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Design issues for a high-performance distributed shared memory on symmetrical multiprocessor clusters

Cluster computing 1999年第3期2卷 177-186页

作者： Roy, Sumit Chaudhary, Vipin Parallel and Distributed Computing Laboratory Department of Electrical and Computer Engineering Wayne State University Detroit USA

Clusters of Symmetrical Multiprocessors (SMPs) have recently become the norm for high-performance economical computing solutions. Multiple nodes in a cluster can be used for parallel programming using a message passing library. An alternate approach is to use a software distributed Shared Memory (DSM) to provide a view of shared memory to the application programmer. This paper describes Strings, a high performance distributed shared memory system designed for such SMP clusters. The distinguishing feature of this system is the use of a fully multi-threaded runtime system, using kernel level threads. Strings allows multiple application threads to be run on each node in a cluster. Since most modern UNIX systems can multiplex these threads on kernel level light weight processes, applications written using Strings can exploit multiple processors on a SMP machine. This paper describes some of the architectural details of the system and illustrates the performance improvements with benchmark programs from the SPLASH-2 suite, some computational kernels as well as a full fledged application. It is found that using multiple processes on SMP nodes provides good speedups only for a few of the programs. Multiple application threads can improve the performance in some cases, but other programs show a slowdown. If kernel threads are used additionally, the overall performance improves significantly in all programs tested. Other design decisions also have a beneficial impact, though to a lesser degree.

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parallel Algorithms for Deblurring of MR Images 13

Parallel Algorithms for Deblurring of MR Images

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13th International Conference on Computers and Their Applications, CATA 1998

作者： Menon, Padmanabhan Chaudhary, Vipin Pipe, James G. Parallel and Distributed Computing Laboratory Wayne State University DetroitMI48202 United States Department of Radiology Wayne State University DetroitMI48202 United States

ISBN: (纸本)9781618395443

This paper presents a parallelized algorithm for the deblurring of images obtained from Magnetic Resonance Imaging. Images generated by MRI may suffer a loss of clarity due to inhomogeneities in the magnetic field. One of the techniques for removing this blurring artifact is the demodulation of the data for each pixel of the image using the value of the magnetic field near that point in space. This method consists of acquiring a local field map, finding the best fit to a linear map and using it to deblur the image distortions due to local frequency variations. This is a very computation intensive operation and presents appreciable gains through parallelization. This paper presents the implementation of this algorithm using two popular message-passing platforms, PVM and MPI and discusses the pros and cons of each. A message-passing paradigm was chosen for parallelization since the target architecture is a network of workstations. Performance figures are presented for various problem and network sizes and future improvements are discussed. © 13th International Conference on Computers and Their Applications 1998, CATA 1998. All rights reserved.

关键词： Algorithms Image Processing Magnetic Resonance Imaging Message Passing MPI PVM

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HAF: a hybrid annotation framework based on expert knowledge and learning technique

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Science China(Information Sciences) 2022年第1期65卷 276-278页

作者： Zhixing LI Yue YU Tao WANG Gang YIN Xinjun MAO Huaimin WANG Key Laboratory of Parallel and Distributed Computing National University of Defense Technology College of Computer National University of Defense Technology

Dear editor,The increasing awareness of the potential value hidden in data has resulted in many data mining studies being conducted. In the domain of software engineering, for example, developers' behavioral data and code review data have been leveraged in social coding sites to automatically recommend relevant projects [1] and candidate reviewers [2, 3].

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Tinman: Eliminating confidential mobile data exposure with security oriented offloading 15

Tinman: Eliminating confidential mobile data exposure with s...

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10th European Conference on Computer Systems, EuroSys 2015

作者： Xia, Yubin Liu, Yutao Tan, Cheng Ma, Mingyang Guan, Haibing Zang, Binyu Chen, Haibo Shanghai Key Laboratory of Scalable Computing and Systems China Institute of Parallel and Distributed Systems Shanghai Jiao Tong University China Department of Computer Science Shanghai Jiao Tong University China

