Scalable and efficient network simulation methods are the method of choice for evaluating and verifying wireless network protocols on a moderate to large scale. This need becomes obvious when simulating very large-sca...
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In this paper, an efficient distributed heuristic-based algorithm is presented, which is based on joint distance-counter threshold scheme. It features a distributed manner by each node in the network needing no global...
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ISBN:
(纸本)3540296395
In this paper, an efficient distributed heuristic-based algorithm is presented, which is based on joint distance-counter threshold scheme. It features a distributed manner by each node in the network needing no global information. Each node in an ad hoc network receives the message from its neighbors and decides whether to operate retransmitting or not according to the signal strength and times of the receiving messages. The algorithm has superiority such as reliability, rebroadcast saving, less communication overhead for broadcasting task, localized and parameter-less behaviors, so it is easy to operate and possesses a good performance in mobile ad hoc communication environments. A comparison with several other existing algorithms is conducted. It shows by simulation results that the new algorithm is more efficient than others.
The proceedings contain 14 papers. The topics discussed include: performance issues in video streaming environments;design and testing of scalable web-based systems with performance constraints;models of dynamic web c...
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ISBN:
(纸本)0769524478
The proceedings contain 14 papers. The topics discussed include: performance issues in video streaming environments;design and testing of scalable web-based systems with performance constraints;models of dynamic web content;performance modeling of P2P file sharing applications;performance model building of pervasive computing;design and performance evaluation of mechanisms for mobile-devices handoff forecast;efficient analysis algorithms for parametric fault trees;a tool set for modeling and simulation of robotic workcells;software performance analysis in UML models;scalable and efficient parallel and distributedsimulation of complex, dynamic and mobile systems;and towards transparent optimistic synchronization in HLA.
Scalable and efficient network simulation methods are the method of choice for evaluating and verifying wireless network protocols on a moderate to large scale. This need becomes obvious when simulating very large-sca...
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ISBN:
(纸本)0769523838
Scalable and efficient network simulation methods are the method of choice for evaluating and verifying wireless network protocols on a moderate to large scale. This need becomes obvious when simulating very large-scale wireless networks such as emerging ad hoc sensor networks in which the number of nodes can be the order of thousands or more, and with very high node density. Unfortunately, simulation of such large-scale wireless networks often requires excessively large amounts of computing resources and can be slow to complete. One approach to achieving higher performance in a large-scale network simulation is the use of parallel or distributedsimulation techniques. However the efficient distributedsimulation of wireless ad hoc networks is still a daunting task. Therefore, we turn our attention to more traditional sequential simulation methods, and seek to reduce the overhead incurred in the Medium Access Control (MAC) state update propagation between wireless nodes. We introduce a novel method called LAMP (LAzy MAC state uPdate), that substantially reduces this overhead, with no loss of accuracy. Using our wireless network simulation tool, we compare the efficiency of the LAMP approach to the more traditional approach, and show a performance improvement of up to a factor of eight, with no loss of accuracy.
Semantic caching is very attractive for use in distributed computing environments based on historical queries and their descriptions, one of whose important issues is how to best maintain semantic caching using a cohe...
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ISBN:
(纸本)3540296395
Semantic caching is very attractive for use in distributed computing environments based on historical queries and their descriptions, one of whose important issues is how to best maintain semantic caching using a coherency control scheme. With the object of applying semantic caching into practice, the cache coherency problems including the data between the server and its caching as well as the cached data and their semantic descriptions are analyzed. This paper presents conflicts existing in semantic caching and their formal definitions, proposes the semantic caching model, and coherency control scheme, meanwhile derives update list optimization algorithm adopted in server and coherency control algorithm used in clients. Finally, the performance of the semantic caching coherency control scheme is examined and analyzed through a simulation study in detail.
Some multimedia content may be divisible into independently routable components, e.g. audio and video flows. As a result media content adaptation services may be linked in serial, parallel and hybrid configurations to...
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If-conversion and predicated execution are widely adopted to eliminate branch misprediction penalty. Previous predication execution depends on compiler to generate explicit predicated instructions, In this paper, a tr...
