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International Conference on Computer Sciences and Convergence Information Technology (ICCIT)

作者： Yuan Yuan Shengyun Liu Yuxing Peng National Laboratory for Parallel and Distributed Processing College of Computer National University of Defense Technology Changsha China

Network coding brings a new solution for IP congestion control, since more than one buffered packets can be encoded together and removed as a coded packet. This may significantly decrease the packet loss during the congestion, but at the cost of building redundant paths. However, how to minimize the overhead of redundant paths turns out to be a NP-hard problem. In this paper, we propose a novel approximation algorithm called FlowGrouping, which transforms the redundant paths building problem into a limited clique partition problem by increasing edge weights, and can find a good approximate solution within O(n 3 ) computation time.

关键词： Encoding Partitioning algorithms Buildings Merging Approximation methods Network coding IP networks

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Error Detection by Redundant Transaction in Transactional Memory System

Error Detection by Redundant Transaction in Transactional Me...

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

作者： Wei Song Jia Jia Yu-xing Peng National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha China

This paper addresses the issue of error detection in transactional memory, and proposes a new method of error detection based on redundant transaction (EDRT). This method creates a transaction copy for every transaction, and executes both original transactions and transaction copies on adequate processor cores, and achieves error detection by comparing the execution results. EDRT utilizes the data-versioning mechanism of transactional memory to achieve the acquisition of an approximate minimum error detection comparing data set, and the acquisition is transparent and online. At last, this paper validates the EDRT through 5 test programs, including 4 SPLASH-2 benchmarks. The experimental results show that, the average error detecting cost is about 3.68% relative to the whole program, and it's only about 12.07% relative to the transaction parts of the program.

关键词： Instruction sets Fault tolerant systems Hardware Computer architecture Redundancy

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TRUSTIE: Design of a Trustworthy Software Production Environment

TRUSTIE: Design of a Trustworthy Software Production Environ...

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IEEE International Conference on Trust, Security and Privacy in Computing and Communications (TrustCom)

作者： Huaimin Wang National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha China

Internet fundamentally changes the model of software development, the demands of software quality, and the process of software resource sharing. Internet- based environment for trustworthy software production is recognized as a key topic of software engineering in both academic and software industry. In this paper, the concepts and models of trustworthy software are introduced which dominate the design of Trustie environment. Trustie provides trustworthy software components sharing by an evolving software repository, and provides collaborative software development in a customizable development platform powered by a software production line framework. Finally the layered practices of research and application based on Trustie preliminarily demonstrate the effectiveness as well as the promising future of this environment.

关键词： Software Production Collaboration Internet Resource management Software engineering Programming

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Understanding How Non-uniform Distribution of Memory Accesses on Cache Sets Affects the System Performance of Chip Multiprocessors

Understanding How Non-uniform Distribution of Memory Accesse...

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IEEE International Symposium on parallel and distributed processing with Applications Workshops (ISPAW)

作者： Xiaomin Jia Jiang Jiang Xiaoqiang Ni Tianlei Zhao Shubo Qi Guitao Fu Minxuan Zhang National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha China

Non-uniform distribution of memory accesses across cache sets has been recognized as one of the sources of inefficiency of cache architecture on single-core platform. Several schemes target the problem for performance boost. As chip multiprocessors (CMPs) pick up steam as the mainstream processor design choice, how non-uniform distribution of memory accesses across cache sets affects the cache management of CMPs is becoming an open question. We address the question by presenting several cache management schemes on CMP platforms, aiming at balance the memory access distribution across cache sets on shared caches or private caches. We show that on CMP platforms with multi-programmed workloads: (a) for shared caches, the non-uniform memory access distribution across different cache sets is biased by the fact that multiple applications are running concurrently and sharing the cache capacity. The scheme, which we put forward to make use of the non-uniformity to improve performance on shared caches, is proved to be of little to no benefit or even lead to degradation, (b) for caches that are organized as private caches, direct adaption of a scheme that targets this kind of non-uniformity outperforms the baseline private cache design by 2% on average, (c) however, for a private cache based cache management scheme we proposed, further effort to take advantage of this kind of non-uniformity for performance boost (on top of our proposed scheme) is also proved to be of little to no benefit. Therefore, We draw to the conclusion that on CMP platforms with multiprogrammed workloads, the non-uniform distribution of memory accesses across cache sets is partially circumvented by the interactions between multiple applications. Efforts seeking to make use of the non-uniformity to derive more benefit may end up in vain in CMPs.

