1,721,409 research outputs found
Replicated computational results (RCR) Report for "Fast random integer generation in an interval"
No full textThe article "Fast Random Integer Generation in an Interval" by Lemire (2018) addressed the problem of reducing the cost of machine instructions needed for the random generation of integer values in a generic interval [0,s). The approach taken by the author is the one of exploiting the rejection method (Neumann 1951) to build an algorithm that almost eliminates the need for performing integer division operations-the algorithm still exploits divisions by powers of two, implemented in the form of cheap shift operations. In more details, the likelihood of not requiring an integer division in the proposed algorithm is 2 L -s/2 L , where L denotes the number of bits used to represent integer values. The author also presents a comparative experimental study where the new algorithm, and its implementation for x86 processors, are compared with solutions offered by common software libraries for different programming languages
La resistenza negli artropodi che frequentano gli ambienti urbani: problematiche e prospettive
No full textNote eco-etologiche sulla Philippia oleae (O.G. COSTA) (Rhynchota, Coccoidea), Lecaniide infeudato sull'olivo in Toscana
No full textA low-overhead constant-time Lowest-Timestamp-First CPU scheduler for high-performance optimistic simulation platforms
No full textAn approach to high-performance discrete event simulation consists of exploiting parallelization techniques. These rely on partitioning the simulation model into multiple, interacting simulation objects, also known as Logical Processes (LPs), which concurrently execute events on different CPUs and/or multiple CPU-cores. However, despite the tendency towards high degree of hardware parallelism, for relatively large models, multi-programming schemes are still needed in order to share a single CPU-core across multiple LPs. Consequently, priority management and CPU-scheduling remain central issues for the effectiveness of any parallel simulation environment. This article focuses on the optimistic approach to parallelism, which is based on speculative processing and maintains event-causality across concurrent LPs via rollback techniques. Specifically, the article presents a low-overhead constant-time implementation of the well known Lowest-Timestamp-First algorithm for the identification of the next LP to be CPU-dispatched. This proposal is suited for contexts where the optimistic simulation system conforms to the best-practice of keeping separate event lists for the hosted LPs. The implementation has been integrated in the open source ROOT-Sim (ROme OpTimistic Simulator) package. The effectiveness of the presented proposal is assessed via an extended performance study, carried out by relying on the game of life as the test-bed application. © 2015 Elsevier B.V. All rights reserved
L'impiego delle trappole cromotropiche nella difesa integrata delle colture: stato attuale e prospettive
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Osservazioni eco-etologiche su un Lecaniide dannoso all'olivo in Toscana: Euphilippia olivina Berlese e Silvestri (Rhinchota, Coccoidea)
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A parallel implementation for optimal lambda-calculus reduction
No full textIn this paper we present a parallel implementation of Lévy's optimal reduction for the λ-calculus [11]. In a similar approach to Lamping's one in [10], we base our work on a graph reduction technique known as directed virtual reduction [3] which is actually a restriction of Danos-Regnier virtual reduction [4]. The parallel implementation relies on a strategy for directed virtual reduction, namely half combustion, which we introduce in this paper. We embed in the implementation both a message aggregation technique, allowing a reduction of the communication overhead, and a fair policy for distributing dynamically originated load among processors. The aggregation technique is mandatory as the granularity of the computation is fine. Through this technique we obtain a linear speedup close to 80% of the ideal one on a shared memory multiprocessor. This result points out the viability of parallel implementations for optimal reduction
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