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ISBN:
(纸本)3540296395
If-conversion and predicated execution are widely adopted to eliminate branch misprediction penalty. Previous predication execution depends on compiler to generate explicit predicated instructions, In this paper, a trace-based predicate mechanism named RIMP (Runtime IMplicit Predication) is discussed. The candidates of if-conversion will be identified during dynamic execution. Conventional trace cache has been modified to store RIMP traces, which include instructions both from fall-through and target block following the conditional branch. Hardware extension will add predication to RIMP trace automatically. With the help of RIMP, legacy applications can benefit from predication mechanism without recompiling source code. simulation of RIMP implementation under diverse microarchitecture configurations is presented in the paper. Results have shown promising performance improvement. In general, RIMP with 64kB trace storage delivers an average 10.3% IPC improvement while actually speeding up the execution time by over 7%.
Compute-intensive simulations are currently good candidates for being executed on distributed computers and Grids, in particular for applications with a large number of input data whose values change throughout the si...
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ISBN:
(数字)9783540321323
ISBN:
(纸本)3540297391
Compute-intensive simulations are currently good candidates for being executed on distributed computers and Grids, in particular for applications with a large number of input data whose values change throughout the simulation time and where the communications are not a critical factor. Although the number of computations usually depends on the bulk of input data, there are applications in which the computational load depends on the particular values of some input data. We propose a general methodology to deal with the problem of improving load balance in these cases. It is divided into two main stages. The first one is an exhaustive study of the parallel code structure, using performance tools, with the aim of establishing a relationship between the values of the input data and the computational effort. The next stage uses this information and provides a mechanism to distribute the load of any particular simulating situation among the computational nodes. A load balancing strategy for the particular case of STEM-II, a compute-intensive application that simulates the behavior of pollutant factors in the air, has been developed, obtaining an important improvement in execution time.
The proceedings contain 69 papers. The special focus in this conference is on distributed Computing. The topics include: Performance of fair distributed mutual exclusion algorithms;a framework for automatic identifica...
ISBN:
(纸本)9783540240761
The proceedings contain 69 papers. The special focus in this conference is on distributed Computing. The topics include: Performance of fair distributed mutual exclusion algorithms;a framework for automatic identification of the best checkpoint and recovery protocol;distributed computation for swapping a failing edge;flexible cycle synchronized algorithm in parallel and distributedsimulation;rule mining for dynamic databases;a novel P2P based e-learn heuristic-based scheduling to maximize throughput of data-intensive grid applications;failure recovery in grid database systems;on design of cluster and grid computing environment toolkit for bioinformatics applications;study of scheduling strategies in a dynamic data grid environment;virtual molecular computing – emulating DNA molecules;complexity of compositional model checking of computation tree logic on simple structures;a multi-agent framework based on communication and concurrency;statistical analysis of a P2P query graph based on degrees and their time-evolution;t-UNITY – a formal framework for modeling and reasoning about timing constraints in real-time systems;finding pareto-optimal set of distributed vectors with minimum disclosure;a fair medium access protocol using adaptive flow-rate control through cooperative negotiation among contending flows in Ad Hoc;an adaptive transmission power control protocol for mobile ad hoc networks;a macro-mobility scheme for reduction in handover delay and signaling traffic in MIPv6;path stability based adaptation of MANET routing protocols;agent-based distributed intrusion alert system;a soft computing intrusion detection system and effect of data encryption on wireless ad hoc network performance.
This paper presents the design and implementation of a reinforcement learning agent that automatically selects appropriate loop scheduling algorithms for parallel loops embedded in time-stepping scientific application...
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This paper presents the design and implementation of a reinforcement learning agent that automatically selects appropriate loop scheduling algorithms for parallel loops embedded in time-stepping scientific applications executing on clusters. There may be a number of such loops in an application, and the loops may have different load balancing requirements. Further, loop characteristics may also change as the application progresses. Following a model-free learning approach, the learning agent assigned to a loop selects from a library the best scheduling algorithm for the loop during the lifetime of the application. The utility of the learning agent is demonstrated by its successful integration into the simulation of wave packets - an application arising from quantum mechanics. Results of statistical analysis using pairwise comparison of means on the running time of the simulation with and without the learning agent validate the effectiveness of the agent in improving the parallel performance of the simulation.
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