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作者： Chen, Zhuan Xiong, Jin Meng, Dan National Research Center for Intelligent Computing Systems Institute of Computing Technology Chinese Academy of Sciences China Graduate University of Chinese Academy of Sciences China Department of Computer Science University of Rochester United States

ISBN: (纸本)9780769542201

In cluster file systems, the metadata management is critical to the whole system. Past researches mainly focus on journaling which alone is not enough to provide high-available metadata service. Some others try to use replication, but the extra latency accompanied is a main problem. To guarantee both availability and efficiency, we propose a mechanism for building highly available metadata servers based on replication, which integrates Paxos algorithm effectively into metadata service. The Packed Multi-Paxos is proposed to reduce the latency brought by replication, which is self-adaptive and can make the replication to achieve high throughput under heavy client load and low latency under light client load. By designing efficient architecture and coordination mechanism, all replica server nodes simultaneously provide metadata read-access service. This high-available mechanism could decrease the impact of server failures and there is no interruption of service. The performance results show that the latency caused by replication and redundancy is well under control, and the performance of metadata read operation gains improvement. © 2010 IEEE.

关键词： Metadata

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Jedule: A tool for visualizing schedules of parallel applications

Jedule: A tool for visualizing schedules of parallel applica...

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International Workshop on Scheduling and Resource Management for Parallel and Distributed Systems

作者： Hunold, Sascha Hoffmann, Ralf Suter, Frédéric International Computer Science Institute Berkeley CA United States Department of Computer Science University of Bayreuth Germany IN2P3 Computing Center CNRS/IN2P3 Lyon-Villeurbanne France

ISBN: (纸本)9780769541570

Task scheduling is one of the most prominent problems in the era of parallel computing. We find scheduling algorithms in every domain of computer science, e.g., mapping multiprocessor tasks to clusters, mapping jobs to grid resources, or mapping fine-grained tasks to cores of multicore processors. Many tools exist that help understand or debug an application by presenting visual representations of a certain program run, e.g., visualizations of MPI traces. However, often developers want to get a global and abstract view of their schedules first. In this paper we introduce Jedule, a tool dedicated to visualize schedules of parallel applications. We demonstrate the effectiveness of Jedule by showing how it helped analyzing problems in several case studies. © 2010 IEEE.

关键词： Mapping

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Efficient routing in delay tolerant networks with correlated node mobility

Efficient routing in delay tolerant networks with correlated...

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2010 IEEE 7th International Conference on Mobile Adhoc and Sensor Systems, MASS 2010

作者： Bulut, Eyuphan Geyik, Sahin Cem Szymanski, Boleslaw K. Department of Computer Science Center for Pervasive Computing and Networking Rensselaer Polytechnic Institute 110 8th Street Troy NY 12180 United States

ISBN: (纸本)9781424474882

In a delay tolerant network (DTN), nodes are connected intermittently and the future node connections are mostly unknown. Since in these networks, a fully connected path from source to destination is unlikely to exist, message delivery relies on opportunistic routing. However, effective forwarding based on a limited knowledge of contact behavior of nodes is challenging. Most of the previous studies looked at only the pairwise node relations to decide routing. In contrast, in this paper, we analyze the correlation between the meetings of each node with other nodes and focus on the utilization of this correlation for efficient routing of messages. We introduce a new metric called conditional intermeeting time, which computes the average intermeeting time between two nodes relative to a meeting with a third node using only the local knowledge of the past contacts. Then, we show how we can utilize the proposed metric on the existing DTN routing protocols to improve their performance. For shortest-path based routing protocols in DTNs, we propose to route messages over conditional shortest paths in which the link cost between nodes are defined by conditional intermeeting times. Moreover, for metric-based forwarding protocols, we propose to use conditional intermeeting time as an additional delivery metric while making forwarding decisions of messages. Our trace-driven simulations on three different datasets show that the modified algorithms perform better than the original ones. ©2010 IEEE.

关键词： Delay tolerant networks

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A new Weighted Ensemble model for detecting DoS attack streams

A new Weighted Ensemble model for detecting DoS attack strea...

