Multiprocessor systems with a global shared memory provide logically uniform data access. To hide latencies when accessing global memory each processor makes use of a private cache. Several copies of a data item may e...
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Multiprocessor systems with a global shared memory provide logically uniform data access. To hide latencies when accessing global memory each processor makes use of a private cache. Several copies of a data item may exist concurrently in the system. To guarantee consistency when updating an item a processor must invalidate copies of the item in other private caches. To exclude the effect of classical paging faults, one assumes that each processor knows its own data access sequence, but does not know the sequence of future invalidations requested by other processors. Performance of a processor withthis restriction can be measured against the optimal behavior of a theoretical omniscient processor, using competitive analysis. A 4/3 competitive randomized online algorithm for this problem for cache size 2 is presented. this algorithm is derived withthe help of a new concept we call knowledge states. We also prove a matching lower bound, thus this online algorithm is best possible. Finally, a lower bound of 3/2 on the competitiveness for larger cache sizes is shown.
this paper presents the design of a system that supports execution of HLA distributed interactive simulations in an unreliable Grid environment. the design of the architecture is based on the OGSA concept that allows ...
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ISBN:
(纸本)0769520367
this paper presents the design of a system that supports execution of HLA distributed interactive simulations in an unreliable Grid environment. the design of the architecture is based on the OGSA concept that allows for modularity and compatibility with Grid Services already being developed. First of all, we focus on the part of the system which is responsible for migration of a HLA-connected component or components of the distributed application in the Grid environment. We present a runtime support library for easily plugging HLA simulations into the Grid Services Framework. We also present the impact of execution management (namely migration) on overall system performance.
In this paper, we propose adaptive scheduling and bandwidth allocation techniques to efficiently integrate multimedia tasks for MPEG applications in hard real-time systems. the paper describes a server-based mechanism...
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ISBN:
(纸本)0769520367
In this paper, we propose adaptive scheduling and bandwidth allocation techniques to efficiently integrate multimedia tasks for MPEG applications in hard real-time systems. the paper describes a server-based mechanism for assigning the CPU resource to hard real-time tasks and multimedia tasks, respectively. Especially for MPEG video applications, we show how to dynamically control the fraction of the CPU bandwidth allocated to each multimedia task according to the priority. the primary purpose of these techniques is to minimize the mean tardiness of multimedia tasks while satisfying the timing constraints of hard real-time tasks. the performance of the proposed scheduling techniques is compared withthat of similar mechanisms through simulation experiments.
distributed simulation enables participants situated in different geographical locations to share a common virtual world, which is called a distributed Virtual Environment (DVE). Among the different research topics co...
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ISBN:
(纸本)0769520367
distributed simulation enables participants situated in different geographical locations to share a common virtual world, which is called a distributed Virtual Environment (DVE). Among the different research topics concerned with DVEs, there is a current trend of linking Multi-Agent systems and DVEs together. Withthe properties of autonomy, social ability, reactivity and proactiveness, agents can be used to represent entities in DVEs, where fast and accurate decision making is a determining factor of the whole environment. this paper provides a description of integrating agents into an HLA-based distributed simulation. It focuses on how to construct the sensor of an agent with different interest management schemes. Using the JADE (Java Agent DEvelopment Framework) agent toolkit and the High Level Architecture (HLA) in our prototype, a minesweeping game, we outline two different implementations of this game. Due to the dynamic characteristics of agents, a problem of overdue information from the environment is discussed, and we propose an enlarged subscription region method to solve this problem. Moreover, advisories provided by the HLA are adopted to reduce the overheads. Conclusions are drawn based on the experimental results of these implementations.
the High Level Architecture (HLA) is widely used in defense applications as a common framework for modeling and simulation. the Federation Development and Execution Process (FEDEP) is a generalized process to build HL...
