This paper proposes a method for temporal verification of real-time multitasking application properties based on a communicating timed automata IF language. The properties are divided into two kinds: local properties ...
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ISBN:
(纸本)0769522327
This paper proposes a method for temporal verification of real-time multitasking application properties based on a communicating timed automata IF language. The properties are divided into two kinds: local properties of application elements like object creation/destruction, object length, task deadlocks and secondly global properties such as data age, deadline, and time interval verification. These properties are represented by observer automata and verified by the IF2C tool exhaustive simulation. The notion of phase is used to reduce the IF representation graph by partitioning the application on the basis of phases.
In optimistic simulations, checkpointing techniques are often used to reduce the overhead caused by state saving. In this paper, we propose event reconstruction as a technique with which to reduce the overhead caused ...
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ISBN:
(纸本)0769521118
In optimistic simulations, checkpointing techniques are often used to reduce the overhead caused by state saving. In this paper, we propose event reconstruction as a technique with which to reduce the overhead caused by event saving, and compare its memory consumption and execution time to the results obtained by dynamic checkpointing. As the name implies, event reconstruction reconstructs input events and anti-events from the differences between adjacent states, and does not save input events in the event queue. For simulations with fine event granularity and small state size, such as the logic simulation of VLSI circuitry, event reconstruction can yield an improvement in execution time as well as a significant reduction in memory utilization when compared to dynamic checkpointing. Moreover, this technique facilitates load migration because only the state queue needs to be moved from one processor to another.
We investigated the benefit of exploiting the symmetries of graphs for partitioning. We represent the model to be simulated by a weighted graph. Graph symmetries are studied in the theory of permutation groups and can...
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ISBN:
(纸本)0769521118
We investigated the benefit of exploiting the symmetries of graphs for partitioning. We represent the model to be simulated by a weighted graph. Graph symmetries are studied in the theory of permutation groups and can be calculated in polynomial time with the nauty algorithm [15]. We designed an algorithm to extract useful symmetries from the automorphism group, which can be used to create partitions derived from the graph's structure. Our approach is focused on composite graphs, for which identical subgraphs reoccur in the graph. If these identical subgraphs can be mapped onto each other by symmetries, the subgraphs are replaced by equivalent multivertices, resulting in a 'natural' aggregation of vertices. This approach is applied to parallelsimulation of a detailed IP-switch with a conservative synchronous algorithm. The experimental results show that even for good partitions, global and temporal load imbalances are inevitable.
In distributed wargame simulations, the states of simulation entities need to be updated and sent to other simulation nodes in a timely manner, which may incur high overhead on the network. Thus, how to efficiently us...
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ISBN:
(纸本)0769521118
In distributed wargame simulations, the states of simulation entities need to be updated and sent to other simulation nodes in a timely manner, which may incur high overhead on the network. Thus, how to efficiently use the limited bandwidth of the network is very important to the performance of distributed wargame simulations. In this paper, a utility model is proposed to evaluate the relative importance of a simulation entity. In our proposed utility model, the utility of an entity is determined by the number of entities on which this entity may have influence and the distances between this entity and the entities within its area of influence. Based on the utility model, we may devise some flexible updating mechanisms which can utilize the band-width more efficiently. For example, the state updates of an important entity which may have great influence on the simulation could be sent to other nodes with a high frequency;on the other hand, the state updates of an entity with little importance may be sent to other simulation nodes with a low frequency. In this paper, we will focus on the utility computation of a simulation entity rather than the flexible state updating mechanisms for the simulation entities. Our proposed utility computation mechanism is general and can be easily implemented using the HLA services. Experimental results show that the utility computation mechanism incurs little overhead.
In this work we focus on a new technique for making cloning of parallelsimulations more efficient. Cloning provides a means for running multiple similar simulations in parallel where many computations are shared rath...
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ISBN:
(纸本)0769521118
In this work we focus on a new technique for making cloning of parallelsimulations more efficient. Cloning provides a means for running multiple similar simulations in parallel where many computations are shared rather than repeated [12]. A simulation is cloned on an event for a particular set of logical processes, creating new LP clones. The clones diverge as messages from the new LPs arrive at uncloned LPs. Until replication, all the computations for a particular LP are shared between the clones. simulation kernels using cloning achieve efficiency by incrementally replicating logical processes as necessary. This enables regions of the simulation that have not been affected to use the same computations for both the new and old clone. Clearly, the longer replication can be delayed, the more efficient the simulation. We hypothesize that in many cases replication takes place before it is strictly necessary. We propose just-in-time cloning that addresses this issue by relaxing the constraints of simulation cloning to further benefit from shared computations.
distributedsimulation cloning technology is designed to analyze alternative scenarios of a distributedsimulation concurrently within the same simulation execution session. One important goal of the technology is to ...
