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.
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.
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.
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.
10931722
STAS: A Scalability Testing and Analysis System
Scalability is a crucial factor in performance evaluation and analysis of parallel and distributed systems. Much effort has been devoted to scalability research and several metrics are proposed. However, the lacking of an effective scalability analysis toolkit is still a major barrier for researchers to measure and analyze scalabilities. Isospeed scalability is a known metric and has been extended for general computing systems recently. This paper proposes an effective scalability testing and analysis system, called STAS, and presents its implementation with isospeed-e scalability metric. STAS provides the facility to conduct automated isospeed-e scalability measure and analysis. It reduces the burden for users to evaluate the performance of algorithms and systems. Experiments have been conducted to verify the design and implementation
28546328
Hypertool/2: A Parallel Incremental DAG Scheduling System
7318403
Numerical solutions of coupled Burgers equations with time- and space-fractional derivatives
In this paper, by introducing the fractional derivative in the sense of Caputo, the Adomian decomposition method is directly extended to study the coupled Burgers equations with time- and space-fractional derivatives. As a result, the realistic numerical solutions are obtained in a form of rapidly convergent series with easily computable components. The figures show the effectiveness and good accuracy of the proposed method.
20461063
The function cascade synchronization approach with uncertain parameters or not for hyperchaotic systems
The function cascade synchronization scheme for the hyperchaotic systems is proposed to make the states of two identical the hyperchaotic systems both with and without uncertain parameters asymptotically synchronized. Based on Lyapunov stability theory and the proposed scheme, the Lu system and Chen hyperchaotic system with and without uncertain parameters are chosen to achieve the function cascade synchronization simultaneously. Numerical simulations are used to verify the effectiveness and feasibility of the presented control scheme.
2275333
Risk probability estimating based on clustering
Ubiquitous computing environments are highly dynamic, with new unforeseen circumstances and constantly changing environments, which introduces new risks that cannot be assessed through traditional means of risk analysis. Mobile entities in a ubiquitous computing environment require the ability to perform an autonomous assessment of the risk incurred by a specific interaction with another entity in a given context. This assessment will allow a mobile entity to decide whether sufficient evidence exists to mitigate the risk and allow the interaction to proceed. Such evidence might include records of prior experiences, recommendations from a trusted entity or the reputation of the other entity. We propose a dynamic mechanism for estimating the risk probability of a certain interaction in a given environment using hybrid neural networks. We argue that traditional risk assessment models from the insurance industry do not directly apply to ubiquitous computing environments. Instead, we propose a dynamic mechanism for risk assessment, which is based on pattern matching, classification and prediction procedures. This mechanism uses an estimator of risk probability, which is based on the automatic clustering of defining features of the environment and the other entity, which helps avoid subjective judgments as much as possible.
40119866
A fault tolerant topology control in wireless sensor networks
Summary form only given. Topology control of wireless sensor networks (WSNs) is a key design challenge in terms of extending the lifetime of the network. The paper presents a fault tolerant topology control by adding necessary redundant nodes to the network's simple communication backbone, which results a higher vertex connectivity degree. It provides not only fault tolerance for unreliable node failure, but also support for upper level protocols. The paper also identifies several factors and synchronization methods which may affect the redundant node selection. A simulation study shows the improvement of network lifetime with a desired vertex connectivity degree.