2684214
Switch design to enable predictive multiplexed switching in multiprocessor networks
Predictive multiplexed switching is a new approach for building interconnection switches for high performance parallel systems. This approach advocates sacrificing some link bandwidth in return for more efficient network control and simpler connection management. The main idea is to depart from the traditional packet and wormhole switching in favor of row data communication over established communication pipes (connections). The overhead of this circuit switching approach can be justified when established connections are repeatedly used before they are torn down. For this, we use multiplexing to allow multiple connections to share the same resources (links and switches), thus avoiding tearing down connections prematurely. The connection establishment overhead is further reduced by exploring communication locality and predictability in applications that exhibit these properties. We present the design of an interconnection system which is based on multiplexed switching and which establishes connections either reactively, in response to dynamically generated requests, or proactively, in response to compiler or application directives. A communication prediction component may be supported to reduce the network control overhead in applications that exhibit communication locality and predictability. The design is evaluated using hardware design, synthesis, and cycle-accurate simulation. Comparison with more traditional switching paradigms shows the potential of our predictive multiplexed switching approach.
39463231
Entropy Based Evaluation of Communication Predictability in Parallel Applications
The performance of parallel computing applications is highly dependent on the efficiency of the underlying communication operations. While often characterized as dynamic, these communication operations frequently exhibit spatial and temporal locality as well as regularity in structure. These characteristics can be exploited to improve communication performance if the correct prediction model is selected to a suitable communication topology. In this paper we describe an entropy based methodology for quantifying and evaluating the success of different prediction models on actual workloads drawn from representative parallel benchmarks. We evaluate two different prediction criteria and combinations thereof: (1) Messages are partitioned by source node. (2) Use of a first order context model. We also describe the threshold for predication designed to largely avoid incorrect predication overheads. Our results show for simple predication models, even on highly dynamic benchmark applications, predictability can be improved by several orders of magnitude. In fact, using simple prediction techniques, over 75% of the communication volume is accurately predictable.
224355
Architecture design of grid GIS and its applications on image processing based on LAN
Computer technology and its relative subjects developed at very high speed in recent years, so is geo-information science, including Geographic Information System (GIS), remote sensing (RS) and global position system (GPS). But with the increase of data, many data cannot be used efficiently because of the tremendous amount of data and information and the difficulty of process and transfer through network. So how to develop internet technology to solve these problems becomes a difficult problem for current computer experts and geo-science experts. Fortunately, grid computing provides us the method to solve this problem effectively. Grid computing is a resources sharing model presented by computer experts to solve current network resources imbalance problem. Basing on the application of grid computing on geographical information system (GIS), this paper analyzes the weakness and problems of traditional GIS, and then gives the method to solve these problems with the technology provided by grid computing and web services. After analyzing the characteristic of grid computing this paper expatiates on current application status of grid computing on GIS and the problems it faces, with the technology of middleware, this paper presents the architecture of grid GIS and lists the techniques it needs. In conclusion, this paper concludes that the distributing middleware architecture based on grid geographic markup language (GridGML) and web services technique is a good solution to current problems, this architecture can also solve those problems such as effective resources sharing through internet and advancing international application's efficiency, at last we discuss its implementation process based on LAN.
39076655
Attribute-based Workload Characterization: An Initial Case Study
A vacuum control device comprises a casing in which are disposed at least two substantially parallel movable cups, the first cup being connected to the element to be displaced. Springs are interposed respectively between the two cups and between the second cup and a bottom end-wall of the casing. Two pipes or nipples connected to a vacuum source and to atmospheric pressure open into the casing respectively within the space located between the two cups and within the space located between the second cup and the casing end-wall.
13903434
GERT: an empirical reliability estimation and testing feedback tool
Software testing is an integral part of the software development process. Some software developers, particularly those who use the Extreme Programming test-driven development practice, continuously write automated tests to verify their code. We present a tool to complement the feedback loops created by continuous testing. The tool combines static source code metrics with dynamic test coverage for use throughout the development phase to predict a reliability estimate based on a linear combination of these values. Implemented as an open source plug-in to the Eclipse IDE, the tool facilitates the rapid transition between unit test case completions and testing feedback. The color-coded results highlight inadequate testing efforts as well as weaknesses in overall program structure. To illustrate the tool's efficacy, we share the results of its use on university software engineering course projects.
15164862
Experiences in initiating concurrency software research efforts
Multi-core CPUs are now common in modern computers. To get access to effectively an unlimited supply of compute resources, software programs that have been highly optimized to use a single CPU need to be converted where possible to use concurrency. We have initiated our concurrency software research for performance enhancement on a large-scale system with high throughput and low latency transactions. In this paper, we report our experience, experiments, and results in various aspects of concurrency design and programming, including multi-threaded prototypes, static and dynamic concurrency analysis, future techniques and trends, concurrency experiments, and concurrency design patterns. Based on the concurrency experiments, we achieved at least 80 percent overall performance increases as measured by transaction throughput. As a result, capital expenditures for large scale deployments can be significantly reduced.
18528231
In regression testing selection when source code is not available