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International Symposium on parallel Architectures, Algorithms and Networks (ISPAN)

作者： Feng Liu Yuxing Peng Xicheng Lu Parallel and Distributed Processing Laboratory School of Computer Science and Technology National University of Defense Technology Changsha China

Building application level multicast (ALM) for media streaming, we had better keep the invariability of source to-end delay (S2EDelay) of any node on the tree, so as to avoid delay jitter problem. In this paper, we proposed an aggregation-based ALM architecture, which aggregates the unstable nodes within a local area into a relative stable aggregation node Anode, and then builds tree by Anodes. Anode shields node's dynamicity inside and behaves as a stable one outside. To build the architecture, we first proposed an Anode structure by n-dimension anti-cube, and proposed a distributed algorithm to bind the logic view and physical view of an Anode dynamically by the differentiation and assimilation operations, which maintain the integrality of the logic view while the physical view changes dynamically. Experiment results indicate that our algorithm can keep the S2EDelay invariability of the built ALM tree effectively.

关键词： Streaming media Anodes Delay Stability Application software Jitter distributed algorithms Logic Internet Network topology

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Providing Responsiveness Requirement Based Consistency in DVE

Providing Responsiveness Requirement Based Consistency in DV...

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International Conference on parallel and distributed Systems (ICPADS)

作者： Wei Zhang Hangjun Zhou Yuxing Peng Sikun Li National Laboratory of Parallel and Distributed Processing School of Computer Science National University of Defense Technology Changsha China

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.

关键词： Delay effects Virtual environment distributed processing Computer science Games Distance learning Electronic commerce Safety Research and development Real time systems

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Combining model and iterative compilation for program performance optimization

Journal of Software

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Journal of Software 2009年第3期4卷 240-246页

作者： Lu, Pingjing Che, Yonggang Wang, Zhenghua National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha 410073 China

The performance gap for high performance applications has been widening over time. High level program transformations are critical to improve applications' performance, many of which concern the determination of optimal values for transformation parameters, such as loop unrolling and blocking. Static approaches achieve these values based on analytical models that are hard to achieve because of increasing architecture complexity and code structures. Recent iterative compilation approaches achieve it by executing different versions of the program on actual platforms and select the one that renders best performance, outperforming static compilation approaches significantly. But the expensive compilation cost has limited their application scope to embedded applications and a small group of math kernels. This paper proposes a combinative approach--Combining Model and Iterative Compilation for Program Performance Optimization (CMIC). Such an approach first constructs a program optimization transformation model based on hardware performance counters to decide how and when to apply transformations, and then selects the optimal transformation parameters using Nelder-Mead simplex algorithm. Experimental results show that our approach can effectively improve programs' floating-point performance, reducing programs' runtime, therefore, lessening the performance gap for high-performance applications. © 2009 ACADEMY PUBLISHER.

关键词： Digital arithmetic

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FPGA accelerating three QR decomposition algorithms in the unified pipelined framework

FPGA accelerating three QR decomposition algorithms in the u...

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International Conference on Field Programmable Logic and Applications

作者： Yong Dou Jie Zhou Xiaoyang Chen Yuanwu Lei Jinbo Xu National Laboratory of Parallel & Distributed Processing National University of Defense Technology Changsha China

Many FPGA implementations for QR decomposition have been studied on small-scale matrix and all of them are presented individually. However to the best of our knowledge, there is no FPGA-based accelerator for large-scale QR decomposition. In this paper, we propose a unified FPGA accelerator structure for large-scale QR decomposition. To exploit the computational potential of FPGA, we introduce a fine-grained parallel algorithm for QR decomposition. A scalable linear array processing elements (PEs), which is the core component of the FPGA accelerator, is proposed to implement this algorithm. A total of 15 PEs can integrated into an Altera StratixII EP2S130F1020C5 on our self-designed board. Experimental results show that a factor of 4 speedup and the maximum powerperformance of 60.9 can be achieved compare to Pentium Dual CPU with double SSE thread.

关键词： Field programmable gate arrays Acceleration Pipelines Signal processing algorithms Large-scale systems Concurrent computing parallel algorithms Yarn Hardware Central processing Unit

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Fault Tolerant parallel FFT Using parallel Failure Recovery

Fault Tolerant Parallel FFT Using Parallel Failure Recovery

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International Conference on Computational science and its Applications (ICCSA)

作者： Hongyi Fu Xuejun Yang National Laboratory of Parallel and Distributed Processing National University of Defense Technology Changsha China

This paper introduces a new method based on parallel failure recovery, for the fault tolerance issue of parallel programs. In case a process fails, other surviving processes will compute the task of the failed one in parallel, so that the overhead for fault tolerance is leveled down. The paper presents the design and implementation of the parallel FFT using the new approach, and works on finding an optimum number of processes that participate in parallel failure recovery. Finally, an experiment is done to show the better performance of the parallel failure recovery over that of checkpointing, and to show the effectiveness of our solution for the best number of processes participating parallel failure recovery.

关键词： Fault tolerance Application software Grid computing Conferences Computer networks Physics computing Aerospace industry Computational geometry High performance computing Books

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Transmission Scheduling in Data-Driven Peer-to-Peer Streaming towards Optimal Throughput

Transmission Scheduling in Data-Driven Peer-to-Peer Streamin...

