645393
Performance of multiprocessor interconnection networks
A tutorial is provided on the performance evaluation of multiprocessor interconnection networks, to guide system designers in their design process. A classification of parallel/distributed systems is followed by a classification of multiprocessor interconnection networks. Basic terminology for performance evaluation is presented. The performance of crossbar interconnection networks, multistage interconnection networks, and multiple-bus systems is then addressed, and a comparison is made along them.<<ETX>>
229042
Introducing a New Cache Design into Vector Computers
Introduces an innovative cache design for vector computers, called prime-mapped cache. By utilizing the special properties of a Mersenne prime, the new design does not increase the critical path length of a processor, nor does it increase the cache access time as compared to existing cache organizations. The prime-mapped cache minimizes cache miss ratio caused by line interferences that have been shown to be critical for numerical applications by previous investigators. With negligibly additional hardware cost, significant performance gains are obtained by adding the proposed cache memory to an existing vector computer. The performance of the design is studied analytically, using a generic vector computation model. The analytical model is validated through extensive simulation experiments. A performance analysis for various vector access patterns shows that the prime-mapped cache performs significantly better than conventional cache organizations in the vector processing environment. The performance gain will increase with the increase of the speed gap between processors and memories. >
2566279
PRINS: Optimizing Performance of Reliable Internet Storages
Distributed storage systems employ replicas or erasure code to ensure high reliability and availability of data. Such replicas create great amount of network traffic that negatively impacts storage performance, particularly for distributed storage systems that are geographically dispersed over a wide area network (WAN). This paper presents a performance study of our new data replication methodology that minimizes network traffic for data replications. The idea is to replicate the parity of a data block upon each write operation instead of the data block itself. The data block will be recomputed back at the replica storage site upon receiving the parity. We name the new methodology PRINS (Parity Replication in IP-Network Storages). PRINS trades off highspeed computation for communication that is costly and more likely to be the performance bottleneck for distributed storages. By leveraging the parity computation that exists in common storage systems (RAID), our PRINS does not introduce additional overhead but dramatically reduces network traffic. We have implemented PRINS using iSCSI protocol over a TCP/IP network interconnecting a cluster of PCs as storage nodes. We carried out performance measurements on Oracle database, Postgres database, MySQL database, and Ext2 file system using TPC-C, TPC-W, and Micro benchmarks. Performance measurements show up to 2 orders of magnitudes bandwidth savings of PRINS compared to traditional replicas. A queueing network model is developed to further study network performance for large networks. It is shown that PRINS reduces response time of the distributed storage systems dramatically.
11786279
Effects of Arbitration Protocols on the Performance of Multiple-Bus Multiprocessors
36641724
A new and efficient FFT algorithm for distributed memory systems
This paper presents a new and optimal parallel implementation of multidimensional fast Fourier transform algorithm on distributed memory multiprocessors. Its optimality is obtained by minimizing the number of message passings necessary, at the cost of increase in message length. This distinctive feature of the new algorithm effectively utilizes the important architectural property of most of today's distributed memory multiprocessors-wormhole routing for interprocessor communications. By using the algebra of stride permutations and tenser products as a mathematical tool, we are able to derive and formulate an efficient data partition and communication scheme that reduces communication cost from O(N/sup 2/) required for the best known FFT to O(N) on an N/sup 2/-processor machine. Our data partition scheme is natural and efficient for solving discretized boundary value problems such as partial differential equations and finite element analysis. To evaluate the actual performance of our new algorithm in comparison with other existing parallel FFT algorithms, we have carried out implementation experiments on the Intel's Touchstone Delta machine.
78709
STICS: SCSI-to-IP cache for storage area networks
Abstract Data storage plays an essential role in today's fast-growing data-intensive network services. New standards and products emerge very rapidly for networked data storage. Given the mature Internet infrastructure, the overwhelming preference among the IT community recently is using IP for storage networking because of economy and convenience. iSCSI is one of the most recent standards that allow SCSI protocols to be carried out over IP networks. However, there are many disparities between SCSI and IP in terms of protocols, speeds, bandwidths, data unit sizes, and design considerations that prevent fast and efficient deployment of storage area network (SAN) over IP. This paper introduces SCSI-to-IP cache storage (STICS), a novel storage architecture that couples reliable and high-speed data caching with low-overhead conversion between SCSI and IP protocols. A STICS block consists of one or several storage devices and an intelligent processing unit with CPU and RAM. The storage devices are used to cache and store data while the intelligent processing unit carries out the caching algorithm, protocol conversion, and self-management functions. Through the efficient caching algorithm and localization of certain unnecessary protocol overheads, STICS can significantly improve performance, reliability, and scalability over current iSCSI systems. Furthermore, STICS can be used as a basic plug-and-play building block for data storage over IP. Analogous to “cache memory” invented several decades ago for bridging the speed gap between CPU and memory, STICS is the first-ever “cache storage” for bridging the gap between SCSI and IP making it possible to build an efficient SAN over IP. We have implemented software STICS prototype on Linux operating system. Numerical results using popular benchmarks such as vxbench, IOzone, PostMark, and EMC's trace have shown a dramatic performance gain over the current iSCSI implementation.
