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).
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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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.
Data distribution management (DDM) is concerned with the problem of efficiently distributing state information among the entities in a distributedsimulation. While heavily studied in the DIS community for training ap...
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Data distribution management (DDM) is concerned with the problem of efficiently distributing state information among the entities in a distributedsimulation. While heavily studied in the DIS community for training applications using real time synchronization, this problem has received considerably less attention for logical time simulations, and little performance data has appeared in this regard. The paper is concerned with evaluating the performance of a logical time synchronized DDM mechanism. A DDM algorithm based on the services specified in the DoD High Level Architecture (HLA) using routing spaces is described, as well as its implementation on a network of workstations environment. Performance measurements indicate that the time overhead to provide correct logical time synchronization of the DDM mechanisms is small, relative to network communication overheads, suggesting that logical time synchronized DDM mechanisms can perform as efficiently as real time synchronized mechanisms in networked workstation environments.
In traditional distributedsimulation schemes, the entire simulation needs to be restarted if any of the participating logical processes (LPs) crash. This is highly undesirable for long running simulations. Some form ...
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In traditional distributedsimulation schemes, the entire simulation needs to be restarted if any of the participating logical processes (LPs) crash. This is highly undesirable for long running simulations. Some form of fault tolerance is required to minimize the wasted computation. 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 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. 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.
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