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International Conference on Networking, Architecture, and Storage (NAS)

作者： Jiqing Wu Yuxing Peng Feng Liu National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha China

Peer-to-peer media streaming has been an important service on the internet in recent years. The Data-driven (or mesh-based) structure is adopted by most working systems,in which data scheduling is one of the important ***, those frequently used scheduling algorithms are often faced with such a case: A neighbor peer takes up its bandwidth to deliver the packets that other neighbors can also supply, but some packets only held by it are not *** packets can not be delivered in the current scheduling cycle, even though that the other neighbors have surplus bandwidth. This is a kind of waste of bandwidth and decreases the throughput of transmission. In this paper we propose anew scheduling algorithm aiming at the optimal throughput:Bipartite-matching based Block Scheduling algorithm(BBS).We convert the original data scheduling problem to a problem of finding a maximum match on the correspond bipartite graph, then assign data packets to neighbors according to the maximum match. We evaluate the performance of BBS with extensive experiments and the results show that BBS throughput and provides better streaming quality than those frequently used scheduling algorithms.

关键词： Peer to peer computing Throughput Bandwidth Scheduling algorithm Streaming media Laboratories distributed processing IP networks Web and internet services Bipartite graph

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Fast query over encrypted data based on B+ tree

Fast query over encrypted data based on B+ tree

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2009 International Conference on Apperceiving Computing and Intelligence Analysis, ICACIA 2009

作者： Wang, Zheng-Fei Tang, Ai-Guo Wang, Wei Department of Computer Hunan Business College Changsha 410205 China National Key Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha 410073 China School of Computer Science Fudan University Shanghai 200433 China

ISBN: (纸本)9781424452040

There are a lot of important and sensitive data in databases, which need to be protected from attacks. To secure the data, Cryptography support is an effective mechanism. However, a tradeoff must be made between the performance and the security because encryption and decryption greatly degrade the query performance. In this paper, a framework is proposed that can quickly implement query over encrypted data based on B+ tree. When data are stored in the form of cipher, it not only stores the encrypted data themselves, but also creates a B+ tree index for the data before encrypting them. When querying the encrypted data, firstly, it locates the encrypted records related to the querying predicate based on the B+ tree index;secondly, it decrypts the encrypted records to accomplish the results. Meanwhile, it must encrypt the B+ tree itself to protect it from leaking confidential information. According to the structure of the B+ tree, it encrypts each node of the B+ tree separately. The results of experiments show that the query performance over the encrypted data decreases about 20 percent compared with the plaintext query performance, and validate the functionality and usability of our approach. ©2009 IEEE.

关键词： Cryptography

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Exploiting Fine-Grained Pipeline parallelism for Wavefront Computations on Multicore Platforms

Exploiting Fine-Grained Pipeline Parallelism for Wavefront C...

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International Conference on parallel processing Workshops (ICPPW)

作者： Guiming Wu Miao Wang Yong Dou Fei Xia National Laboratory for Parallel & Distributed Processing National University of Defense Technology Changsha China

This paper presents our experience with exploiting fine-grained pipeline parallelism for wavefront computations on a multicore platform. Wavefront computations have been widely applied in many application areas such as scientific computing algorithms and dynamic programming algorithms. To exploit fine-grained parallelism on multicore platforms, the programmers must consider the problems of synchronization, scheduling strategies and data locality. This paper shows the impact of fine-grained synchronization methods, scheduling strategies and data tile sizes on performance. We propose a low cost, lock-free, and lightweight synchronization method that can fully exploit pipeline parallelism. Our evaluation shows that RNAfold, an application for RNA secondary structures prediction, can achieve the best speedup of 3.88 on four cores under our framework.

关键词： Pipelines parallel processing Concurrent computing Multicore processing Heuristic algorithms Processor scheduling Scientific computing Dynamic programming Programming profession Tiles

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A Fine-grained Pipelined Implementation of the LINPACK Benchmark on FPGAs

A Fine-grained Pipelined Implementation of the LINPACK Bench...

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Annual IEEE Symposium on Field-Programmable Custom Computing Machines (FCCM)

作者： Guiming Wu Yong Dou Yuanwu Lei Jie Zhou Miao Wang Jingfei Jiang National Laboratory of Parallel & Distributed Processing National University of Defense Technology Changsha China

Previous works have projected that the peak performance of FPGAs can outperform that of the general purpose processors. However, no work actually compares the performance between FPGAs and CPUs using the standard benchmarks such as the LINPACK benchmark. We propose and implement an FPGA-based hardware design of the LINPACK benchmark, the key step of which is LU decomposition with pivoting. We introduce a fine-grained pipelined LU decomposition algorithm that enables optimum performance by exploiting fine-grained pipeline parallelism. A scalable linear array of processing elements (PEs), which is the core component of our hardware design, is proposed to implement this algorithm. To the best of our knowledge, this is the first reported FPGA-based pipelined implementation of LU decomposition with pivoting. A total of 19 PEs can be integrated into an Altera Stratix II EP2S130F1020C5 on our self-designed development board. Experimental results show that the speedup up to 6.14 can be achieved relative to a Pentium 4 processor for the LINPACK benchmark.

关键词： Field programmable gate arrays Hardware Equations Algorithm design and analysis Concurrent computing distributed computing Laboratories distributed processing Pipelines parallel processing

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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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International Conference on parallel and distributed Systems (ICPADS)

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

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 transferring 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.

关键词： Streaming media Peer to peer computing Internet Resource management Logic Utility programs Runtime environment Environmental management Protocols Computer languages

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