14028105
Scalability of heterogeneous computing
Scalability is a key factor of the design of distributed systems and parallel algorithms and machines. However, conventional scalabilities are designed for homogeneous parallel processing. There is no suitable and commonly accepted definition of scalability metric for heterogeneous systems. Isospeed scalability is a well-defined metric for homogeneous computing. This study extends the isospeed scalability metric to general heterogeneous computing systems. The proposed isospeed-efficiency metric is suitable for both homogeneous and heterogeneous computing. Through theoretical analysis, we derive methodologies of scalability measurement and prediction for heterogeneous systems. Experimental results verify the analytical results and confirm that the proposed isospeed-efficiency scalability works well in both homogeneous and heterogeneous environments.
61649411
Parallel I/O prefetching using MPI file caching and I/O signatures
Parallel I/O prefetching is considered to be effective in improving I/O performance. However, the effectiveness depends on determining patterns among future I/O accesses swiftly and fetching data in time, which is difficult to achieve in general. In this study, we propose an I/O signature-based prefetching strategy. The idea is to use a predetermined I/O signature of an application to guide prefetching. To put this idea to work, we first derived a classification of patterns and introduced a simple and effective signature notation to represent patterns. We then developed a toolkit to trace and generate I/O signatures automatically. Finally, we designed and implemented a thread-based client-side collective prefetching cache layer for MPI-IO library to support prefetching. A prefetching thread reads I/O signatures of an application and adjusts them by observing I/O accesses at runtime. Experimental results show that the proposed prefetching method improves I/O performance significantly for applications with complex patterns.
14925300
A Taxonomy of Data Prefetching Mechanisms
Data prefetching has been considered an effective way to mask data access latency caused by cache misses and to bridge the performance gap between processor and memory. With hardware and/or software support, data prefetching brings data closer to a processor before it is actually needed. Many prefetching techniques have been proposed in the last few years to reduce data access latency by taking advantage of multi-core architectures. In this paper, we propose a taxonomy that classifies various design concerns in developing a prefetching strategy. We discuss various prefetching strategies and issues that have to be considered in designing a prefetching strategy for multi-core processors.
43007315
The impact of smart disks and spatial reuse property on RAID-5 storage systems
RAID storage systems using SCSI and traditional disk drives cannot meet the growing demand of new I/O intensive applications. New technologies such as smart disks and SSA are being proposed to improve the performance, scalability, and reliability of RAID systems. The objective of this work is to investigate the impact of smart disks and SSA's spatial reuse property on the performance of RAID-5 storage systems. In order to perform this work, we have enhanced CMU's RAIDframe simulator so that it accurately models the overhead of current SCSI and SSA protocols, and we have created smart disk models which include on-drive XOR logic and on-drive caches. We observe that neither smart disks alone nor spatial reuse property alone has much impact on RAID system performance. However, if smart disks and spatial reuse property are properly used in combination, RAID-5 system performance and scalability can be further enhanced. In particular, we propose a parity caching approach to improve the performance of small writes.
12297104
CoStore: a reliable and highly available storage system using clusters
The CoStore cluster architecture is proposed to construct a reliable and highly available storage system. A prototype CoStore was implemented and its performance was measured with the cluster being mirrored in various network environments. The preliminary results demonstrate that there is little impact on performance if the cluster is mirrored in efficient campus network environments with high bandwidth and low latency. As a result the CoStore architecture considerably reinforces a storage system's preparedness for disaster recovery without sacrificing performance.
417212
Taxonomy of Data Prefetching for Multicore Processors
Data prefetching is an effective data access latency hiding technique to mask the CPU stall caused by cache misses and to bridge the performance gap between processor and memory. With hardware and/or software support, data prefetching brings data closer to a processor before it is actually needed. Many prefetching techniques have been developed for single-core processors. Recent developments in processor technology have brought multicore processors into mainstream. While some of the single-core prefetching techniques are directly applicable to multicore processors, numerous novel strategies have been proposed in the past few years to take advantage of multiple cores. This paper aims to provide a comprehensive review of the state-of-the-art prefetching techniques, and proposes a taxonomy that classifies various design concerns in developing a prefetching strategy, especially for multicore processors. We compare various existing methods through analysis as well.
