The simulation of wireless systems such as cellular or personal communication systems comprises both discrete and continuous time processes. To accelerate these simulations, we propose the use of interval jumping, a n...
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The simulation of wireless systems such as cellular or personal communication systems comprises both discrete and continuous time processes. To accelerate these simulations, we propose the use of interval jumping, a novel technique that allows the execution of a continuous time model to proceed in irregularly sized jumps rather than in the traditional time-stepped manner. The foundations for this mechanism are laid out in the light of the simulation of a complex simulation model which includes radio propagation, channel allocation, transmitter power control and user mobility. We conclude with experimental results comparing sequential and parallel execution of these accelerated simulations which indicate the good potential of our technique.
Circuit simulation is a critical bottleneck in VLSI design. This paper describes the implementation of an existing parallel switch-level simulator called MIR-SIM on a shared-memory multiprocessor architecture. The sim...
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Circuit simulation is a critical bottleneck in VLSI design. This paper describes the implementation of an existing parallel switch-level simulator called MIR-SIM on a shared-memory multiprocessor architecture. The simulator uses a set of three different conservative protocols: the null message protocol, the conditional eyelet protocol and the accelerated null message protocol, a combinations of the preceding two algorithms. The paper describes the implementation of these protocols to exploit shared-memory features, measures their relative performance for a set of six benchmark circuits ranging in size from 3000 to almost 70,000 transistors, and compares the speedup obtained by each of the three protocols.
We describe the TED/C++ implementation of WIPPET, a parallelsimulation testbed for evaluating radio resource management algorithms and wireless transport protocols. Versions 0.3 and 0.4 of the testbed model radio pro...
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We describe the TED/C++ implementation of WIPPET, a parallelsimulation testbed for evaluating radio resource management algorithms and wireless transport protocols. Versions 0.3 and 0.4 of the testbed model radio propagation (long- and short-scale fading and interference) and protocols for integrated radio resource management in mobile wireless voice networks including the standards-based AMPS, NA-TDMA and GSM protocols, and several research-oriented protocol families. We provide parallel performance data verifying that the dominant computational demand due to received signal quality calculation can be partitioned geographically, by orthogonal radio channels, or in a hybrid manner.
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 ...
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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 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.
In this paper the performance of the Chandy-Misra algorithm in distributedsimulation has been studied in the context of a particular simulation applications a cellular network. The logical process structure under the...
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ISBN:
(纸本)0818684577
In this paper the performance of the Chandy-Misra algorithm in distributedsimulation has been studied in the context of a particular simulation applications a cellular network. The logical process structure under the algorithm is modified in such a way that the excessive synchronisation caused by the algorithm can be avoided. The synchronisation is minimised by reducing the number of connections between logical processes (LP). The concept of a neighbourhood of an LP is defined in such way that an LP is connected via logical channels only to those LPs that belong to its neighbourhood. A broadcast messages method is proposed to solve the communication between non-connected logical processes, i.e. those outside the neighbourhood. simulation experiments are carried out in a previously implemented distributedsimulation environment, Diworse. A GSM network is used as a simulation application where target of the simulation is to obtain estimates for the channel utilisation. Carrier per interference (C/I) values for GSM channels are used for determining the need for handovers. Execution time of the simulation and deviations in the C/I values are measured for completely connected and broadcast message methods in order to find but the effect of connection reduction. The results indicate that the broadcast messages method enables significantly faster simulation. With the GSM application the proposed method has only a negligible distorting effect to the simulation.
In this paper 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 synchron...
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In this paper 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 compactfication), 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.
This 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: computati...
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This 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 traditional distributedsimulation schemes, entire simulation needs to be restarted if any of the participating LP crashes. This is highly undesirable for long running simulations. Some form of fault-tolerance is r...
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In traditional distributedsimulation schemes, entire simulation needs to be restarted if any of the participating LP crashes. This is highly undesirable for long running simulations. Some form of fault-tolerance is required to minimize the wasted computation. In this paper, a rollback based optimistic fault-tolerance scheme is integrated with an optimistic distributedsimulation scheme. In rollback recovery schemes, checkpoints are periodically saved on stable storage. After a crash, these saved checkpoints are used to restart the computation. We make use of the novel insight that a failure can be modeled as a straggler event with the receive time equal to the virtual time of the last checkpoint saved on stable storage. This results in saving of implementation efforts, as well as reduced overheads. We define stable global virtual time (SGVT), as the virtual time such that no state with a lower timestamp will ever be rolled back despite crash failures. A simple change is made in existing GVT algorithms to compute SGVT. Our use of transitive dependency tracking eliminates antimessages. LPs are clubbed in clusters to minimize stable storage access time.
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. Here, we report on an impleme...
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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. Here, 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 PC's inter-connected 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 proceedings contain 69 papers. The topics discussed include: exploiting the parallel divide-and-conquer method to solve the symmetric tridiagonal eigenproblem;biological sequence analysis on distributed-shared mem...
ISBN:
(纸本)0818683325
The proceedings contain 69 papers. The topics discussed include: exploiting the parallel divide-and-conquer method to solve the symmetric tridiagonal eigenproblem;biological sequence analysis on distributed-shared memory multiprocessors;scheduling tasks in DAG to heterogeneous processor system;effective scheduling in a mixed parallel and sequential computing environment;distributed computation in a three-dimensional mesh with communication delays;automatic performance evaluation of parallel programs;architecture-dependent partitioning of dependence graphs;modeling and simulation of integrated modular avionics;improving parallel computer communication: dynamic routing balancing;using channel pipelining in reconfigurable interconnection networks;and exploiting write semantics in implementing partially replicated casual objects.
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