ISBN: (纸本)9781450332385

The wide adoption of smart devices has stimulated a fast shift of security-critical data from desktop to mobile devices. However, recurrent device theft and loss expose mobile devices to various security threats and even physical attacks. This paper presents TinMan, a system that protects confidential data such as web site password and credit card number (we use the term cor to represent these data, which is short for Confidential Record) from being leaked or abused even under device theft. TinMan separates accesses of cor from the rest of the functionalities of an app, by introducing a trusted node to store cor and offloading any code from a mobile device to the trusted node to access cor. This completely eliminates the exposure of cor on the mobile devices. The key challenges to TinMan include deciding when and how to efficiently and transparently offload execution;Tin-Man addresses these challenges with security-oriented offloading with a low-overhead tainting scheme called asymmetric tainting to track accesses to cor to trigger offloading, as well as transparent SSL session injection and TCP payload replacement to offload accesses to cor. We have implemented a prototype of TinMan based on Android and demonstrated how TinMan protects the information of user's bank account and credit card number without modifying the apps. Evaluation results also show that TinMan incurs only a small amount of performance and power overhead. Copyright © 2015 ACM.

关键词： Crime

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Grid Based Pervasive distributed Storage

Grid Based Pervasive Distributed Storage

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International Symposium on Wireless Pervasive computing (ISWPC)

作者： Diego Arias John Sanabria Wilson Rivera Parallel and Distributed Computing Laboratory University of Puerto Rico Mayaguez Puerto Rico

This paper describes a tool that implements a set of services to manipulate and store data from a sensor network in a transparent way to end users. A major requirement of this system is data availability and reliability. Consequently, we have implemented a replication schema based on the information dispersal algorithm (IDA). Preliminary results show that the IDA based replication provides better reliability and less storage spending than traditional replication. The storage scheme has been deployed on top of a Globus based infrastructure

关键词： Network servers Galois fields Polynomials Large-scale systems Sensor systems Wireless sensor networks Secure storage distributed computing Laboratories Sensor phenomena and characterization

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Unique sets oriented partitioning of nested loops with non-uniform dependences

Unique sets oriented partitioning of nested loops with non-u...

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International Conference on parallel Processing (ICPP)

作者： Jialin Ju V. Chaudhary Parallel and Distributed Computing Laboratory Wayne State University Detroit MI USA

Although many methods exist for nested loop partitioning, most of them perform poorly when parallelizing loops with non-uniform dependences. This paper addresses the issue of parallelizing nested loops with non-uniform dependences. The approach is based on convex hull theory, which has adequate information to handle non-uniform dependences. We introduce the concept of Complete Dependence Convex Hull, unique head and tail sets and abstract the dependence information into these sets. These sets form the basis of the iteration space partitions. The properties of the unique head and tail sets are derived using convex hull theory. Depending on the relative placement of these unique sets, the partitioning problem is grouped into several cases. Several partitioning schemes are also suggested for implementing the technique. Preliminary implementation results of the scheme on the Cray J916 and comparison with other schemes show a dramatic improvement in performance.

关键词： Tail parallel processing distributed computing Laboratories Sparse matrices Contracts Processor scheduling Indium tin oxide Tiles

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Evaluation of cluster interconnects for a distributed shared memory

Evaluation of cluster interconnects for a distributed shared...

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IEEE International Conference on Performance, computing and Communications (IPCCC)

作者： S. Roy V. Chaudhary Parallel and Distributed Computing Laboratory Wayne State University Detroit MI USA

Clusters of Symmetrical Multiprocessors (SMPs) have recently become popular as low-cost, high-performance computing solutions. The type of interconnection hardware used in these clusters can become a deciding factor in their overall performance. This paper evaluates the performance of three different communication systems, 10 Mbps Ethernet, 100 Mbps FastEthernet and 155 Mbps ATM, using a multithreaded distributed Shared Memory system, Strings. The raw performance of each network is first measured using netperf. Ten different applications are then used for performance evaluation, including programs from the SPLASH-2 benchmarks, a medical computing application, and some computational kernels. It is found that half of the programs tested are not significantly affected by changes in the bandwidth. Though the ATM network provides the highest overall bandwidth, the remaining applications show that the increase in latency compared to FastEthernet prevents any performance improvement. On the other hand, applications that require only moderately high bandwidths perform substantially better with FastEthernet.

关键词： Bandwidth distributed computing Programming profession Ethernet networks Asynchronous transfer mode Benchmark testing Biomedical computing Kernel Delay Microprocessors

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A new metric for processor allocation schemes in multiprocessor systems

A new metric for processor allocation schemes in multiproces...