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ISBN:
(纸本)0769520367
the High Level Architecture (HLA) is widely used in defense applications as a common framework for modeling and simulation. the Federation Development and Execution Process (FEDEP) is a generalized process to build HLA federations from scratch. However simulation model design, implementation, testing and execution defined in the FEDEP are time consuming and expensive. the Model Construction Environment (MCE) is introduced in this paper as a web-based system to enhance the efficiency of the federation development by reusing the existing Simulation Object Models (SOM) to build new Federation Object Models (FOM). To ensure the compatibility of the SOMs in a FOM, a Matching Algorithm is defined and tested. An Extensible Elements scheme is designed to help shape the characteristics of the FOM/SOMs. this study can contribute to more cost-efficient methodologies for the development and execution of simulation models.
In this paper, we present the implementation of a parallel road traffic. simulation using the concept of Lane Cut Points (LCPs) in the Spider programming environment. LCPs are storage buffers inserted into lane data s...
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ISBN:
(纸本)0769520367
In this paper, we present the implementation of a parallel road traffic. simulation using the concept of Lane Cut Points (LCPs) in the Spider programming environment. LCPs are storage buffers inserted into lane data structures at the road network partition edges. Vehicles enter a partition at the edges from an LCP and exit a partition edge into an LCP at the end of every simulation. step. Spider, a parallel programming environment, which runs on PVM, coordinates the execution of the parallel traffic simulation.
We present a new conservative event-synchronization protocol, time-based synchronization, for parallel discrete-event simulation of mobile ad hoc wireless networks. Simulators that use our protocol proceed at a scaled...
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ISBN:
(纸本)0769520367
We present a new conservative event-synchronization protocol, time-based synchronization, for parallel discrete-event simulation of mobile ad hoc wireless networks. Simulators that use our protocol proceed at a scaled version of real time and send messages that correspond only to transmissions in the simulated network. We show that such simulators can maintain a constant execution time even as the sizes of the networks that they simulate grow. Moreover we show that these simulators, when executed on a custom parallel architecture, are capable of simulating many networks faster than real time.
paralleldistributedcomputing systems provide mechanisms for exploiting parallelism inherent in many scientific and engineering applications. One such programming environment that has successfully demonstrated operat...
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the Grid enables large-scale resource sharing and makes it viable for running large-scale parallel and distributed simulations. the High Level Architecture (HLA) paradigm provides a software platform and interoperabil...
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ISBN:
(纸本)0769520367
the Grid enables large-scale resource sharing and makes it viable for running large-scale parallel and distributed simulations. the High Level Architecture (HLA) paradigm provides a software platform and interoperability interface for simulation components to utilize these hardware resources. However, neither the Grid nor the HLA provides mechanism for resource management for parallel and distributed simulations. It is also noticed that substantial effort is required for writing program that conforms to the Runtime Infrastructure (RTI) requirements because of its complexity. In this paper, we introduce a framework for designing and executing parallel simulation using the RTI. the framework is also designed to assist load balancing and checkpointing. Withthe code library from our framework, the modeler is able to complete the design of a parallel simulation that runs on RTI by specifying the simulation configuration and the handling detail of each event. Our framework incorporates automatic code generation. It also uses Data Distribution Management to route simulation events (interactions) to achieve efficient use of network bandwidth.
the strong tendency to integrate distributed applications with real-it. me communication requirements into existing computer networks, such as the Internet and mobile networks, implies the necessity for quality-of-ser...
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ISBN:
(纸本)0769520367
the strong tendency to integrate distributed applications with real-it. me communication requirements into existing computer networks, such as the Internet and mobile networks, implies the necessity for quality-of-service (QoS) provisioning. In order to judge the quality of distributed real-time applications it is important to study scenarios where concrete applications are communicating via an existing network. Experimentation is even much more flexible, if no real network is used but, instead, network behavior is just reflected by means of a "network emulator" which emulates packet losses and delays. this paper introduces an architecture and a prototype implementation for a network emulator with highly flexible applicability. the behavior of this emulator is controlled optionally by means of analytical or simulation models or by means of traces based on measurements of packet delays and losses. the emulator allows to consider the impact of background loads in detail. Comprehensive case studies covering video transmissions demonstrate that the emulator can even be used in rather complex scenarios with interconnected communication networks.
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