The paper presents a modeling and simulation method to evaluate the performance of distributed computer control systems (DCCSs). Task response time, resource utilization, and network delay are considered as performanc...
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Modern distributedreal-time embedded applications have high processing requirements associated with strict deadlines. For some applications, such constraints cannot be fulfilled by existing single-core embedded platf...
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Modern distributedreal-time embedded applications have high processing requirements associated with strict deadlines. For some applications, such constraints cannot be fulfilled by existing single-core embedded platforms. A solution is to parallelize the execution of the applications, by allowing networked nodes to distribute their workload to remote nodes with spare capacity. In that context, this paper presents a holistic timing analysis for fixedpriority fork-join parallel/distributed tasks. Furthermore, we extend the holistic approach to consider the interaction between parallel threads and messages interchanged through a flexible time triggered switched Ethernet network, and we show how the pessimism on the worst case response time computation of such tasks can be reduced by considering the pipeline effect that occurs in such distributedsystems. To evaluate the performance and correctness of the holistic model, this paper includes a numerical evaluation based on a real automotive application. The obtained results show that the proposed method is effective in distributing the load by different nodes, allowing a significant reduction of the worst case response time of the tasks. Moreover, the paper also reports an implementation of the model on a Linux library, called parallel/distributedreal-time, as well as the corresponding results obtained on a real testbed. The obtained results are in accordance with the predictions of the holistic timing analysis.
Modem distributed Embedded systems (DESs) tend to be more connected to other peers or external networks. This opens the gate for potential security attacks, although it is beneficial for embedded applications running ...
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Modem distributed Embedded systems (DESs) tend to be more connected to other peers or external networks. This opens the gate for potential security attacks, although it is beneficial for embedded applications running on DESs. Security protections in DESs require significant time and energy overhead. Longer execution time rises the possibility of deadline violation of real-time applications, which may cause serious consequences in hard real-timesystems. Energy efficiency is required since energy budget is usually very scarce under the context of DESs. Therefore, it is of critical importance to study the trade-off between security protection and corresponding timing and energy overheads so that the overall system performance can be maximally improved. In this paper, we approach the design of energy-and security-critical distributedreal-time embedded systems from the early mapping and scheduling phases. We focus on providing the best confidentiality protection of internal communication in DESs under timing and energy constraints. The complexity of finding the optimal solution grows exponentially as the problem size increases. Therefore, we propose an efficient, genetic algorithm based heuristic to solve the problem. In the presented algorithm, solutions are evolved gradually so that good solutions can be obtained. Extensive experiments, including a real-life case study, demonstrate the efficiency of the proposed technique. (C) 2016 Elsevier Inc. All rights reserved.
Use of portable computers with a wireless connection to distributed databases will become as popular as the use of mobile phones in the near future. The rapidly advancing technology in this area initiates new research...
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ISBN:
(纸本)0818685042
Use of portable computers with a wireless connection to distributed databases will become as popular as the use of mobile phones in the near future. The rapidly advancing technology in this area initiates new research areas and challenging research questions recently. One of the new areas is to support real-time database systems, with wireless network. In this paper, we have built a model with sufficient details of a wireless distributedreal-time database system (WDRTDBS) and have performed simulation experiments to identify, the effect of wireless bandwidth, which is one of the most scarce resources in a wireless environment, on the performance of distributedreal-time database systems. Through the experiments, we are trying to figure out the criterion for building efficient wireless DRTDBS in terms of performance. The simulation results reveal that the call duration, which may lead to call blocking and prolonged call waiting, causes much impact on the performance of the DRTDBS in terms of resource contention and transaction deadline missing.
The latest version of real-time CORBA defines a Distributable Thread primitive to support real-time computing in a dynamic distributed environment. However, this standard does not provide support for making and enforc...
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ISBN:
(纸本)0769523471
The latest version of real-time CORBA defines a Distributable Thread primitive to support real-time computing in a dynamic distributed environment. However, this standard does not provide support for making and enforcing global decisions. This paper describes the framework for a distributed Scheduling Service (DSS) that provides globally sound decision-making and scheduling enforcement to real-timedistributedsystems. The paper describes the design and implementation of the framework, as well as preliminary performance results.
The Generic Runtime Infrastructure for distributed Simulation (GRIDS) has been developed to investigate modularity issues in distributed simulation. It could be argued that although the HLA RTI is a widespread solutio...
