In message passing environments, the message send time is dominated by overheads that are relatively independent of the message size. Therefore, fine-grained applications (such as Time-Warp simulators) suffer high ove...
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In message passing environments, the message send time is dominated by overheads that are relatively independent of the message size. Therefore, fine-grained applications (such as Time-Warp simulators) suffer high overheads because of frequent communication. In this paper, we investigate the optimization of the communication subsystem of Time-Warp simulators using dynamic message aggregation. Under this scheme, Time-Warp messages with the same destination LP, occurring in close temporal proximity are dynamically aggregated and sent as a single physical message. Several aggregation strategies that attempt to minimize the communication overhead without harming the progress of the simulation (because of messages being delayed) are developed. The performance of the strategies is evaluated for a network of workstations, and an SMP, using a number of applications that have different communication behavior.
parallelization is a popular technique for improving the performance of discrete event simulation. Due to the complex, distributed nature of parallelsimulation algorithms, debugging implemented systems is a daunting,...
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ISBN:
(纸本)9780897919548
parallelization is a popular technique for improving the performance of discrete event simulation. Due to the complex, distributed nature of parallelsimulation algorithms, debugging implemented systems is a daunting, if not impossible task. Developers are plagued with transient errors that prove difficult to replicate and eliminate. Recently, researchers at The University of Cincinnati developed a parallelsimulation kernel, WARPED, implementing a generic parallel discrete event simulator based on the Time Warp optimistic synchronization algorithm. The intent was to provide a common base from which domain specific simulators can be developed. Due to the complexity of the Time Warp algorithm and the dependence of many simulators on the simulation kernel's correctness, a formal specification was developed and verified for critical aspects of the Time Warp system. This paper describes these specifications, their verification and their interaction with the development process.
Mastering increasing complexity of civil airborne equipment systems needs new architectural concepts mainly based on modular design, generic resources and multiplexed communication buses. These new architectures, such...
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ISBN:
(纸本)0818683325
Mastering increasing complexity of civil airborne equipment systems needs new architectural concepts mainly based on modular design, generic resources and multiplexed communication buses. These new architectures, such as Integrated Modular Avionics (IMA) architecture, rely on the definition of standardized hardware and software. However the development of an IMA architecture requires new tools enabling platform designer, applications developer and system integrator to describe and evaluate different implementation choices. This paper, identifies and characterizes different levels of needed models in order to catch essential information for performance evaluation of avionics applications integrated in IMA. Four model levels are proposed: application model, architectural model, execution model and allocation model. These different modeling levels allow the generation of a simulation model of avionics systems allocated on an IMA platform.
This paper describes a database approach to parallel discrete event simulation. It employs a set of production rules to describe the behavior of active objects in a simulation system so that production rules can be me...
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ISBN:
(纸本)0818685824
This paper describes a database approach to parallel discrete event simulation. It employs a set of production rules to describe the behavior of active objects in a simulation system so that production rules can be merged and evaluated collectively in a rule network. To maintain correctness and exploit all possible parallelism, each token is time-stamped and can be processed asynchronously. An object relational database is employed to allow simulators located at different sites of an Intranet to communicate with each other. A dynamic, object-relational query tool is provided for the user to interact with the simulation system.
The proceedings contain 18 papers. The topics discussed include: scheduling resources in multi-user, heterogeneous, computing environments with SmartNet;the Globus project: a status report;Netsolve: a network-enabled ...
ISBN:
(纸本)0818683651
The proceedings contain 18 papers. The topics discussed include: scheduling resources in multi-user, heterogeneous, computing environments with SmartNet;the Globus project: a status report;Netsolve: a network-enabled solver;examples and users;implementing distributed synthetic forces simulations in metacomputing environments;CCS resource management in networked HPC systems;a dynamic matching and scheduling algorithm for heterogeneous computing systems;dynamic, competitive scheduling of multiple DAGS in a distributed heterogeneous environment;the relative performance of various mapping algorithms is independent of sizable variances in run-time predictions;modeling the slowdown of data-parallel applications in homogeneous and heterogeneous clusters of workstations;specification and control of cooperative work in a heterogeneous computing environment;a mathematical model, heuristic, and simulation study for a basic data staging problem in a heterogeneous networking environment;modular heterogeneous system development: a critical analysis of java;fault-tolerance: Java's missing buzzword;heterogeneous parallel computing with Java: jabber or justified?;on the interaction between mobile processes and objects;steps toward understanding performance in Java;and heterogeneous programming with Java: gourmet blend or just a hill of beans?.
Real-time transactions, in addition to preserving consistency of the database as in traditional transactions, have to meet the deadlines. Scheduling real-time transactions in parallel database systems has not received...
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Real-time transactions, in addition to preserving consistency of the database as in traditional transactions, have to meet the deadlines. Scheduling real-time transactions in parallel database systems has not received much attention. This paper focuses on real-time transaction scheduling in shared-nothing parallel database systems. We evaluate the performance of a new priority-based scheduling policy, in which all scheduling decisions are made locally by each node. In contrast, several other algorithms, proposed for the distributed systems, require communication among the nodes to globally synchronize their local block and abort decisions. Such synchronization can deteriorate performance as real-time transactions will have to meet deadlines. We use miss ratio as the performance metric and show that, in general, the new policy provides a superior performance for the workload and system parameters considered in this study.
parallel Monte Carlo simulation requires reliable RNGs. For sequential machines, good generators exist. It is not at all trivial to find high quality RNGs for parallel machines. We present a review of the main concept...
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parallel Monte Carlo simulation requires reliable RNGs. For sequential machines, good generators exist. It is not at all trivial to find high quality RNGs for parallel machines. We present a review of the main concepts to produce random numbers on parallel processors and further, we illustrate some phenomena that occur with parallelization.
We discuss the use and possible abuse of linear and inversive pseudorandom numbers (PRNs) in parallel and distributed environments. After an investigation of properties of PRNs which determine how these may be applied...
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We discuss the use and possible abuse of linear and inversive pseudorandom numbers (PRNs) in parallel and distributed environments. After an investigation of properties of PRNs which determine how these may be applied in such environments, we introduce a software package which provides a unified and easy to use approach to the generating and handling of parallel streams of such PRNs. Experimental results are conducted which describe the features of the software package and compare the performance of two selected types of pseudorandom number generators.
In this paper, the relationship between the computational models of object-oriented rewriting and parallel discrete-event simulation models is explored. A discrete-event simulation program in which several objects int...
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In this paper, the relationship between the computational models of object-oriented rewriting and parallel discrete-event simulation models is explored. A discrete-event simulation program in which several objects interact with each other by exchanging messages may have a high degree of concurrency (which can be exploited using optimistic or conservative parallelsimulation methods). We report on some observations on using rewriting logic in the field of parallel discrete event simulations, and investigate how parallelsimulation applications can be expressed using object-oriented rewriting.
A probabilistic scheduling policy for selecting the next event to be processed by a processor during optimistic parallel discrete event simulation is presented. This policy exploits the knowledge about statistical dis...
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A probabilistic scheduling policy for selecting the next event to be processed by a processor during optimistic parallel discrete event simulation is presented. This policy exploits the knowledge about statistical distributions of the difference between the timestamps of successively committed events of a logical process. simulation results are presented to demonstrate that under appropriate conditions, probabilistic scheduling generates substantially fewer rollbacks compared to the lowest timestamp first scheduling policy.
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