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2010 3rd IEEE/WIC/ACM International Conference on Web Intelligence and Intelligent Agent Technology - Workshops, WI-IAT 2010

作者： Yan, Jinghua Yun, Xiaochun Zhang, Peng Tan, Jianlong Guo, Li Department of Computer Science Beijing University of Post and Telecommunications Beijing China Information Security Center Institute of Computing Technology Chinese Academy of Sciences Beijing China

ISBN: (纸本)9780769541914

Recently, DoS (Denial of Service) detection has become more and more important in web security. In this paper, we argue that DoS attack can be taken as continuous data streams, and thus can be detected by using stream data mining methods. More specifically, we propose a new Weighted Ensemble learning model to detect the DoS attacks. The Weighted Ensemble model first trains base classifiers using different data classification algorithms (i.e., decision tree, SVMs, and Naive Bayes) on multiple successive data chunks, and then weights each base classifier according to its prediction accuracy on the up-to-date data. Experimental results on the benchmark KDDCUP'99 dataset demonstrate that our new Weighted Ensemble model is able to successfully detect DoS attacks. © 2010 IEEE.

关键词： Denial-of-service attack

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Conditional shortest path routing in delay tolerant networks

Conditional shortest path routing in delay tolerant networks

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2010 IEEE International Symposium on "A World of Wireless, Mobile and Multimedia Networks", WoWMoM 2010

ISBN: (纸本)9781424472659

Delay tolerant networks are characterized by the sporadic connectivity between their nodes and therefore the lack of stable end-to-end paths from source to destination. Since the future node connections are mostly unknown in these networks, opportunistic forwarding is used to deliver messages. However, making effective forwarding decisions using only the network characteristics (i.e. average intermeeting time between nodes) extracted from contact history is a challenging problem. Based on the observations about human mobility traces and the findings of previous work, we introduce a new metric called conditional intermeeting time, which computes the average intermeeting time between two nodes relative to a meeting with a third node using only the local knowledge of the past contacts. We then look at the effects of the proposed metric on the shortest path based routing designed for delay tolerant networks. We propose Conditional Shortest Path Routing (CSPR) protocol that routes the messages over conditional shortest paths in which the cost of links between nodes is defined by conditional intermeeting times rather than the conventional intermeeting times. Through trace-driven simulations, we demonstrate that CSPR achieves higher delivery rate and lower end-to-end delay compared to the shortest path based routing protocols that use the conventional intermeeting time as the link metric. ©2010 IEEE.

关键词： Delay tolerant networks

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Efficiently GPU-accelerating long kernel convolutions in 3-D DIRECT TOF PET reconstruction via a kernel decomposition scheme

Efficiently GPU-accelerating long kernel convolutions in 3-D...

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IEEE Symposium on Nuclear science (NSS/MIC)

作者： Sungsoo Ha Zhiyuan Zhang Klaus Mueller Samuel Matej Center of Visual Computing Computer Science Department Stony Brook University NY USA Department of Radiology University of Pennsylvania Philadelphia PA USA

The DIRECT approach for 3-D Time-of-Flight (TOF) PET reconstruction performs all iterative predictor-corrector operations directly in image space. A computational bottleneck here is the convolution with the long TOF (resolution) kernels. Accelerating this convolution operation using GPUs is very important especially for spatially variant resolution kernels, which cannot be efficiently implemented in the Fourier domain. The main challenge here is the memory cache performance at non-axis aligned directions. We devised a scheme that first re-samples the image into an axis-aligned orientation offering good memory coherence for the convolution operations. In order to maintain good accuracy, we carefully design the resampling and new convolution kernels to combine into the original TOF kernel. This paper demonstrates the validity, accuracy, and high speed-performance of our scheme for a comprehensive set of orientation angles. Future work will apply these cascaded kernels within a GPU-accelerated version of DIRECT.

关键词： Kernel Image reconstruction Graphics processing unit Acceleration Strontium Positron emission tomography Filtering theory

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Bayesian cognitive trust model based self-clustering algorithm for MANETs

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science China(Information sciences) 2010年第3期53卷 494-505页

作者： WANG Wei1,2,3 & ZENG GuoSun1,2,31department of computer science & Technology, Tongji University, Shanghai 200092, China 2Tongji Branch, National Engineering & Technology center of High Performance computer, Shanghai 200092, China 3Key Loboratory of Embedded System and Service computing, Ministry of Education, Shanghai 200092, China 1. Department of Computer Science & Technology Tongji University Shanghai 200092 China2. Tongji Branch National Engineering & Technology Center of High Performance Computer Shanghai 200092 China3. Key Loboratory of Embedded System and Service Computing Ministry of Education Shanghai 200092 China

