The suitability of the Time Warp mechanism to perform simulations with real-time constraints is examined. A model for Time Warp is developed that accounts for overheads such as state saving, state restoration, and sen...
ISBN:
(纸本)9781565550551
The suitability of the Time Warp mechanism to perform simulations with real-time constraints is examined. A model for Time Warp is developed that accounts for overheads such as state saving, state restoration, and sending and transmitting positive and negative messages. A criterion called R-schedulability is defined to indicate whether or not computations can meet real-time deadlines. It is shown that if false events (events that will be rolled back or cancelled later) are generated, and there are no committed events with timestamps equal to those of the false events, Time Warp cannot meet the R-schedulability criterion. Further, if aggressive cancellation is used, scheduling guarantees still cannot be made even in the absence of such false events. However, Time Warp using lazy cancellation is shown to be R-schedulable provided such false events do not exist. Finally, based on these results, bounds on the execution time of a Time Warp simulation are derived.
By offering a shared address space across a number of processors connected by a local area network, the distributed shared memory model offers an attractive way of programming parallel-distributed applications. Such p...
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By offering a shared address space across a number of processors connected by a local area network, the distributed shared memory model offers an attractive way of programming parallel-distributed applications. Such programming can be done either using a memory model based on objects or linear memory. Very few performance studies have been made of such systems. The author describes the motivation and the methodology for a project which compares performance of the object model to the linear memory model. Execution-driven simulation is used to analyze the performance and scalability of the systems for appearing fast processors and new highspeed networks.< >
An analytical study of potential pathological performance areas of the Seamless architecture is presented. Seamless is a latency-tolerant, distributed memory, multiprocessor architecture. A key component of the philos...
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An analytical study of potential pathological performance areas of the Seamless architecture is presented. Seamless is a latency-tolerant, distributed memory, multiprocessor architecture. A key component of the philosophy of Seamless, however, is the use of standard, commodity components for a large part of the system. A discussion of the unavoidable implementation compromises imposed by this decision is presented, followed by a summary of some optimistic performance studies. Then an analytical study that parameterizes the predicts the worst-case impact of using standard components is provided. Finally, it is shown that these bottlenecks are manageable via careful generation of target machine code so that the optimistic performance studies become realistic expectations for a range of program behaviors and granularities.< >
The parallel Ada Run-Time System (PARTS), developed at TUB, is the target of an experimental translator that maps sequential Ada to a shared-memory multi-processor. Other modules of the parallel compiler are not expla...
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The parallel Ada Run-Time System (PARTS), developed at TUB, is the target of an experimental translator that maps sequential Ada to a shared-memory multi-processor. Other modules of the parallel compiler are not explained. The paper summarizes the multi-processor run-time system; it explains those instructions that activate multiple processors leading to SPMD execution and discusses the scheduling policy Default architectural attributes of PARTS can be custom-tailored for each run without re-compile. The experiments exposed different machine personalities by measuring execution time profiles of the vector product run on different architectures. The goal is to find experimentally, how well a shared-memory architecture scales up to an increasing problem size, and how well the problem size scales up for a fixed multi-processor configuration. The measurements expose the advantages of shared-memory multi-processor architectures to exploit one dimension of parallelism. However, scalability is limited to the number of memory ports. Therefore another architectural dimension of parallelism, distributed-memory, must be combined with shared memories to achieve Tera-FLOP performance.< >
The authors describe a new parallel image understanding machine RTA/1 design based on the recursive Torus architecture, and proposed a data level parallel processing scheme using parallel data structures. Various type...
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In this paper, a modular neurocontroller for an arbitrary N-DOF (degree of freedom) manipulator is proposed. The recursive nature of the Newton-Euler formulation is used as a base for the modular neurocontroller. The ...
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In this paper, a modular neurocontroller for an arbitrary N-DOF (degree of freedom) manipulator is proposed. The recursive nature of the Newton-Euler formulation is used as a base for the modular neurocontroller. The neural modules can be trained by the direct inverse or indirect adaptive control schemes. Computer simulation results for a 2-DOF SCARA manipulator are given. Due to its modular structure, this neurocontroller can be applied to a manipulator with arbitrary degrees of freedom such as distributed or cellular robotic systems.
Assembly task planning for multiple robots is highly complicated and cumbersome. A new assembly task planning system for multiple robots is proposed to avoid this problem and to improve the flexibility and the reliabi...
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Assembly task planning for multiple robots is highly complicated and cumbersome. A new assembly task planning system for multiple robots is proposed to avoid this problem and to improve the flexibility and the reliability in assembly tasks. In this system, parts with which a machine is composed are handled as part-objects and plans for assembling the machine are automatically generated as results of autonomous behaviors of these objects. The outline of the planning system, based on this concept is described. Some simulation results using a cooperative computational model are given.< >
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