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ISBN:
(纸本)0769518532
The Generic Runtime Infrastructure for distributed Simulation (GRIDS) has been developed to investigate modularity issues in distributed simulation. It could be argued that although the HLA RTI is a widespread solution to distributed simulation, it cannot include all possible services. This paper investigates an approach to extending the distributed simulation services available in the HLA RTI. One example of this is bridging support for HLA/DIS legacy integration. This paper therefore presents GRIDS, how GRIDS can be used to provide modular service support for the HLA RTI, and a case study on legacy integration to demonstrate our approach.
In real-time simulation, the system being simulated should display the same timing behavior as the target system. The simulation accuracy is increased as the simulation time unit is decreased. Although there are sever...
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ISBN:
(纸本)0769515762
In real-time simulation, the system being simulated should display the same timing behavior as the target system. The simulation accuracy is increased as the simulation time unit is decreased. Although there are several models for such a system, the TMO model is particularly appropriate due to its natural support for real-timedistributed object oriented programming. This paper discusses the results of the implementation of a real-time airplane-landing simulator on a distributed computing environment using the TMO model.
In this paper we discuss the design of parallel interactive continuous media servers suitable for the implementation of scalable server-based media delivery services like Video-on-Demand or Teleshopping. The main desi...
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In this paper we discuss the design of parallel interactive continuous media servers suitable for the implementation of scalable server-based media delivery services like Video-on-Demand or Teleshopping. The main design problems for the development of such servers is to ensure the just-in-time delivery of media elements in order to maximize the Quality of Service and to minimize the buffer size at the user site. Just-in-time delivery means that the media elements should be sent as late as possible to the users but early enough to ensure a continuous replay of the media. This is important because clients have to provide buffer space for data arriving to early. The Quality of Service measures the number of data elements arrived in time at the user side. Thus, the real-time properties of the internal communication network as well as the congestion arising at the disks are of highest importance. We present models for parallel media servers and a very simple scheduler that is fully distributed and can therefore easily be implemented on a scalable parallel continuous media server. For each requested data element the scheduler sends a request to the storage subsystems at a point of time only depending on the deadline of that request, i.e. the time the data has to be delivered to the user, and the length of the path the data has to be routed through the internal network of the parallel server. In order to minimize the buffer space at the user site, and to maximize the Quality of Service, we develop timing strategies for the scheduler using simulation results as well as analytical observations. (C) 1997 Published by Elsevier Science B.V.
One of the objectives of computational grids is to offer applications with the collective computational power of distributed but typically shared heterogeneous resources. Unfortunately, efficiently harnessing the perf...
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One of the objectives of computational grids is to offer applications with the collective computational power of distributed but typically shared heterogeneous resources. Unfortunately, efficiently harnessing the performance potential of such systems (i.e., scheduling) is a challenging endeavor due to the principally distributed, shared and heterogeneous nature of the resources involved. The main focus of this work is devoted to online scheduling of realtime applications in distributed environments Such as grids. Specifically, we are interested in applications, with several independent tasks, and each task labeled with a lifecycle called deadline. Here, our goal is to schedule applications within specified deadlines. To achieve this, performance dynamism of resources is modeled with the help of queuing techniques. A mathematical neural model is employed afterwards, to schedule subtasks of the application. The main contribution of this work is an efficient and fast parallel scheduling algorithm under time constraint and heterogeneous resources, appropriate for implementation in parallel machines in O(1) time. The proposed model was implemented on GridSim toolkit and under various configurations and parameters to evaluate the performance of scheduling algorithms. Simulation experiments have shown that in approximately 96% of cases, our model schedules tasks Successfully and efficiently. (C) 2009 Elsevier B.V. All rights reserved.
We present the design, analysis, and real-time implementation of a distributed computation particle filter on a graphic processing unit (GPU) architecture that is especially suited for fast real-time control applicati...
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We present the design, analysis, and real-time implementation of a distributed computation particle filter on a graphic processing unit (GPU) architecture that is especially suited for fast real-time control applications. The proposed filter architecture is composed of a number of local subfilters that can share limited information among each other via an arbitrarily chosen abstract connected communication topology. We develop a detailed implementation procedure for GPU architectures focusing on distributed resampling as a crucial step in our approach, and describe alternative methods in the literature. We analyze the role of the most important parameters such as the number of exchanged particles and the effect of the particle exchange topology. The significant speedup and increase in performance obtained with our framework with respect to both available GPU solutions and standard sequential CPU methods enable particle filter implementations in fast real-time feedback control systems. This is illustrated via experimental and simulation results using a real-time visual servoing problem of a robotic arm capable of running in closed loop with an update rate of 100 Hz, while performing particle filter calculations that involve over one million particles.
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