novel open source software ecosystem: From a graphic point of view and its application 28

A novel open source software ecosystem: From a graphic point...

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28th International Conference on Software Engineering and Knowledge Engineering, SEKE 2016

作者： Song, Chenxi Wang, Tao Yin, Gang Zhang, Xunhui Yang, Cheng National Laboratory for Parallel and Distributed Processing College of Computer National University of Defense Technology Changsha China

ISBN: (纸本)189170639X

With the rapid development of open source software, various elements such as OSS, developers, users and online posts, across different communities and their interactions constitute a novel software ecosystem. Most of the current researches about software ecosystems care the connections between software, and few of them consider the relationship across communities from an overall perspective, and fail to cover the users and their activities which should be an indispensable part of the OSS ecosystem. This paper model the OSS ecosystem as a graph, which combines different types of OSS communities as a whole. Based on this graph model, we analyze the characteristics of ecosystem, like the evolution, competition and symbiosis. In addition, we build a recommendation system as well, and the experiment results suggest the validation of our approach. Copyright © 2016 by KSI Research Inc. and Knowledge Systems Institute Graduate School.

关键词： Ecosystems

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Large-scale virtual machines provisioning in clouds： challenges and approaches

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Frontiers of Computer Science 2016年第1期10卷 2-18页

作者： Zhaoning ZHANG Dongsheng LI Kui WU National Laboratory for Parallel and Distributed Processing School of Computer Science National University of Defense Technology Changsha 410073 China Computer Science Department University of Victoria Victoria V8W 2Y2 Canada

The scale of global data center market has been explosive in recent years. As the market grows, the demand for fast provisioning of the virtual resources to support elas- tic, manageable, and economical computing over the cloud becomes high. Fast provisioning of large-scale virtual ma- chines （VMs）, in particular, is critical to guarantee quality of service （QoS）. In this paper, we systematically review the existing VM provisioning schemes and classify them in three main categories. We discuss the features and research status of each category, and introduce two recent solutions, VMThunder and VMThunder＋, both of which can provision hundreds of VMs in seconds.

关键词： cloud computing IaaS large scale virtual ma-chine provisioning

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Learning non-local image diffusion for image denoising

arXiv

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arXiv 2017年

作者： Qiao, Peng Dou, Yong Feng, Wensen Chen, Yunjin National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha410073 China School of Automation and Electrical Engineering University of Science and Technology Beijing Beijing

Image diffusion plays a fundamental role for the task of image denoising. Recently proposed trainable nonlinear reaction diffusion (TNRD) model defines a simple but very effective framework for image denoising. However, as the TNRD model is a local model, the diffusion behavior of which is purely controlled by information of local patches, it is prone to create artifacts in the homogenous regions and over-smooth highly textured regions, especially in the case of strong noise levels. Meanwhile, it is widely known that the non-local selfsimilarity (NSS) prior stands as an effective image prior for image denoising, which has been widely exploited in many nonlocal methods. In this work, we are highly motivated to embed the NSS prior into the TNRD model to tackle its weaknesses. In order to preserve the expected property that end-to-end training is available, we exploit the NSS prior by a set of non-local filters, and derive our proposed trainable non-local reaction diffusion (TNLRD) model for image denoising. Together with the local filters and influence functions, the non-local filters are learned by employing loss-specific training. The experimental results show that the trained TNLRD model produces visually plausible recovered images with more textures and less artifacts, compared to its local versions. Moreover, the trained TNLRD model can achieve strongly competitive performance to recent state-of-theart image denoising methods in terms of peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM). Copyright © 2017, The Authors. All rights reserved.

关键词： Image denoising

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Pegasus：a distributed and load-balancing fingerprint identification system

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Frontiers of Information Technology & Electronic Engineering 2016年第8期17卷 766-780页

作者： Yun-xiang ZHAO Wan-xin ZHANG Dong-sheng LI Zhen HUANG Min-ne LI Xi-cheng LU National Laboratory for Parallel and Distributed Processing College of Computer National University of Defense Technology Changsha 410003 China

Fingerprint has been widely used in a variety of biometric identification systems in the past several years due to its uniqueness and immutability. With the rapid development of fingerprint identification techniques, many fingerprint identification systems are in urgent need to deal with large-scale fingerprint storage and high concurrent recognition queries, which bring huge challenges to the system. In this circumstance, we design and implement a distributed and load-balancing fingerprint identification system named Pegasus, which includes a distributed feature extraction subsystem and a distributed feature storage subsystem. The feature extraction procedure combines the Hadoop Image processing Interface（HIPI） library to enhance its overall processing speed; the feature storage subsystem optimizes MongoD B＇s default load balance strategy to improve the efficiency and robustness of *** and simulations are carried out, and results show that Pegasus can reduce the time cost by 70% during the feature extraction procedure. Pegasus also balances the difference of access load among front-end mongos nodes to less than 5%. Additionally, Pegasus reduces over 40% of data migration among back-end data shards to obtain a more reasonable data distribution based on the operation load（insertion, deletion, update, and query） of each shard.

关键词： distributed fingerprint identification distributed MongoD B Load balancing

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