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MilkyWay-2 supercomputer： system and application

Frontiers of Computer Science 2014年第3期8卷 345-356页

作者： Xiangke LIAO Liquan XIAO Canqun YANG Yutong LU 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

On June 17, 2013, MilkyWay-2 （Tianhe-2） supercomputer was crowned as the fastest supercomputer in the world on the 41th TOP500 list. This paper provides an overview of the MilkyWay-2 project and describes the design of hardware and software systems. The key architecture features of MilkyWay-2 are highlighted, including neo-heterogeneous compute nodes integrating commodity- off-the-shelf processors and accelerators that share similar instruction set architecture, powerful networks that employ proprietary interconnection chips to support the massively parallel message-passing communications, proprietary 16- core processor designed for scientific computing, efficient software stacks that provide high performance file system, emerging programming model for heterogeneous systems, and intelligent system administration. We perform extensive evaluation with wide-ranging applications from LINPACK and Graph500 benchmarks to massively parallel software deployed in the system.

关键词： MilkyWay-2 supercomputer petaflops computing neo-heterogeneous architecture interconnect network heterogeneous programing model system management benchmark optimization performance evaluation

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The TH Express high performance interconnect networks

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Frontiers of Computer Science 2014年第3期8卷 357-366页

作者： Zhengbin PANG Min XIE Jun ZHANG Yi ZHENG Guibin WANG Dezun DONG Guang SUO 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

Interconnection network plays an important role in scalable high performance computer （HPC） systems. The TH Express-2 interconnect has been used in MilkyWay-2 system to provide high-bandwidth and low-latency interprocessot communications, and continuous efforts are devoted to the development of our proprietary interconnect. This paper describes the state-of-the-art of our proprietary interconnect, especially emphasizing on the design of network interface. Several key features are introduced, such as user-level communication, remote direct memory access, offload collective operation, and hardware reliable end-to-end communication, etc. The design of a low level message passing infrastructures and an upper message passing services are also proposed. The preliminary performance results demonstrate the efficiency of the TH interconnect interface.

关键词： HPC network interface chip （NIC） TH Express nterconnect offload collective operation

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QSobel:A novel quantum image edge extraction algorithm

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Science China(Information Sciences) 2015年第1期58卷 107-119页

作者： ZHANG Yi LU Kai GAO YingHui Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology College of Computer National University of Defense Technology College of Electronic Science and Engineering National University of Defense Technology

Edge extraction is an indispensable task in digital image processing. With the sharp increase in the image data, real-time problem has become a limitation of the state of the art of edge extraction *** this paper, QSobel, a novel quantum image edge extraction algorithm is designed based on the flexible representation of quantum image(FRQI) and the famous edge extraction algorithm Sobel. Because FRQI utilizes the superposition state of qubit sequence to store all the pixels of an image, QSobel can calculate the Sobel gradients of the image intensity of all the pixels simultaneously. It is the main reason that QSobel can extract edges quite fast. Through designing and analyzing the quantum circuit of QSobel, we demonstrate that QSobel can extract edges in the computational complexity of O(n2) for a FRQI quantum image with a size of2 n × 2n. Compared with all the classical edge extraction algorithms and the existing quantum edge extraction algorithms, QSobel can utilize quantum parallel computation to reach a significant and exponential ***, QSobel would resolve the real-time problem of image edge extraction.