31114007
Cooperative Target Localization Method for Heterogeneous Sensor Networks
Based on the binary sensor model, a novel method for target localization in heterogeneous sensor networks is presented. With the binary information reported by nodes, target's position is locked into the intersection area of sensing areas of all nodes which detect the same target, and then the estimated position is computed by geometric means. The proposed method adapts to heterogeneous sensor networks, moreover, it can integrate with other target localization approaches easily. Simulation results demonstrate that, in sensor networks composed of the same type of sensors, our method lead to a decrease in average localization errors compared with the traditional method; in heterogeneous sensor networks, the method renders more accurate estimate of the target's location.
1988413
Test strategies for cost-sensitive decision trees
In medical diagnosis, doctors must often determine what medical tests (e.g., X-ray and blood tests) should be ordered for a patient to minimize the total cost of medical tests and misdiagnosis. In this paper, we design cost-sensitive machine learning algorithms to model this learning and diagnosis process. Medical tests are like attributes in machine learning whose values may be obtained at a cost (attribute cost), and misdiagnoses are like misclassifications which may also incur a cost (misclassification cost). We first propose a lazy decision tree learning algorithm that minimizes the sum of attribute costs and misclassification costs. Then, we design several novel "test strategies" that can request to obtain values of unknown attributes at a cost (similar to doctors' ordering of medical tests at a cost) in order to minimize the total cost for test examples (new patients). These test strategies correspond to different situations in real-world diagnoses. We empirically evaluate these test strategies, and show that they are effective and outperform previous methods. Our results can be readily applied to real-world diagnosis tasks. A case study on heart disease is given throughout the paper
7518182
Co-clustering based classification for out-of-domain documents
In many real world applications, labeled data are in short supply. It often happens that obtaining labeled data in a new domain is expensive and time consuming, while there may be plenty of labeled data from a related but different domain. Traditional machine learning is not able to cope well with learning across different domains. In this paper, we address this problem for a text-mining task, where the labeled data are under one distribution in one domain known as in-domain data, while the unlabeled data are under a related but different domain known as out-of-domain data. Our general goal is to learn from the in-domain and apply the learned knowledge to out-of-domain. We propose a co-clustering based classification (CoCC) algorithm to tackle this problem. Co-clustering is used as a bridge to propagate the class structure and knowledge from the in-domain to the out-of-domain. We present theoretical and empirical analysis to show that our algorithm is able to produce high quality classification results, even when the distributions between the two data are different. The experimental results show that our algorithm greatly improves the classification performance over the traditional learning algorithms.
3527694
A catalog of agent coordination patterns
This paper surveys the current state of the art in agentoriented software engineering, focusing on the area of coordinated multi-agent systems. In multi-agent systems, the interactions between the agents are crucial in determining the effectiveness of the system. Hence the adoption of an appropriate coordination mechanism is pivotal in the design of multi-agent system architectures. This paper does not focus on agent theory, rather on the development of an agent-oriented software engineering methodology, collaboration architectures and design patterns for collaboration. A catalog of coordination patterns inherent in multi-agent architectures is presented. Such patterns may be utilized in the architectural design stage of an agent-oriented software engineering methodology.
8767636
The Design and Implementation of a DCD Device Driver for Unix
Recent research results [1, 2] using simulation have demonstrated that Disk Caching Disk (DCD), a new disk I/O architecture, has the potential for drastically improving disk write performance besides its higher reliability than traditional disk systems. To validate whether DCD can live up to its promise in the real world environment, we have designed and implemented a DCD device driver for the Sun's Solaris operating system. Measured performance results are very promising. For metadata intensive benchmarks, our DCD driver outperforms the traditional system by a factor of 2-6 in terms of program execution speeds. The driver also guarantees file system integrity in the events of system crashes or failures. Moreover, unlike other approaches such as Log-structured File Systems or Soft Updates, the DCD driver is completely transparent to the OS. It does not require any changes to the OS or the on-disk data layout. As a result, it can be used as a "drop-in" replacement for the traditional disk device driver in an existing system to obtain immediate performance improvement. Our multi-layered device-driver approach significantly reduces the implementation overhead and improves portability.