A DSM protocol ensures that a thread can access data allocated on another machine using some consistency protocol. The consistency protocol can either replicate the data and unify replica changes periodically or the t...
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ISBN:
(纸本)9780889867741
A DSM protocol ensures that a thread can access data allocated on another machine using some consistency protocol. The consistency protocol can either replicate the data and unify replica changes periodically or the thread, upon remote access, can migrate to the machine that hosts the data and access the data there. There is a performance tradeoff between these extremes. Data replication suffers from a high memory overhead as every replicated object or page consumes memory on each machine. On the other hand, it is as bad to migrate threads upon each remote access since repeated accesses to the same distributed data set will cause repeated network communication whereas replication will incur this only once (at the cost of increased administration overhead to manage the replicas). We propose a hybrid protocol that uses selective replication with thread migration as its default. Even in the presence of extreme memory pressure and thread-migrations, our protocol reaches or exceeds the performance that can be achieved by means of manual replication and explicit changes of the application's code.
A continuous dynamic model for the development of a gas field is studied. Two mathematical problems are posed, solved and analyzed. In the direct problem, we are looking for the maximum accumulated profit on a set of ...
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In this paper, we present the LearnLib, a library of tools for automata learning, which is explicitly designed for the systematic experimental analysis of the profile of available learning algorithms and corresponding...
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Event-Based systems (EBS) can efficiently analyze large streams of sensor data in near-realtime. But they struggle with noise or incompleteness that is seen in the unprecedented amount of data generated by the Interne...
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ISBN:
(纸本)9781450332866
Event-Based systems (EBS) can efficiently analyze large streams of sensor data in near-realtime. But they struggle with noise or incompleteness that is seen in the unprecedented amount of data generated by the Internet of Things. We present a generic approach that deals with uncertain data in the middleware layer of distributed event-based systems and is hence transparent for developers. Our approach calculates alternative paths to improve the overall result of the data analysis. It dynamically generates, updates, and evaluates Bayesian Networks based on probability measures and rules defined by developers. An evaluation on position data shows that the improved detection rate justifies the computational overhead.
An analysis of modern computer network intrusion detection systems was carried out. The application of machine and deep learning methods for classification problems has been investigated. The UNSW-NB15 dataset, develo...
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In this paper we present a method and tool to fully automatically infer data-sensitive behavioral models of black-box systems in two coordinated steps: (1) syntactical analysis of the interface descriptions, here give...
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The paper gives an insight of the work done so far in modelling and implementation of user adapted software systems or adaptive web sites. We introduce a five layer framework which gives to our adaptive web based syst...
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We present an improved efficiency Leading Zero Counter for Xilinx FPGAs which improves the path delay while maintaining the resource usage, along with generalizing the scheme to variants whose inputs are of any size. ...
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In the past decade, active automata learning, an originally merely theoretical enterprise, got attention as a method for dealing with black-box or third party systems. Applications ranged from the support of formal ve...
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As memory transactions have been proposed as a language-level replacement for locks, there is growing need for well-defined semantics. In contrast to database transactions, transaction memory (TM) semantics are compli...
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ISBN:
(纸本)9781595939739
As memory transactions have been proposed as a language-level replacement for locks, there is growing need for well-defined semantics. In contrast to database transactions, transaction memory (TM) semantics are complicated by the fact that programs may access the same memory locations both inside and outside transactions. Strongly atomic semantics, where non-transactional accesses are treated as implicit single-operation transactions, remain difficult to provide without specialized hardware support or significant performance overhead. As an alternative, many in the community have informally proposed that a single global lock semantics [18, 10], where transaction semantics are mapped to those of regions protected by a single global lock, provide an intuitive and efficiently implementable model for programmers. In this paper, we explore the implementation and performance implications of single global lock semantics in a weakly atomic STM from the perspective of Java, and we discuss why even recent STM implementations fall short of these semantics. We describe a new weakly atomic Java STM implementation that provides single global lock semantics while permitting concurrent execution, but we show that this comes at a significant performance cost. We also propose and implement various alternative semantics that loosen single lock requirements while still providing strong guarantees. We compare our new implementations to previous ones, including a strongly atomic STM. [24] Copyright 2008 ACM.
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