the spread of virtual environments is setting forth a new set of challenges in the management of system resources for guaranteeing Quality of Service (QoS). this paper describes an implementation of end-user QoS contr...
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ISBN:
(纸本)0769505686
the spread of virtual environments is setting forth a new set of challenges in the management of system resources for guaranteeing Quality of Service (QoS). this paper describes an implementation of end-user QoS control to a distributed Virtual Environment Platform DVECOM [Choukair00]. In particular, we describe how to guarantee mandatory properties such as synchronization and consistency and how to reduce the impact on the application in case of sudden overload in the system and how we master this degradation to guarantee a smooth degradation according to the end user requirements. this representation degradation is driven by the user choices and profile selected through the offered rendering strategy API. We also present our evaluation of the QoS implementation, describing some interesting results we achieved in a simulation of a collaborative work in the system.
Many image processing algorithms have a very high execution time if only a processor is used for processing them. Using a SIMD parallel structure for its execution could reduce this time. this is particularly importan...
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ISBN:
(纸本)0769522556
Many image processing algorithms have a very high execution time if only a processor is used for processing them. Using a SIMD parallel structure for its execution could reduce this time. this is particularly important in the case of algorithms that must be processed in real time. the use of networks of PCs is an appealing solution that besides its low cost, takes advantage from both, the high speed of actual interconnection networks, and the high-performance of PCs. In this paper we present a model that explicitly considers system parameters, network parameters, and application parameters. So, the speed and communication model of the considered network, the workstations and PCs computing power, the per-pixel computational cost of the algorithms (that can be constant or variable), and a variable number of computers have been considered.
the long lifecycles of many scientific applications tend to surpass multiple generations of Grid technologies opening an increasing gap developers need to bridge. Automatic adaptation and migration of software to newe...
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ISBN:
(纸本)9781424403431
the long lifecycles of many scientific applications tend to surpass multiple generations of Grid technologies opening an increasing gap developers need to bridge. Automatic adaptation and migration of software to newer environments remains therefore as interesting research question. Most existing state-of-the-art solutions are Grid middleware services that execute programs based on provided descriptions forcing clients to use a generic and non-problem-centric interface. this short paper outlines the Otho Toolkit for synthesis of Grid application wrapper services based on specifications of scientific legacy programs. the generated output are service source codes that are either automatically built and packaged into a ready-to-deploy services or taken by developers for manual refinement. the services are customised and tailor-made for a specific application, service hosting environment and computational infrastructure. To increase their benefit they can be enhanced with supplemental functionality such as security credential management or filestaging. We applied the Otho Toolkit recursively to itself to synthesise a sophisticated Factory service that creates application-specific Grid services on-demand.
Python has been adopted as programming language by a large number of scientific communities. Additionally to the easy programming interface, the large number of libraries and modules that have been made available by a...
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ISBN:
(纸本)9781450351249
Python has been adopted as programming language by a large number of scientific communities. Additionally to the easy programming interface, the large number of libraries and modules that have been made available by a large number of contributors, have taken this language to the top of the list of the most popular programming languages in scientific applications. However, one main drawback of Python is the lack of support for concurrency or parallelism. PyCOMPSs is a proved approach to support task-based parallelism in Python that enables applications to be executed in parallel in distributed computing platforms. this paper presents PyCOMPSs and how it has been tailored to execute tasks in heterogeneous and multi-threaded environments. We present an approach to combine the task-level parallelism provided by PyCOMPSs withthe thread-level parallelism provided by MKL. Performance and behavioral results in distributed computing heterogeneous clusters show the benefits and capabilities of PyCOMPSs in both HPC and Big Data infrastructures.
this paper studies relations between the parallel random access machine (PRAM) model, and the reconfigurable mesh (RMESH) model, by providing mutual simulations between the models. We present an algorithm simulating o...
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this paper studies relations between the parallel random access machine (PRAM) model, and the reconfigurable mesh (RMESH) model, by providing mutual simulations between the models. We present an algorithm simulating one step of an (n lg lg n)-processor CRCW PRAM on an n × n RMESH with delay O(lg lg n) with high probability. We use our PRAM simulation to obtain the first efficient self-simulation algorithm of an RMESH with general switches: An algorithm running on an n × n RMESH is simulated on a p × p RMESH with delay O((n/p)2 + lg n lg lg p) with high probability, which is optimal for all p &le n/√lg n lg lg n. Finally, we consider the simulation of RMESH on the PRAM. We show that a 2 × n RMESH can be optimally simulated on a CRCW PRAM in Θ(α(n)) time, where α(·) is the slow-growing inverse Ackermann function. In contrast, a PRAM with polynomial number of processors cannot simulate the 3 × n RMESH in less than Ω(lg n/lg lg n) expected time.
the proceedings contain 110 papers. the topics discussed include: a rate control protocol for high speed streaming video;collaboration between security devices toward improving network defense;trust mechanism in distr...
