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Survey of DHT topology construction techniques in virtual computing environments

Science China(Information Sciences) 2011年第11期54卷 2221-2235页

作者： ZHANG YiMing 1,2,LU XiCheng 1,2 & LI DongSheng 1,21 national laboratory for parallel and distributed processing (PDL),Changsha 410073,China 2 School of computer,national University of Defense Technology,Changsha 410073,China 1. National Laboratory for Parallel and Distributed Processing (PDL) Changsha 410073 China2. School of Computer National University of Defense Technology Changsha 410073 China

The Internet-based virtual computing environment (iVCE) is a novel network computing *** characteristics of growth,autonomy,and diversity of Internet resources present great challenges to resource sharing in *** DHT overlay (DHT for short) technique has various advantages such as high scalability,low latency,and desirable availability,and is thus an important approach to realizing efficient resource *** construction is a key technique for structured overlays that realizes basic overlay functions including dynamic maintenance and message *** this paper,we first introduce the traditional techniques of DHT topology construction,focusing mainly on dynamic maintenance and message routing of typical DHTs,DHT indexing techniques for complex queries,and DHT grouping techniques for matching domain *** then present recent advances in DHT topology construction techniques in iVCE taking advantage of the characteristics of Internet ***,we discuss the future of DHT topology construction techniques.

关键词： virtual computing environments DHT overlays topology construction distributed indexing flexible routing

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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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2011 IEEE 3rd International Conference on Communication Software and Networks, ICCSN 2011

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

ISBN: (纸本)9781612844855

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. © 2011 IEEE.

关键词： Information management

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Automated WCET analysis based on program modes

Automated WCET analysis based on program modes

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1st International Workshop on Automation of Software Test, AST'06, Co-located with the 28th International Conference on Software Engineering, ICSE 2009

作者： Ji, Meng-Luo Wang, Ji Li, Shuhao Qi, Zhi-Chang School of Computer National University of Defense Technology China National Laboratory for Parallel and Distributed Processing China

ISBN: (纸本)1595934081

Program mode is a regular trajectory of the execution of a program that is determined by the values of its input variables. By exploiting program modes we may make Worst Case Execution Time (WCET) analysis more precise. This paper presents a novel method to automatically find program modes and calculate the WCET of programs. It consists of two phases. In phase one, we firstly automatically find the modes of a program by mode-relevant program slicing;then we compute the precondition for each mode using a path-wise test data generation method;after that, we can either conclude that it is an infeasible path, or get its precondition. In phase two, we calculate the WCET estimate of each given mode for modern RISC processors with caches and pipelines. The experiments are demonstrated to show the effectiveness of the method. Copyright 2006 ACM.

关键词： Real time systems

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UCBench: A user-centric benchmark suite for C code static analyzers

UCBench: A user-centric benchmark suite for C code static an...

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2012 IEEE International Conference on Information Science and Technology, ICIST 2012

作者： Liu, Jiangchao Chen, Liqian Dong, Longming Wang, Ji National Laboratory for Parallel and Distributed Processing School of Computer National University of Defence Technology Changsha China

ISBN: (纸本)9781457703454

In recent years, many C code static analyzers, with different abilities of bug detection, have appeared and been applied in various domains. There are so many choices that it becomes hard for programmers to know in detail the strengths as well as limitations of all these analyzers and to find the most suitable ones for their code. In this paper, we propose a benchmark for C code static analyzers, named UCBench, to provide quantitative and qualitative measurements for evaluating analyzers. Being different from other benchmarks, UCBench concentrates more on users' requirements rather than the improvements of bug detecting technique itself. The major components of UCBench include test case database, evaluation metrics and harness. We classify test cases into several groups according to their attributes and design various user-centric evaluation metrics. Besides, we develop some harness to automate the evaluation process. Finally, we demonstrate our benchmark suite over four C code static analyzers: Flawfinder, Cppcheck, Uno and Splint. © 2012 IEEE.

关键词： C (programming language)

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Automating software FMEA via formal analysis of dependence relations

Automating software FMEA via formal analysis of dependence r...

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32nd Annual IEEE International computer Software and Applications Conference, COMPSAC 2008

作者： Dong, Wei Wang, Ji Zhao, Changzhi Zhang, Xian Tian, Jie School of Computer National University of Defense Technology China National Laboratory for Parallel and Distributed Processing China

ISBN: (纸本)9780769532622

The paper presents the ongoing work of studying FMEA method for embedded safety critical software via formal analysis of various dependence relations among software elements, which can fairly improve the automation and precision of both system level and detailed level FMEA. These dependence relations are depicted by the formal models abstracted from software design and implementation, and the FMEA processes for both structural and object-oriented software are proposed respectively. The initial result of case study shows the effectiveness of the approach. I 2008 IEEE.