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IEEE International Conference on Performance, computing and Communications (IPCCC)

作者： S. Roy V. Chaudhary Parallel and Distributed Computing Laboratory Wayne State University Detroit MI USA

Recently a number of scalable interconnection networks for connecting multiple processors have been proposed. Though these networks differ in their properties such as bisection bandwidth, node degree, network diameter, and average diameter, there is one common problem that must be addressed by their designers. It should be possible to subdivide the set of processors such that the subset forms a smaller version of the underlying topology. This task is termed as Processor Allocation in general and Subcube allocation for Hypercubes. Various techniques appear in literature, including tree collapsing, free-list based approaches and others. A common metric for evaluating a scheme is the extent to which it can recognize all the possible sub-graphs in a particular network. In this paper are show that recognizability alone is a poor yardstick for predicting the performance of a processor allocation scheme. We introduce the ideas of Search Space and Impact Sets and propose a new, more pragmatic metric to measure the efficiencies of an allocation scheme. We evaluate this metric for a simple buddy strategy and a hypothetical exhaustive scheme for two popular interconnection networks, the Star Graph and the k-ary-n-cube. We support our results by simulation experiments and conclude that a scheme with higher recognizability is unlikely to justify the associated increase in complexity and storage requirements.

关键词： Hypercubes Multiprocessor interconnection networks Multiprocessing systems Operating systems Intelligent networks distributed computing Laboratories Joining processes Bandwidth Topology

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VButton: Practical attestation of user-driven operations in mobile apps 18

VButton: Practical attestation of user-driven operations in ...

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16th ACM International Conference on Mobile Systems, Applications, and Services,MobiSys 2018

作者： Li, Wenhao Luo, Shiyu Sun, Zhichuang Xia, Yubin Lu, Long Chen, Haibo Zang, Binyu Guan, Haibing Institute of Parallel and Distributed Systems Shanghai Jiao Tong University China Shanghai Key Laboratory of Scalable Computing and Systems Shanghai Jiao Tong University China Northeastern University United States

ISBN: (纸本)9781450357203

More and more malicious apps and mobile rootkits are found to perform sensitive operations on behalf of legitimate users without their awareness. Malware does so by either forging user inputs or tricking users into making unintended requests to online service providers. Such malware is hard to detect and generates large revenues for cybercriminals, which is often used for committing ad/click frauds, faking reviews/ratings, promoting people or business on social networks, etc. We find that this class of malware is possible due to the lack of practical and robust means for service providers to verify the authenticity of user-driven operations (i.e., operations supposed to be performed, or explicitly confirmed, by a user). We design and build the VButton system to fill this void. Our system introduces a class of attestation-enabled app UI widgets (called VButton UI). Developers can easily integrate VButton UI in their apps to allow service providers to verify that a user-driven operation triggered by a VButton UI is indeed initiated and intended by a real user. Our system contains an on-device Manager, and a server-side Verifier. Leveraging ARM TrustZone, our system can attest operation authenticity even in the presence of a compromised OS. We have implemented the VButton system on an ARM development board as well as a commercial off-the-shelf smartphone. The evaluation results show that the system incurs negligible overhead. © 2018 Association for computing Machinery.

关键词： Malware

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OMP: a RISC-based multiprocessor using orthogonal-access memories and multiple spanning buses 90

OMP: a RISC-based multiprocessor using orthogonal-access mem...

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Proceedings of the 4th international conference on Supercomputing

作者： K. Hwang M. Dubois D. K. Panda S. Rao S. Shang A. Uresin W. Mao H. Nair M. Lytwyn F. Hsieh J. Liu S. Mehrotra C. M. Cheng Laboratory for Parallel and Distributed Computing University of Southern California Los Angeles CA

ISBN: (纸本)9780897913690

This paper presents the architectural design and RISC based implementation of a prototype supercomputer, namely the Orthogonal MultiProcessor (OMP). The OMP system is constructed with 16 Intel 1860 RISC microprocessors and 256 parallel memory modules, which are 2-D interleaved and orthogonally accessed using custom-designed spanning buses. The architectural design has been validated by a CSIM-based multiprocessor simulator. The design choices are based on worst-case delay analysis and simulation validation. The current OMP prototype chooses a 2-dimensional memory architecture, mainly for image processing, computer vision, and neural network simulation applications. The 16-processor OMP prototype is targeted to achieve a peak performance of 400 RISC integer MIPS or a maximum of 640 Mflops. This paper presents the architectural design of the OMP prototype at system and PC board levels. We are presently entering the fabrication stage of all the PC boards. The system is expected to become operational in late 1991 and benchmarking results will be available in 1992. Only hardware design features are reported here. Software and simulation results are reported elsewhere.

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