With the introduction of mobile Ad hoc networks (MANETs), nodes are able to participate in a dynamic network which lacks an underlying infrastructure. Before two nodes agree to interact, they must trust that each will satisfy the security and privacy requirements of the other. In this paper, using the cognition inspired method from the brain informatics (BI), we present a novel approach to improving the search efficiency and scalability of MANETs by clustering nodes based on cognitive trust mechanism. The trust relationship is formed by evaluating the level of trust using Bayesian statistic analysis, and clusters can be formed and maintained autonomously by nodes with only partial knowledge. Simulation experiments show that each node can form and join proper clusters, which improve the interaction performance of the entire network. The essence of the underlying reason is analyzed through the theory of complex networks, revealing great scalability of this method.

关键词： trust model MANET self-clustering Bayesian method cognitive mobile

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Steganography in Chinese text

Steganography in Chinese text

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2010 International Conference on computer Application and System Modeling, ICCASM 2010

作者： Sun, Xinmei Meng, Peng Ye, Yun Hang, Liusheng HuaiBei Vocational and Technical College Huaibei Anhui 235000 China Department of Computer Science and Technology National High Performance Computing Center at Hefei Hefei 230027 China

ISBN: (纸本)9781424472369

Steganography is an important research direction of information security, which mainly research how to embed secret information into carriers, in order to achieve the objectives of secure communication. In this paper, a novel Chinese text steganography based on substitution of different forms Chinese characters is proposed. We propose two embedding methods named SSM and HESM. SSM simply substitute some characters to embed the hidden message, which has high embedding rate. In HESM, we first split the hidden message into segments with the same size, and then embed the hidden message segment by segment into the carrier text. The segment length can be adjusted according to the application requirements. The highest embedding rate of the our steganographic algorithm is about 2%. In addition, our algorithm don't change the content of the carrier text, and it can resist traditional attacking methods such as re-layout, and so on. © 2010 IEEE.

关键词： Steganography

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Two examples of GPGPU acceleration of memory-intensive algorithms

Two examples of GPGPU acceleration of memory-intensive algor...

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8th Eurographics Italian Chapter Conference 2010

作者： Marras, Stefano Mura, Claudio Gobbetti, Enrico Scateni, Riccardo Scopigno, Roberto University of Cagliari Dept. of Mathematics and Computer Science Italy Sardegna Ricerche DistrICT Lab. Italy CRS4 - Center for Advanced Studies Research and Development Sardinia Italy ISTI-CNR Visual Computing Lab. Italy

ISBN: (纸本)9783905673807

The advent of GPGPU technologies has allowed for sensible speed-ups in many high-dimension, memory-intensive computational problems. In this paper we demonstrate the effectiveness of such techniques by describing two applications of GPGPU computing to two different subfields of computer graphics, namely computer vision and mesh processing. In the first case, CUDA technology is employed to accelerate the computation of approximation of motion between two images, known also as optical flow. As for mesh processing, we exploit the massively-parallel architecture of CUDA devices to accelerate the face clustering procedure that is employed in many recent mesh segmentation algorithms. In both cases, the results obtained so far are presented and thoroughly discussed, along with the expected future development of the work. © The Eurographics Association 2010.

关键词： Parallel architectures

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Supervised reinforcement learning in discrete environment domains

Supervised reinforcement learning in discrete environment do...

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2010 2nd World Congress on Nature and Biologically Inspired computing, NaBIC 2010

作者： Jensen, Boris Ortiz-Arroyo, Daniel Cruz-Cortés, Nareli Rodríguez-Henríquez, Francisco Computational Intelligence and Security Lab. Department of Electronic Systems Aalborg University Denmark Center for Computing Research National Politechnique Institute Mexico Computer Science Department CINVESTAV-IPN Mexico

ISBN: (纸本)9781424473762

This paper describes a supervised reinforcement learning-based model for discrete environment domains. The model was tested within the domain of backgammon game. Our results show that a supervised actor-critic based learning model is capable of improving the initial performance and then eventually reach similar performance levels as those obtained by TD-Gammon, an artificial neural network player (ANN) trained by temporal differences. © 2010 IEEE.

关键词： Reinforcement learning

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