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ISBN:
(纸本)0769522327
distributedsimulation cloning technology is designed to analyze alternative scenarios of a distributedsimulation concurrently within the same simulation execution session. One important goal of the technology is to optimize execution by avoiding repeated computation amongst independent scenarios. Our research is concerned with the cloning of High Level Architecture (HLA) based distributedsimulations. A decoupled federate architecture is designed to support correct federate cloning at runtime. A federate may spawn clones to explore different scenarios at a decision point. To address the complexity of the overall cloning-enabled distributedsimulation due to increasing scenario spawning, we have devised an efficient and precise scheme to identify and partition scenarios. It is desirable to use an incremental cloning mechanism to replicate only those federates whose states will be affected while the rest remain intact and are shared amongst the original and new scenarios. Our incremental cloning mechanism ensures accurate sharing and initiates cloning only when strictly necessary.
We study the adaptation of an optimistic Time Warp kernel to cross-cluster computing on the Grid. Wide area communication, the primary source of overhead, is off-loaded onto dedicated routing processes. This allows th...
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ISBN:
(纸本)0769521118
We study the adaptation of an optimistic Time Warp kernel to cross-cluster computing on the Grid. Wide area communication, the primary source of overhead, is off-loaded onto dedicated routing processes. This allows the simulation processes to run at full speed and it thus significantly decreases the performance gap caused by the wide area distribution. Further improvements are obtained by employing message aggregation on the wide area links. We achieve many of our objectives for lazy cancellation and moderate communication, but high communication rates with aggressive cancellation remains a challenge.
Regarding permanently increasing complexity and connectivity of technical systems, decreasing innovation cycle times for the design and development, and increasing systems life time, the performance of model and simul...
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ISBN:
(纸本)0769522327
Regarding permanently increasing complexity and connectivity of technical systems, decreasing innovation cycle times for the design and development, and increasing systems life time, the performance of model and simulation development and application becomes a real challenge. One conceptual approach to increase the efficiency and effectiveness of complex models is component-based model design, development and execution based on reusable model components in a distributedsimulation environment. This presentation will summarize state-of-the-art and midterm perspectives of component-based modeling and simulation (M&S), especially focusing on distributedsimulation applications. Starting with a summary of current demands and expectations, this presentation will include methodological approaches for component-based M&S, formal and architectural requirements for its implementation, current status of its technical realization, and of expected benefits, as well. Finally, future demands for research and perspectives for wider application will be discussed.
The proceedings contain 35 papers from the Eight IEEE International Symposium on distributedsimulation and Real-Time Applications DS-RT 2004. The topics discussed include: architecture and evaluation of tele-haptic e...
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ISBN:
(纸本)0769522327
The proceedings contain 35 papers from the Eight IEEE International Symposium on distributedsimulation and Real-Time Applications DS-RT 2004. The topics discussed include: architecture and evaluation of tele-haptic environments;monitoring and analyzing performance of networked virtual environments;shared object manipulation with decorators in virtual environments;software and simulation modeling for real-time software-intensive systems;virtual reality tools for Internet-based robotic teleoperation;collaboration around shared objects in immersive virtual environments;interactive virtual reality on the grid;and load distribution services in HLA.
The Grid provides a new and unrivaled technology for large scale distributedsimulation as it enables collaboration and the use of distributed computing resources. This panel paper presents the views of four researche...
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ISBN:
(纸本)0769522327
The Grid provides a new and unrivaled technology for large scale distributedsimulation as it enables collaboration and the use of distributed computing resources. This panel paper presents the views of four researchers in the area of distributedsimulation and the Grid. Together we try to identify the main research issues involved in applying Grid technology to distributedsimulation and the key future challenges that need to be solved to achieve this goal. Such challenges include not only technical challenges, but also political ones such as management methodology for the Grid and the development of standards. The benefits of the Grid to end-user simulation modelers also are discussed.
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