The paper investigates some important transport layer algorithms for wireless sensor networks. On the basis of the single-path-based distributed TCP caching, which work badly when some node on the path be down, adopt ...
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ISBN:
(纸本)0769529097
The paper investigates some important transport layer algorithms for wireless sensor networks. On the basis of the single-path-based distributed TCP caching, which work badly when some node on the path be down, adopt multi-path routing on the network layer and distributed TCP caching on the transport layer to enhance transport reliability. From the simulation results, it improves overall performance in term of end-to-end transport delay comparing with the original DTC algorithm and loads are distributed among the intermediate nodes. And then address some open issues as the research prospects.
If a model shall be executed in a parallel, distributed instead of a sequential manner typically the entire simulation engine has to be exchanged. To adapt the simulation layer more easily to the requirements of a con...
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ISBN:
(纸本)0769521118
If a model shall be executed in a parallel, distributed instead of a sequential manner typically the entire simulation engine has to be exchanged. To adapt the simulation layer more easily to the requirements of a concrete model to be run in a specific environment a component based simulation layer has been developed for JAMES. A set of different simulator components demonstrates that a component-based design facilitates the exchange of simulators and their combination.
Strong reasons exist for executing a large-scale discrete-event simulation on a cluster of processor nodes (each of which may be a shared-memory multiprocessor or a uniprocessor). This is the architecture of the large...
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ISBN:
(纸本)076951104X;0769511058
Strong reasons exist for executing a large-scale discrete-event simulation on a cluster of processor nodes (each of which may be a shared-memory multiprocessor or a uniprocessor). This is the architecture of the largest scale parallel machines, and so the largest simulation problems can only be solved this way. It is a common architecture even in less esoteric settings, and is suitable for memory-bound simulations. This paper describes our approach to porting the SSF simulation kernel to this architecture, using the Message Passing Interface (MPI) system. The notable feature of this transformation is to support an efficient two-level synchronization and communication scheme that addresses cost discrepancies between shared-memory and distributed memory. In the initial implementation, we use a globally synchronous approach between distributed-memory noes, and an asynchronous shared-memory approach within a SMP cluster. The SSF API reflects inherently shared-memory assumptions;we report therefore on our approach for porting an SSF kernel to a cluster of SMP nodes. Experimental results on two architectures are described, for a model of TCP/IP traffic flows over a hierarchical network. The performance on a distributed network of commodity SMPs connected through ethernet is seen to frequently exceed performance on a Sun shared-memory multiprocessor.
A novel micro-kernel approach to building parallel/distributedsimulation systems is presented. Using this approach, a unified system architecture is developed for incorporating, multiple types of simulation processes...
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ISBN:
(纸本)0769523838
A novel micro-kernel approach to building parallel/distributedsimulation systems is presented. Using this approach, a unified system architecture is developed for incorporating, multiple types of simulation processes. The processes hold potential to employ a variety of synchronization mechanisms, and could even alter their choice of mechanism dynamically. Supported mechanisms include traditional lookahead-based conservative and state saving-based optimistic execution approaches. Also supported are newer mechanisms such as reverse computation-based optimistic execution and aggregation-based event processing, all within a single parsimonious application programming interface. The internal implementation and a preliminary performance evaluation of this interface are presented in mu sik, which is an efficient parallel/distributed realization of the microkernel architecture in C++.
parallel Monte Carlo simulation requires reliable RNGs. For sequential machines, good generators exist. A is not at all trivial to find high-quality RNGs for parallel machines. In this paper we present a short review ...
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ISBN:
(纸本)0818684577
parallel Monte Carlo simulation requires reliable RNGs. For sequential machines, good generators exist. A is not at all trivial to find high-quality RNGs for parallel machines. In this paper we present a short review of the main concepts to produce random numbers on parallel processors and, further, we illustrate some phenomena that occur with parallelization.
This paper addresses the issue of efficient and accurate performance prediction of large-scale message-passing applications on high performance architectures using simulation. Such simulators are often based on parall...