关键词： Safety engineering

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DFTracker: detecting double-fetch bugs by multi-taint parallel tracking

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Frontiers of computer Science 2019年第2期13卷 247-263页

作者： Pengfei WANG Kai LU Gen LI Xu ZHOU Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology Changsha 410073 China College of Computer National University of Defense Technology Changsha 410073 China Collaborative Innovation Center of High Performance Computing National University of Defense Technology Changsha 410073 China

A race condition is a common trigger for concurrency bugs. As a special case, a race condition can also occur across the kernel and user space causing a doublefetch bug, which is a field that has received little research attention. In our work, we first analyzed real-world doublefetch bug cases and extracted two specific patterns for doublefetch bugs. Based on these patter ns, we proposed an approach of multi-taint parallel tracking to detect double-fetch bugs. We also implemented a prototype called DFTracker (doublefetch bug tracker), and we evaluated it with our test suite. Our experiments demonstrated that it could effectively find all the double-fetch bugs in the test suite including eight realworld cases with no false negatives and minor false positives. In addition, we tested it on Linux kernel and found a new double-fetch bug. The execution overhead is approximately 2x for single-file cases and approximately 9x for the whole kernel test, which is acceptable. To the best of the authors1 knowledge, this work is the first to introduce multi-taint parallel tracking to double-fetch bug detection—an innovative method that is specific to double-fetch bug features—and has better path coverage as well as lower runtime overhead than the widely used dynamic approaches.

关键词： multi-taint parallel tracking double fetch race condition between kernel and user time of check to time of use real-world case analysis Clang Static Analyzer

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Impact of imprecise programming of memristor on building hardware neural network

Impact of imprecise programming of memristor on building har...

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2nd Annual Conference on Electrical and Control Engineering, ICECE 2011

作者： Zhu, Xuan National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology ChangSha China

ISBN: (纸本)9781424481637

The application of memristor in building hardware neural network has accepted widespread interests, and may bring novel opportunities to neural computing. However, due to the limitation of programming precision, the conductance of memristor which represents stored information may deviate from theoretical value, and thus bring error to the neural computing results. In this paper, we analyze the impact of imprecise programming on building hardeware neural network through Monte Carlo simulation on feedback layer model. The results show that the fault-tolerance ability of neural network could well adapt to these errors, which further proves the potential of building neural networks using memristors. © 2011 IEEE.

关键词： Errors

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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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A case study of SWIM: Optimization of memory intensive application on GPGPU

A case study of SWIM: Optimization of memory intensive appli...

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International Symposium on parallel Architectures, Algorithms, and Programming

作者： Yi, Wei Tang, Yuhua Wang, Guibin Fang, Xudong National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha China

ISBN: (纸本)9780769543123

Recently, GPGPU has been adopted well in the High Performance Computing (HPC) field. The limited global memory bandwidth poses a great challenge to many GPGPU programmers trying to exploit parallelism within the CPUGPU heterogeneous platform. In this paper, we choose SWIM, a typical memory intensive application from the SPEC OMP 2001 benchmark suite, for case study. We attempt to optimize the performance and energy consumption of the application utilizing different memory access mechanisms and present optimization methods including matrix transposition and kernel fusion. The experimental results on the Intel CoreTM i920 CPU plus GeForce GTX 295 platform shows that, the proposed optimizing methods achieve a speedup of 8.7X over the original OpenMP program and reduce the energy consumption by 83% for the problem size of 2048*2048. © 2010 IEEE.

关键词： Energy utilization

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Untrusted Hardware Causes Double-Fetch Problems in the I/O Memory

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Journal of computer Science & Technology 2018年第3期33卷 587-602页

作者： Kai Lu Peng-Fei Wang Gen Li Xu Zhou College of Computer National University of Defense Technology Changsha 410073 China Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology Changsha 410073 China Collaborative Innovation Center of High-Performance Computing National University of Defense Technology Changsha 410073 China

The double fetch problem occurs when the data is maliciously changed between two kernel reads of the supposedly same data, which can cause serious security problems in the kernel. Previous research focused on the double fetches between the kernel and user applications. In this paper, we present the first dedicated study of the double fetch problem between the kernel and peripheral devices （aka. the hardware double fetch）. Operating systems communicate with peripheral devices by reading from and writing to the device mapped I/O （input and output） memory. Owing to the lack of effective validation of the attached hardware, compromised hardware could flip the data between two reads of the same I/O memory address, causing a double fetch problem. We propose a static pattern-matching approach to identify the hardware double fetches from the Linux kernel. Our approach can analyze the entire kernel without relying on the corresponding hardware. The results are categorized and each category is analyzed using case studies to discuss the possibility of causing bugs. We also find four previously unknown double-fetch vulnerabilities, which have been confirmed and fixed after reporting them to the maintainers.

关键词： hardware double fetch double-fetch bug I/O memory peripheral device double-fetch vulnerability

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