关键词： edge extraction quantum image processing FRQI Sobel computational complexity

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GPU acceleration of subgraph isomorphism search in large scale graph

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Journal of Central South University 2015年第6期22卷 2238-2249页

作者：杨博卢凯高颖慧王小平徐凯 Science and Technology on Parallel and Distributed Processing Laboratory National University of Defense Technology College of Computer National University of Defense Technology Department of Electronic Science and Engineering National University of Defense Technology

A novel framework for parallel subgraph isomorphism on GPUs is proposed, named GPUSI, which consists of GPU region exploration and GPU subgraph matching. The GPUSI iteratively enumerates subgraph instances and solves the subgraph isomorphism in a divide-and-conquer fashion. The framework completely relies on the graph traversal, and avoids the explicit join operation. Moreover, in order to improve its performance, a task-queue based method and the virtual-CSR graph structure are used to balance the workload among warps, and warp-centric programming model is used to balance the workload among threads in a warp. The prototype of GPUSI is implemented, and comprehensive experiments of various graph isomorphism operations are carried on diverse large graphs. The experiments clearly demonstrate that GPUSI has good scalability and can achieve speed-up of 1.4–2.6 compared to the state-of-the-art solutions.

关键词： parallel graph isomorphism GPU backtrack paradigm

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Computing Must and May Alias to Detect Null Pointer Dereference

Computing Must and May Alias to Detect Null Pointer Derefere...

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作者： Ma, Xiaodong Wang, Ji Dong, Wei National Laboratory for Parallel and Distributed Processing China

ISBN: (纸本)3540884785

This paper presents a novel algorithm to detect null pointer dereference errors. The algorithm utilizes both of the must and may alias information in a compact way to improve the precision of the detection. Using may alias information obtained by a fast flow- and context- insensitive analysis algorithm, we compute the must alias generated by the assignment statements and the must alias information is also used to improve the precision of the may alias. We can strong update more expressions using the must alias information, which will reduce the false positives of the detection for null pointer dereference. We have implemented our algorithm in the SUIF2 compiler infrastructure and the experiments results are as expected. © Springer-Verlag Berlin Heidelberg 2008.

关键词： Information use

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Towards estimating expected sizes of probabilistic skylines

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Science China(Information Sciences) 2011年第12期54卷 2574-2584页

作者： YANG YongTao & WANG YiJie national Key laboratory for parallel and distributed processing, School of Computer, national University of Defense Technology, Changsha 410073, China 1. National Key Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha 410073 China

We consider the maximal vector problem on uncertain data, which has been recently posed by the study on processing skyline queries over a probabilistic data stream in the database context. Let D n be a set of n points in a d-dimensional space and q (0 < q 1) be a probability threshold; each point in D n has a probability to occur. Our problem is concerned with how to estimate the expected size of the probabilistic skyline, which consists of all the points that are not dominated by any other point in D n with a probability not less than q. We prove that the upper bound of the expected size is O(min{n, (- ln q)(ln n) d-1 }) under the assumptions that the value distribution on each dimension is independent and the values of the points along each dimension are distinct. The main idea of our proof is to find a recurrence about the expected size and solve it. Our results reveal the relationship between the probability threshold q and the expected size of the probabilistic skyline, and show that the upper bound is poly-logarithmic when q is not extremely small.

关键词： probabilistic skyline probabilistic data streams expected size

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PartialRC: A Partial Recomputing Method for Efficient Fault Recovery on GPGPUs

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Journal of Computer Science & Technology 2012年第2期27卷 240-255页

作者：徐新海杨学军薛京灵林宇斐林一松 National Laboratory for Parallel and Distributed Processing School of ComputerNational University of Defense Technology Programming Languages and Compilers Group School of Computer Science and Engineering University of New South Wales

GPGPUs are increasingly being used to as performance accelerators for HPC （High Performance Computing） applications in CPU/GPU heterogeneous computing systems, including TianHe-1A, the world＇s fastest supercomputer in the TOP500 list, built at NUDT （national University of Defense Technology） last year. However, despite their performance advantages, GPGPUs do not provide built-in fault-tolerant mechanisms to offer reliability guarantees required by many HPC applications. By analyzing the SIMT （single-instruction, multiple-thread） characteristics of programs running on GPGPUs, we have developed PartialRC, a new checkpoint-based compiler-directed partial recomputing method, for achieving efficient fault recovery by leveraging the phenomenal computing power of GPGPUs. In this paper, we introduce our PartialRC method that recovers from errors detected in a code region by partially re-computing the region, describe a checkpoint-based faulttolerance framework developed on PartialRC, and discuss an implementation on the CUDA platform. Validation using a range of representative CUDA programs on NVIDIA GPGPUs against FullRC （a traditional full-recomputing Checkpoint-Rollback-Restart fault recovery method for CPUs） shows that PartialRC reduces significantly the fault recovery overheads incurred by FullRC, by 73.5% when errors occur earlier during execution and 74.6% when errors occur later on average. In addition, PartialRC also reduces error detection overheads incurred by FullRC during fault recovery while incurring negligible performance overheads when no fault happens.

