this paper presents a concept called virtual clusters (VCs) to allocate resources for an application from a computing utility with a geographically distributed resource base. the VC creation process is modeled as a fa...
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this paper presents a concept called virtual clusters (VCs) to allocate resources for an application from a computing utility with a geographically distributed resource base. the VC creation process is modeled as a facility location problem and an efficient heuristic is devised to solve it. We extend the model to include an "overload partition" to a VC such that demand surges can be efficiently handled. Extensive simulations have been conducted to examine the performance of VCs under different scenarios and to compare it with a fully dynamic scheme called the Service Grid. the results indicate that VC is more cost-effective and robust than Service Grid.
Program analysis is an important activity to evaluate and subsequently improve the quality of software. Many different visualization tools offer more or less sophisticated functionality for this task. However, the vis...
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Program analysis is an important activity to evaluate and subsequently improve the quality of software. Many different visualization tools offer more or less sophisticated functionality for this task. However, the visual capabilities of the tool are usually pre-defined by the tool developers' intentions or are only marginally adaptable to the user's needs. On contrary, the VisWiz tool offers a means of providing user-defined visualization for analysis of parallel and distributed programs. By configuring the mapping of observed events and their relations using a XML configuration file, users are able to develop specialized graphical displays, which better suit their expectations and improve program comprehension. Examples of VisWiz are given for debugging, performance tuning, and runtime monitoring of parallel and distributed programs.
On parallelsystems, jobs that request a large fraction of the maximum resources available on the system may incur poor wait time. this paper evaluates whether giving a reservation to every waiting job can improve lar...
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On parallelsystems, jobs that request a large fraction of the maximum resources available on the system may incur poor wait time. this paper evaluates whether giving a reservation to every waiting job can improve large jobs without significantly degrading the performance of other jobs. Using a wide range of workloads, including more recent workloads than SP2 workloads, and a more complete set of performance measures than in previous studies, we provide new observations of potential benefit and problem of reservation policies that give all jobs a reservation.
As the complexity of chip designs increase, simulation time also increases. Unit and variable delay simulation takes the most simulation time in IC design process;however, parallel processing performs inefficiently du...
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As the complexity of chip designs increase, simulation time also increases. Unit and variable delay simulation takes the most simulation time in IC design process;however, parallel processing performs inefficiently due to large amount of synchronization. In this paper, techniques to reduce the number of synchronization points in synchronous designs are proposed, and a partitioner to partition designs along flip-flop boundaries is also proposed so that these techniques can be employed on real designs.
this paper introduces invasive computing, a new paradigm for programming parallel architectures. the goals are to enable the development and execution of resource aware programs that can dynamically allocate and free ...
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ISBN:
(纸本)9780889868649
this paper introduces invasive computing, a new paradigm for programming parallel architectures. the goals are to enable the development and execution of resource aware programs that can dynamically allocate and free new resources in phases with more parallelism. To allocate more resources, applications use the invade operation and to free them the retreat. the research is conducted within the framework of the Transregional Collaborative Research Centre 89 funded by the German Science Foundation.
We consider a distributed computer system in Wardrop equilibrium, i.e., situations where no user can reduce its own response time by unilaterally choosing another path, if all the other users retain their present path...
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ISBN:
(纸本)0889865701
We consider a distributed computer system in Wardrop equilibrium, i.e., situations where no user can reduce its own response time by unilaterally choosing another path, if all the other users retain their present paths. the Braess paradox is a famous example of paradoxical cases where adding capacity to a network degrades the performance of all users. this study examines numerically some examples around the Braess-like paradox in a distributed computer system. We found that Braess's paradox can occur, namely in equilibrium the mean job response time in the network after adding a communication line for the sharing of jobs between nodes, for some system parameter setting, can be greater than the mean job response time in the network before adding the communication line. Indeed, two different types of paradox called weak and strong paradox have been characterized. In the range of parameter values examined, the worst case ratio of performance degradation obtained in the examined network model is about 75% and 65% for the cases of weak and strong paradox respectively.