37797167
A wide dynamic range CMOS image sensor with pulse-frequency-modulation and in-pixel amplification
This paper briefly examines the pros and cons of CMOS pulse-frequency-modulation (PFM) digital pixel sensors. A pulse-frequency-modulation digital pixel sensor with in-pixel amplification is proposed to improve the resolution of the pixel sensor at low illumination. The proposed PFM digital pixel sensor offers the characteristics of a reduced integration time when the level of illumination is low with the fill factor comparable to that of PFM digital pixel sensors without in-pixel amplification. The proposed digital image sensor has been designed in [email protected] 1.8V CMOS technology and validated using Spectre from Cadence Design Systems with BSIM3V3 device models. Simulation results demonstrate that the dynamic range of the proposed PFM digital pixel sensor with in-pixel amplification is 20dB larger as compared with that of PFM digital pixel sensors without in-pixel amplification. The increased dynamic range is obtained in the low illumination condition where PFM digital pixel sensors without in-pixel amplification cease the operation due to the low photo current.
40372820
Mining circumstance-oriented association rules using singular value decomposition technique
Association rule has evolved from the primitive form of single dimension intratransaction to the form of multi-dimension intertransaction. The challenge for mining multi-dimension intertransaction rules is the formidable search space. Researchers have proposed various methods to handle this problem, such as restricting the number of dimensions, confining search space in a small window, etc. These methods unavoidably have negative impact on mining result and they are less effective when the number of dimensions and the length of rule are really large. Moreover, all these methods are derived from the a priori algorithm and have common weaknesses: time consuming and redundancy caused by the iterative nature of the a priori algorithm. To approach this problem from a different angle, we propose to use the singular value decomposition technique (SVD). With SVD, the multi-dimension intertransaction rules can be easily identified.
14185433
Affective Computing Model Based on Rough Fuzzy Sets
In human affective research, the fuzziness and roughness of the affective computing is the chief difficult. This paper builds a novel affective model based on rough fuzzy sets for the first time and presents a serial of static description results, which effectively solve the fuzzy and rough problems in affective computing. The model can realize the precision control of affective computing conveniently. Finally, the simulation shows that the results of the model for the affective static description are reasonable. This paper extends the results in (Yong Chen and Tong He, 2005) and lays the foundation of the affective computing in depth
20937522
Generalized Riccati equation expansion method and its application to the (3 + 1)-dimensional Jumbo-Miwa equation
Based on the computerized symbolic system Maple and a Riccati equation, a generalized Riccati equation expansion method for constructing soliton-like solutions of non-linear evolution equations (NEEs) is presented by a new general ansatz. The proposed method is more powerful than most of the existing tanh methods, the extended tanh-function method, the modified extended tanh-function method and generalized hyperbolic-function method. By use of the method, we not only can successfully recover the previously known formal solutions but also construct new and more general formal solutions for some NEEs. Making use of the method, we study the the (3+1)-dimensional Jumbo-Miwa equation and obtain rich new families of the exact solutions, including the non-travelling wave and coefficient functions' soliton-like solutions, singular soliton-like solutions, periodic form solutions.
21338568
Research on Risk Probability Estimating Using Fuzzy Clustering for Dynamic Security Assessment
Effective network security management requires assessment of inherently uncertain events and circumstances dynamically. This paper addresses the problems of risk probability assessment and presents an alternative approach for estimating probability of security risk associated with some interaction in ubiquitous computing. A risk probability assessment formula is proposed, and an estimating model adopting the Fuzzy C-Means clustering algorithm is presented. An experiment based on DARPA intrusion detection evaluation data is given to support the suggested approach and demonstrate the feasibility and suitability for use. The practices indicate that fuzzy clustering technique provides concepts and theoretical results that are valuable in formulating and solving problems in dynamic security assessment.