关键词： Benchmark testing Throughput Arrays Hidden Markov models Indexes Memory management Protocols

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NBHU-based Method to Counter Quiet DDoS Attacks

NBHU-based Method to Counter Quiet DDoS Attacks

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2011 International Conference on Computer Science and Network Technology(2011计算机科学与网络技术国际会议 ICCSNT 2011)

作者： Jing Zhang Lin Chen Huaping Hu Hui Liu Computer School National University of Defense Technology Changsha China State Key Laboratory on Parallel and Distributed Processing National University of Defense Technolog

The Quiet DDoS attack becomes one of the most severely threat to the network safety, because this kind of attack completely adopts legal TCP flow while distributing its destination IP to evade various countermeasures deployed in the network. However, the high distributed degree of the destination IP becomes one characteristics of the attack. However, we think this characteristic make partially of the attack flow not match the behavior habit of network users. Inspired by this viewpoint, we propose a novel method to counter the Quiet DDoS attack based on the NBHU (network behavior habit of users). Furthermore, we carry on simulation of our method using NS2 platform, and the results show that this method can reduce the attack performance.

关键词： Quiet DDoS Attack Network Behavior Habit Counter

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Research on Online Failure Prediction Model and Status Pretreatment Method for Exascale System

Research on Online Failure Prediction Model and Status Pretr...

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International Conference on Cyber-Enabled distributed Computing and Knowledge Discovery, CyberC

作者： Hao Zhou Yanhuang Jiang National Laboratory of Parallel and Distributed Processing College of Computer Science National University of Defense Technology Changsha China

The reliability issue of Exascale system is extremely serious. Traditional passive fault-tolerant methods, such as rollback-recovery, can not fully guarantee system reliability any more because of their large executing overhead and long recovering duration. Active fault tolerance is expected to become another important fault-tolerant approach for Exascale system. Focusing on system failure prediction, which is one key step of active fault tolerance, we construct online failure prediction model and research on the effective method of system status pretreatment. In order to improve the accuracy and real-time feature of current methods, the proposed Improved Adaptive Semantic Filter (IASF) method processes the latest system logs regularly, filtering useless information out of them according to their semantics. Adopting the main idea of Vector Space Model (VSM), IASF method creates Event Vector corresponding to each log record. By calculating the cosine of vectorial angle, it evaluates the semantics correlation between different log records, and then executes temporal and spatial redundant filter considering the burst feature of log records. IASF method is insensitive to the type of system log and does not introduce any expert system or domain knowledge. The experiment result shows that system can eliminate about 99.6% of useless log records after executing IASF method.

关键词： Fault tolerance Fault tolerant systems Vectors Correlation Information filters Predictive models

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Coordinate strip-mining and kernel fusion to lower power consumption on GPU

Coordinate strip-mining and kernel fusion to lower power con...

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Design, Automation and Test in Europe Conference and Exhibition

作者： Guibin Wang National Laboratory of Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha Hunan China

ISBN: (纸本)9781612842080

Although general purpose GPUs have relatively high computing capacity, they also introduce high power consumption compared with general purpose CPUs. Therefore low-power techniques targeted for GPUs will be one of the most hot topics in the future. On the other hand, in several application domains, users are unwilling to sacrifice performance to save power. In this paper, we propose an effective kernel fusion method to reduce the power consumption for GPUs without performance loss. Different from executing multiple kernels serially, the proposed method fuses several kernels into one larger kernel. Owing to the fact that most consecutive kernels in an application have data dependency and could not be fused directly, we split large kernel into multiple slices with strip-mining method, then fuse independent sliced kernels into one kernel. Based on the CUDA programming model, we propose three different kernel fusion implementations, with each one targeting for a special case. Based on the different strip-ming methods, we also propose two fusion mechanisms, which are called invariant-slice fusion and variant-slice fusion. The latter one could be better adapted to the requirements of the kernels to be fused. The experimental results validate that the proposed kernel fusion method could effectively reduce the power consumption for GPU.