In this paper, we provide an "Improved Channel Aware QoS Scheduling Architecture for WiMAX Base Stations". In this scheme, we provide intelligence to the classifier by having feedback from the compensation b...
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ISBN:
(纸本)9780889867741
In this paper, we provide an "Improved Channel Aware QoS Scheduling Architecture for WiMAX Base Stations". In this scheme, we provide intelligence to the classifier by having feedback from the compensation block. We capitalize on the design of WiMAX, which differentiates connections with separate connection IDs and classifies traffic, based on a class-based approach. We propose a design in which the Classifier, in order to provide excellent QoS, admits frames with only those CIDs that can be serviced without any significant delay to the real time voice and video applications, thus improving the overall QoS. In other words, it rejects a packet having a CID which is experiencing bad channel quality and allows unmarked CIDs to utilize the channel at its maximum efficiency.
In parallel Discrete Event Simulation (PDES), the simulation model is partitioned into a set of distinct Logical Processes (LPs) which are allowed to concurrently execute simulation events. In this work we present an ...
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ISBN:
(纸本)9781467323703;9781467323727
In parallel Discrete Event Simulation (PDES), the simulation model is partitioned into a set of distinct Logical Processes (LPs) which are allowed to concurrently execute simulation events. In this work we present an innovative approach to load-sharing on multi-core/multiprocessor machines, targeted at the optimistic PDES paradigm, where LPs are speculatively allowed to process simulation events with no preventive verification of causal consistency, and actual consistency violations (if any) are recovered via rollback techniques. In our approach, each simulation kernel instance, in charge of hosting and executing a specific set of LPs, runs a set of worker threads, which can be dynamically activated/deactivated on the basis of a distributed algorithm. the latter relies in turn on an analytical model that provides indications on how to reassign processor/core usage across the kernels in order to handle the simulation workload as efficiently as possible. We also present a real implementation of our load-sharing architecture within the ROme OpTimistic Simulator (ROOT-Sim), namely an open-source C-based simulation platform implemented according to the PDES paradigm and the optimistic synchronization approach. Experimental results for an assessment of the validity of our proposal are presented as well.
Recently, there have been several developments in the scientific community to model and solve complex optimization problems by employing natural metaphors. In some cases, due to their distributed schema, these algorit...
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ISBN:
(纸本)9780769543284
Recently, there have been several developments in the scientific community to model and solve complex optimization problems by employing natural metaphors. In some cases, due to their distributed schema, these algorithms can be adapted to distributedcomputing environments. A distributed and asynchronous bees (DAB) grid-based approach is here used to optimise the magnetic configuration in order to reduce the neoclassical transport of particles in a nuclear fusion device. Large-scale problems (as several plasma physics can be classified) present open challenges that need a large computing capacity to be solved. thus, the use of large distributed infrastructures is mandatory in many of these problems. the use of grid computing offers a new paradigm where the distributed nature of foraging can be reproduced and applied to complex optimisation problems.
In engineering applications often real-valued performance functions must be optimized. If the performance function is discontinuous, there exist no derivations with respect to the parameters that should be optimized. ...
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ISBN:
(纸本)9780889867741
In engineering applications often real-valued performance functions must be optimized. If the performance function is discontinuous, there exist no derivations with respect to the parameters that should be optimized. thus, we can only use undirected search methods. In contrast to simple trial-and-error approaches, evolutionary strategies can extract population-based information that guide the search process and help to improve the quality of the results. the paper describes the parallel implementation of an state-of-the-art evolutionary strategy which uses the covariance adaptation operator. It proposes a communication topology for maintaining selective pressure and a master-slave scheme for fault tolerance in distributed environments which are composed of volatile resources. Experimental results demonstrate how the implementation can be adapted to specific needs and how the parallel implementation behaves in the case of resource failures.
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