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ISBN:
(纸本)9780769531311
the proceedings contain 110 papers. the topics discussed include: a rate control protocol for high speed streaming video;collaboration between security devices toward improving network defense;trust mechanism in distributed access control model of P2P networks;convergence analysis of Jacobi iterative method using logarithmic number system;effective RTL method to develop on-line self-test routine for the processors using the wavelet transform;comparison between new quantum approaches for finding the minimum or the maximum of an unsorted set of integers;evaluation on quantum computation and classic parallel approaches for finding estimation of the length of shortest path in a weighted graph;a real-time interactive visualization system for DNS amplification attack challenges;radix plus length based insert sort;and an integer linear programming approach for dedicated machine constraint.
Device model evaluation, an essential part of a circuit simulator, is a compute-intensive task. A multiprocessor-based circuit simulator that ignores the parallelization of model equation formulation (LOAD), and just ...
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ISBN:
(纸本)0818649909
Device model evaluation, an essential part of a circuit simulator, is a compute-intensive task. A multiprocessor-based circuit simulator that ignores the parallelization of model equation formulation (LOAD), and just parallelizes the solution (SOLVE) of the equations will seriously degrade the simulation performance. this paper describes methods of parallelizing the LOAD part of a circuit simulator on PACE (parallel Architecture for Circuit Evaluation) a distributed memory multiprocessor designed at AT&T Bell Laboratories. this is integrated withthe parallel SOLVE algorithms given in our earlier work. Load balancing and minimization of interprocessor communication are used as the primary objectives of the parallel LOAD heuristics studied. Performance results, using the prototype PACE system, on benchmark circuits show the feasibility of our approach.
In this paper we present the case study of an application of a parallelsimulation optimization deployed in an on-premises Cloud. the compute-intensive application uses a Master/Worker model, supporting communication ...
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ISBN:
(纸本)9781605588476
In this paper we present the case study of an application of a parallelsimulation optimization deployed in an on-premises Cloud. the compute-intensive application uses a Master/Worker model, supporting communication over both Java RMI and Globus Grid Services between the nodes. the Master deploys Workers over an Eucalyptus Cloud using the Nimbus Context Broker for just-in-time configuration and runtime Worker discovery. the computational performance of the Workers under different communication mechanisms and deployment scenarios is presented in an attempt to evaluate the use of Virtual Machines in a Cloud as a tool to achieve application scaling. the deployment of this particular application was crafted to support on-the-fly addition of working nodes. the case study suggests a deployment pattern that shapes some requirements and considerations of a scalable Globus-driven Platform as a Service Cloud.
Social interaction is a key driving force behind any team activity. Real time closely coupled interaction, where we quickly see the effect of our actions on others, is an important feature of social interaction. For e...
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ISBN:
(纸本)0769520367
Social interaction is a key driving force behind any team activity. Real time closely coupled interaction, where we quickly see the effect of our actions on others, is an important feature of social interaction. For example, smiling and returning a smile, shaking hands and passing a gift or business card are some of the most important interactions in the real world. Collaborative Virtual Environments (CVE) offer the potential for social interaction between geographically distributed groups. Closely coupled interaction is, however, very difficult in present CVE systems. this is because this medium lags behind real world communication in terms of representation, consistency and responsiveness. this paper takes a psychological perspective, describing how the primary forms of human communication in the real world map to those in the virtual. We discuss how each form of communication relates to the feeling of co-presence, giving real examples of behaviour observed an example application, the virtual gazebo. We present detailed results from user evaluation, focusing on the perceived importance of these influences on collaboration.
the proceedings contain 17 papers. the topics discussed include: challenges of evolving sequential to parallel code: an exploratory review;an editing-operation replayer with highlights supporting investigation of prog...
ISBN:
(纸本)9781450308489
the proceedings contain 17 papers. the topics discussed include: challenges of evolving sequential to parallel code: an exploratory review;an editing-operation replayer with highlights supporting investigation of program modifications;problem-solution mapping for forward and reengineering on architectural level;challenges in model-based evolution and merging of access control policies;an agent-based framework for distributed collaborative model evolution;run-time phenomena in dynamic software updating: causes and effects;requirements evolution drives software evolution;towards a benchmark for traceability;towards a classification of logical dependencies origins: a case study;a taxonomy for software change impact analysis;using the gini coefficient for bug prediction in eclipse;are the classes that use exceptions defect prone?;and causes of premature aging during software development: an observational study.
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