A number of library based parallel and sequential network simulators have been designed. The paper describes a library, called GloMoSim (Global Mobile system Simulator), for parallelsimulation of wireless networks. G...
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A number of library based parallel and sequential network simulators have been designed. The paper describes a library, called GloMoSim (Global Mobile system Simulator), for parallelsimulation of wireless networks. GloMoSim has been designed to be extensible and composable: the communication protocol stack for wireless networks is divided into a set of layers, each with its own API. Models of protocols at one layer interact with those at a lower (or higher) layer only via these APIs. The modular implementation enables consistent comparison of multiple protocols at a given layer. The parallel implementation of GloMoSim can be executed using a variety of conservative synchronization protocols, which include the null message and conditional event algorithms. The paper describes the GloMoSim library, addresses a number of issues relevant to its parallelization, and presents a set of experimental results on the IBM 9076 SP, a distributed memory multicomputer. These experiments use models constructed from the library modules.
We consider the distributedsimulation of queueing networks of FCFS servers with infinite buffers, and irreducible Markovian routing. We first show that for either the conservative or optimistic synchronization protoc...
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We consider the distributedsimulation of queueing networks of FCFS servers with infinite buffers, and irreducible Markovian routing. We first show that for either the conservative or optimistic synchronization protocols the simulation of such networks can prematurely block owing to event buffer exhaustion. Buffer exhaustion can occur in the simulator, whether or not the simulator is stable, and, unlike simulators of feedforward networks, cannot be prevented by interprocessor flow control alone. We propose a simple technique (which we call compactification), which, when used in conjunction with interprocessor flow control, prevents buffer exhaustion. This leads to a general algorithm, for both conservative and optimistic synchronization, that allows one to simulate the queueing network within the finite amount of memory available at each processor. For each algorithm presented, we also provide the proof that it cannot get deadlocked owing to buffer exhaustion.
We present a dynamic load balancing algorithm for parallel discrete event simulation of spatially explicit problems. In our simulations, the space is discretized and divided into subareas, each of which is simulated b...
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We present a dynamic load balancing algorithm for parallel discrete event simulation of spatially explicit problems. In our simulations, the space is discretized and divided into subareas, each of which is simulated by a logical process (LP). Load predictions are done based on the future events that are scheduled for a given LP. The information about the load of the processes is gathered and distributed during the Global Virtual Time calculation. Each LP calculates the new load distribution of the system. The load is then balanced by moving spatial data between neighboring LPs in one round of communications. In our problems, the LPs should be described as being elements of a ring from the point of view of communication. Due to the spatial characteristics, the load can be migrated only between neighboring LPs. We present an algorithm that performs the load balancing in a ring and minimizes the maximum after-balance load.
The paper presents an analytical model for evaluating the performance of Time Warp simulators. The proposed model is formalized based on two important time components in parallel and distributed processing: computatio...
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ISBN:
(纸本)0818684577
The paper presents an analytical model for evaluating the performance of Time Warp simulators. The proposed model is formalized based on two important time components in parallel and distributed processing: computation time and communication time. The communication time is modeled by buffer access time and message transmission time. Logical processes of the Time Warp simulation, and the processors executing them are assumed to be homogeneous. Performance metrics such as rollback probability, rollback distance, elapsed time and Time Warp efficiency are derived. More importantly, we also analyze the impact of cascading rollback waves on the overall Time Warp performance. By rendering the deviation in state numbers of sender-receiver pairs, we investigate the performance of throttled Time Warp scheme. Our analytical model shows that the deviation in state numbers and the communication delay have a profound impact on Time Warp efficiency. The performance model has been validated against implementation results obtained on a Fujitsu AP3000 parallel computer. The analytical framework can be readily used to estimate performance before the Time Warp simulator is implemented.
In previous papers, we have described a reduction model for computing near-perfect state information (NPSI) in support of adaptive synchronization in a parallel discrete event simulation (S. Srinivasan et al., 1995; 1...
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In previous papers, we have described a reduction model for computing near-perfect state information (NPSI) in support of adaptive synchronization in a parallel discrete event simulation (S. Srinivasan et al., 1995; 1995). We report on an implementation of this model on a popular high performance computing platform-a network of workstations-without the use of special purpose hardware. The specific platform is a set of Pentium Pro PCs, interconnected by Myrinet-a Gbps network. We describe the reduction model and its use in our Elastic Time Algorithm. We summarize our design, described in an earlier paper and focus on the details of the implementation of this design. We present performance results that indicate that NPSI is feasible for simulations with medium to large event granularity.
The paper presents an overview of the PARASOL interface and its potential impact on facilitating transfer of technology from the academic researchers to the industrial end users. The PARASOL project aims at developing...
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The paper presents an overview of the PARASOL interface and its potential impact on facilitating transfer of technology from the academic researchers to the industrial end users. The PARASOL project aims at developing scalable direct and iterative solvers and testing them on real problems with respect to applicability and robustness in the industrial applications such as linear structural analysis (MSC/NASTRAN and SESAM), simulation of nonlinear forming and deformation processes (ARC3D and INDEED), and modeling of incompressible viscous flow (POLYFLOW).
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