关键词： GPGPU partial recomputing fault tolerance CUDA checkpointing

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Multi-Owner Keyword Search over Shared Data without Secure Channels in the Cloud

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China Communications 2017年第5期14卷 124-133页

作者： Yilun Wu Xicheng Lu Jinshu Su Peixin Chen Xiaofeng Wang Bofeng Zhang College of Computer National University of Defense TechnologyChangsha 410073China National Laboratory for Parallel and Distributed Processing National University of Defense TechnologyCbangsba 410073China

Searchable encryption allows cloud users to outsource the massive encrypted data to the remote cloud and to search over the data without revealing the sensitive information. Many schemes have been proposed to support the keyword search in a public cloud. However,they have some potential limitations. First,most of the existing schemes only consider the scenario with the single data owner. Second,they need secure channels to guarantee the secure transmission of secret keys from the data owner to data users. Third,in some schemes,the data owner should be online to help data users when data users intend to perform the search,which is *** this paper,we propose a novel searchable scheme which supports the multi-owner keyword search without secure channels. More than that,our scheme is a non-interactive solution,in which all the users only need to communicate with the cloud server. Furthermore,the analysis proves that our scheme can guarantee the security even without secure channels. Unlike most existing public key encryption based searchable schemes,we evaluate the performance of our scheme,which shows that our scheme is practical.

关键词： keyword search cloud security secure channels proxy re-encryption

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An optimized method for automatic test oracle generation from real-time specification

An optimized method for automatic test oracle generation fro...

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10th IEEE International Conference on Engineering of Complex Computer Systems, ICECCS 2005

作者： Wang, Xin Qi, Zhi-Chang Li, Shuhao National Laboratory for Parallel and Distributed Processing Changsha 410073 China

Test oracles are widely used to verify whether a system under test is running as desired. Since the correctness of real-time systems depends on the logical results of the computation and the time when results are produced at the same time, an optimized model checking-based method for test oracles generation is proposed to check if the system traces satisfy their real-time specifications at run time. Inspired by the idea of real-time model checking, the test oracles can be automatically generated from their specifications in the real-time logic MITL[0,d] in a simpler way and modelled by a variant of the Timed Automata. Assertions are chosen to acquire the traces of real-time systems. A case study is presented to demonstrate the usefulness of the method proposed in this paper. © 2005 IEEE.

关键词： Computer software selection and evaluation

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Improve OpenMP performance by extending BARRIER and REDUCTION constructs

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5th International Symposium on High Performance Computing, ISHPC 2003

作者： Chun, Huang Xuejun, Yang National Laboratory for Parallel and Distributed Processing China

ISBN: (纸本)3540203591

Barrier synchronization and reduction are global operations used frequently in large scale OpenMP programs. To improve OpenMP performance, we present two new directives BARRIER(0) and ALLREDUCTION to extend BARRIER and REDUCTION constructs in OpenMP API. The new extensions have been implemented on our portable OpenMP compiler on JIAJIA. Benchmark testing and experiments show that these constructs decrease the system overheads from synchronization, reduction operation and access of reduction variables on SDSM systems significantly. It is predicable that the improvement of performance can be obtained on ccNUMA systems. © Springer-Verlag Berlin Heidelberg 2003.

关键词： Application programming interfaces (API)

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