In this paper, we introduce a new Time Warp system called ROSS: Rensselaer's Optimistic simulation System. ROSS is an extremely modular kernel that is capable of achieving event rates as high as 1,250,000 events p...
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In this paper, we introduce a new Time Warp system called ROSS: Rensselaer's Optimistic simulation System. ROSS is an extremely modular kernel that is capable of achieving event rates as high as 1,250,000 events per second when simulating a wireless telephone network model (PCS) on a quad processor PC server. In a head-to-head comparison, we observe that ROSS out performs the Georgia Tech Time Warp (GTW) system on the same computing platform by up to 180%. ROSS only requires a small constant amount of memory buffers greater than the amount needed by the sequential simulation for a constant number of processors. The driving force behind these high-performance and low memory utilization results is the coupling of an efficient pointer-based implementation framework, Fujimoto's fast GVT algorithm for shared memory multiprocessors, reverse computation and the introduction of Kernel Processes (KPs). KPs lower fossil collection overheads by aggregating processed event lists. This aspect allows fossil collection to be done with greater frequency, thus lowering the overall memory necessary to sustain stable, efficient parallel execution.
The evaluation of network performance under real application loads is carried out by detailed time-intensive and resource-intensive simulations. Moreover, the use of ILP (instruction-level parallel) processors in cc-N...
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Testing distributed applications over the Internet is fraught with problems: due to the inability, to control a wide area network consistent, reproduceable performance experiments are not possible. Here a system is de...
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Testing distributed applications over the Internet is fraught with problems: due to the inability, to control a wide area network consistent, reproduceable performance experiments are not possible. Here a system is described that uses a parallel discrete event simulator that can act as a real-time network emulator. Real Internet Protocol (IP) traffic generated by application programs running on user workstations can interact with modelled traffic in the emulator, thus providing a controlled test environment for distributed applications. parallel execution enables the emulator to simulate large virtual networks and to model traffic interactions that could not be done in real-time sequentially. This paper gives an overview of the emulator and explores the various external data routing methods that the emulator supports. These routing methods allow the emulator to be operated in shared environments with certain constraints, as well as in dedicated test environments. Preliminary performance results are included.
The proceedings contain 12 papers. The topics discussed include: WATIS2: design and application of an environment simulation system for test improvement of control software for automatic logistic systems;preliminary i...
ISBN:
(纸本)0769508375
The proceedings contain 12 papers. The topics discussed include: WATIS2: design and application of an environment simulation system for test improvement of control software for automatic logistic systems;preliminary investigations into distributed computing applications on a beowulf cluster;distributedsimulation over loosely coupled domains;distributed engineering plant simuiatiod stimulation environment accreditation of accuracy;scheduling for very large virtual environments and networked games using visibility and priorities;exploiting temporal uncertainty in time warp simulations;dynamic grid-based multicast group assignment in data distribution management;a hybrid approach to data distribution management;state of the HLN RTI;adapting a supply-chain simulation for HLA;a generic rollback manager for optimistic HLA simulations;HLA-based simulation within an interactive engineering environment;and an approach for stream retrieval over HLA-RTI in distributed virtual environments.
Recent demand for mobile telephone service have been growing rapidly while the electro-magnetic spectrum of frequencies allocated for this purpose remain limited. Any solution to the channel assignment problem is subj...
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ISBN:
(纸本)1581133049
Recent demand for mobile telephone service have been growing rapidly while the electro-magnetic spectrum of frequencies allocated for this purpose remain limited. Any solution to the channel assignment problem is subject to this limitation, as well as the interference constraints between adjacent channels in the spectrum. Channel allocation schemes provide a flexible and efficient access to bandwith in wireless and mobile communication systems. In this paper, we present an efficient distributed algorithm for dynamic channel allocation based upon multual exclusion model, where the channels are grouped by the number of cells in a cluster and each group of channels can not be shared concurrently within the cluster. We describe the algorithm, and report its performance several channel systems using different types of call arrival patterns. Our results indicate that significant low denial rate, low message complexity and low acquisition time can be obtained using our algorithm.
The concept of strong groups is introduced to describe the structure of simulation models. It is shown that logical processes within strong groups process at approximately the same rate and that different strong group...
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The concept of strong groups is introduced to describe the structure of simulation models. It is shown that logical processes within strong groups process at approximately the same rate and that different strong groups can progress at different rates. An algorithm based on the rates of the strong groups is presented to balance the load among the physical processors and for flow control.
It is well known that the critical path provides an absolute lower bound on the execution time of a conservative parallel discrete event simulation. It stands to reason that optimal execution time can only be achieved...
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It is well known that the critical path provides an absolute lower bound on the execution time of a conservative parallel discrete event simulation. It stands to reason that optimal execution time can only be achieved by immediately executing each event on the critical path. However, dynamically identifying the critical event is difficult, if not impossible. We examine several heuristics that might help to determine the critical event, and conduct a performance study to determine the effectiveness of using these heuristics for preferential scheduling.
Algorithms for simulating an ATM switch on a distributed memory multiprocessor are described. These include parallel generation of bursty arrival streams, along with the marking and deleting of lost cells due to buffe...
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Algorithms for simulating an ATM switch on a distributed memory multiprocessor are described. These include parallel generation of bursty arrival streams, along with the marking and deleting of lost cells due to buffer overflows. These algorithms increase the amount of computation carried out independently by each processor and reduce the communication between the processors. When the number of cells lost is relatively small, the run time of the simulation is approximately O(N/P), where N is the total number of cells simulated and P is the number of processors. The cells are processed in intervals of fixed length; that length affects the structure and the performance of the algorithms.
Multi agent systems comprise multiple, deliberative agents embedded in and recreating patterns of interactions. Each agent's execution consumes considerable storage and calculation capacities. For testing multi ag...
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Multi agent systems comprise multiple, deliberative agents embedded in and recreating patterns of interactions. Each agent's execution consumes considerable storage and calculation capacities. For testing multi agent systems, distributedparallelsimulation techniques are required that take the dynamic pattern of composition and interaction of multi-agent systems into account. Analyzing the behavior of agents in virtual, dynamic environments necessitates relating the simulation time to the actual execution time of agents. Since the execution time of deliberative components can hardly be foretold, conservative techniques based on lookahead are not applicable. On the other hand, optimistic techniques become very expensive if mobile agents and the creation and deletion of model components are affected by a rollback. The developed simulation layer of JAMES (a Java Based Agent Modeling Environment for simulation) implements a moderately optimistic strategy which splits simulation and external deliberation into different threads and allows simulation and deliberation to proceed concurrently by utilizing simulation events as synchronization points.
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