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ISBN:
(纸本)076951104X;0769511058
This paper addresses the issue of efficient and accurate performance prediction of large-scale message-passing applications on high performance architectures using simulation. Such simulators are often based on parallel discrete event simulation, typically using the conservative protocol to synchronize the simulation threads. The paper considers how a compiler can be used to automatically extract information about the lookahead present in the application, and how this can be used to improve the performance of the null protocol used for synchronization. These techniques are implemented in the MPI-Sim simulator and dHPF compiler, which had previously been extended to work together for optimizing the simulation of local computational components of an application. The results show that the availability of lookahead information improves the runtime of the simulator by factors of magnitude, with 30-60% improvements being typical for the real-world codes. The experiments also show that these improvements are directly correlated with reductions in the number of null messages required by the simulations.
In a large-scale distributedsimulation with thousands of dynamic objects, efficient communication of data among these objects is an important issue. The broadcasting mechanism specified by the distributed Interactive...
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ISBN:
(纸本)0769506771
In a large-scale distributedsimulation with thousands of dynamic objects, efficient communication of data among these objects is an important issue. The broadcasting mechanism specified by the distributed Interactive simulation (DIS) standards is not suitable for large scale described simulation. In the High Level Architecture (HLA) paradigm, the Runtime Infrastructure (RTI) provides a set of services, sich as data distribution management (DDM) among federates. The goal of the DDM module in RTI is to make the data communication more efficient by sending the data only to those federates that need the data, as opposed to the broadcasting mechanism employed by DIS. Several DDM schemes have appeared in the literature. In this paper we discuss grid-based DDM and develop a DDM model that uses grids for matching the publishing/subscription regions, and for data filtering. We show that appropriate choice of the grid-cell size is crucial in obtaining good performance. We develop an analytical model and derive a formula for identifying the optimal cell size in grid-based DDM.
Recently a new class of synchronization algorithms for parallel discrete event simulation has been proposed, namely the near perfect state information algorithms, which are based on a notion of error potential to cont...
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ISBN:
(纸本)076951104X;0769511058
Recently a new class of synchronization algorithms for parallel discrete event simulation has been proposed, namely the near perfect state information algorithms, which are based on a notion of error potential to control the optimism of event execution. An algorithms of this class, called elastic time algorithm (ETA), has been instantiated. In this algorithm, the error potentials computed using temporal information (next event timestamp, simulation clocks etc.) and is then translated into event execution delay based on a constant factor. In this paper we present a scaled version of ETA (SEAT), in which the error potential is translated into event execution delay based on both a constant factor and an additional scaling factor determined dynamically as a function of the event granularity. We have implemented versions of ETA and SETA for a cluster of PCs connected by a Myrinet switch and we have established in an empirical study that SETA outperforms ETA if there is difference in the granularity of different event types.
Neural systems are composed of a large number of highly-connected neurons and are widely simulated within the neurological community. In this paper, we examine the application of parallel discrete event simulation tec...
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ISBN:
(纸本)0769523838
Neural systems are composed of a large number of highly-connected neurons and are widely simulated within the neurological community. In this paper, we examine the application of parallel discrete event simulation techniques to networks of a complex model called the Hodgkin-Huxley neuron[1]. We describe the conversion of this model into an event-driven simulation, a technique that offers the potential of much greater performance in parallel and distributedsimulations compared to time-stepped techniques. We report results of an initial set of experiments conducted to determine the feasibility of this parallel event-driven Hodgkin-Huxley model and analyze its viability for large-scale neural simulations.
This paper presents the tolerant, hybrid synchronization schema and its benefits for the parallel and distributedsimulation of interconnected computer networks. The hybrid schema combines conservative and optimistic ...
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ISBN:
(纸本)0818679654
This paper presents the tolerant, hybrid synchronization schema and its benefits for the parallel and distributedsimulation of interconnected computer networks. The hybrid schema combines conservative and optimistic synchronization approaches by using lookahead for scheduling special events and using the flexibility of Time Warp in certain cases. In addition to these classical approaches the introduction of the ''tolerance'' allows the distributed modules to simulate further ahead than guaranteed by the conservative synchronization schema. This results in significantly smaller simulation runtimes and many other benefits.
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