关键词： Kernel Energy consumption Graphics processing unit Power demand Instruction sets Programming Optimization

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Fault recovery based on parallel recomputing in transactional memory system

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Lecture Notes in Electrical Engineering 2011年 98卷 995-1002页

作者： Song, Wei Jia, Jia National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha410073 China

ISBN: (纸本)9783642217647

This paper addresses the issue of fault recovery in transactional memory, and proposes a method of fault recovery based on parallel recomputing in transactional memory system. This method utilizes the dataversioning mechanism of transactional memory system to avoid the extra cost of state saving, rolls back a single transaction to avoid wasting the computing time of the fault-free transactions, and adopts the parallel recomputing method to reduce the cost of fault recovery. This paper applies this method to OpenTM programs, and proposes the implementation method of parallel recomputing in OpenTM. At last, this paper tests the performance of this method through a test program. The experimental results show that, compared with the fault recovery method of rolling back a single transaction, the parallel recomputing method in transactional memory system can execute the fault recovery quickly and accurately and the method has a well scalability. © Springer-Verlag Berlin Heidelberg 2011.

关键词： Fault tolerance

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A Hierarchical Memory Service Mechanism in Server Consolidation Environment

A Hierarchical Memory Service Mechanism in Server Consolidat...

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International Conference on parallel and distributed Systems (ICPADS)

作者： Liufeng Wang Huaimin Wang Lu Cai Rui Chu Pengfei Zhang Lanzheng Liu National Key Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha China School of Economics and Management Xi'an University Xi'an China

Increasing Internet business and computing footprint motivate server consolidation in data centers. Through virtualization technology, server consolidation can reduce physical hosts and provide scalable services. However, the ineffective memory usage among multiple virtual machines (VMs) becomes the bottleneck in server consolidation environment. Because of inaccurate memory usage estimate and the lack of memory resource managements, there is much service performance degradation in data centers, even though they have occupied a large amount of memory. In order to improve this scenario, we first introduce VM's memory division view and VM's free memory division view. Based on them, we propose a hierarchal memory service mechanism. We have designed and implemented the corresponding memory scheduling algorithm to enhance memory efficiency and achieve service level agreement. The benchmark test results show that our implementation can save 30% physical memory with 1% to 5% performance degradation. Based on Xen virtualization platform and balloon driver technology, our works actually bring dramatic benefits to commercial cloud computing center which is providing more than 2,000 VMs' services to cloud computing users.

关键词： Memory management Resource management Servers Scheduling algorithm Benchmark testing Cloud computing System performance

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Context-Aware Scheduling in Wireless Networks with Successive Interference Cancellation

Context-Aware Scheduling in Wireless Networks with Successiv...

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IEEE International Conference on Communications Workshops

作者： Shaohe Lv Weihua Zhuang Xiaodong Wang Xingming Zhou National Laboratory of Parallel and Distributed Processing National University of Defense Technology Department of Electrical and Computer Engineering University of Waterloo

ISBN: (纸本)9781612842325

We consider the greedy scheduling based on the physical model in wireless networks with successive interference cancellation (SIC). There are two major stages in a scheduling scheme, link selection (to decide which link is scheduled next) and time slot selection (to deciding which slot is allocated to a given link). Most available schemes take a first-fit policy in the latter and strive to achieve good performance by careful selection of link ordering with respect to interference. Due to the accumulation effect and sequential detection nature of SIC, however, it is difficult to evaluate the interference of a link. As a result, many existing scheduling schemes become less efficient. In this paper, we take a new look on the problem and focus to the time slot selection stage. We define tolerance margin to measure the saturation of a link set and present two heuristic policies: one is to schedule a link to a slot such that the resulting set of links has a maximum tolerance margin;the other is to choose a slot such that the increase of tolerance margin is minimum. Simulation results show that the performance of the proposed schemes is better than the first-fit policy and is close to the optimal solution.

关键词： Link scheduling Successive interference cancellation Physical interference model

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