INRIA a CCSD electronic archive server

    Causal-Consistent Reversibility

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    International audienceReversible computing allows one to execute programs both in the standard, forward direction, and backward, going back to past states. In a concurrent scenario, the correct notion of reversibility is causal-consistent reversibility: any action can be undone, provided that all its consequences (if any) are undone beforehand. In this paper we present an overview of the main approaches, results, and applications of causal-consistent reversibility

    A bytecode set for adaptive optimizations

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    International audienceThe Cog virtual machine features a bytecode interpreter and a baseline Just-in-time compiler. To reach the performance level of industrial quality virtual machines such as Java HotSpot, it needs to employ an adaptive inlining com-piler, a tool that on the fly aggressively optimizes frequently executed portions of code. We decided to implement such a tool as a bytecode to bytecode optimizer, implemented above the virtual machine, where it can be written and developed in Smalltalk. The optimizer we plan needs to extend the operations encoded in the bytecode set and its quality heavily depends on the bytecode set quality. The current bytecode set understood by the virtual machine is old and lacks any room to add new operations. We decided to implement a new bytecode set, which includes additional bytecodes that allow the Just-in-time compiler to generate less generic, and hence simpler and faster code sequences for frequently executed primitives. The new bytecode set includes traps for validating speculative inlining de-cisions and is extensible without compromising optimization opportunities. In addition, we took advantage of this work to solve limitations of the current bytecode set such as the maximum number of instance variable per class, or number of literals per method. In this paper we describe this new byte-code set. We plan to have it in production in the Cog virtual machine and its Pharo, Squeak and Newspeak clients in the coming year

    GATB: Toolbox for developing efficient NGS software

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    International audienceThe analysis of NGS data remains a time and space-consuming task. Many efforts have been made to provide efficient data structures for indexing the terabytes of data generated by the fast sequencing machines (Suffix Array, Burrows-Wheeler transform, Bloom Filter, etc.). Mapper tools, genome assemblers, SNP callers, etc., make an intensive use of these data structures to keep their memory footprint as lower as possible. The overall efficiency of NGS software is brought by a smart combination of how data are represented inside the computer memory and how they are processed through the available processing units inside a processor. Developing such software is thus a real challenge, as it requires a large spectrum of competences from high-level data structure and algorithm concepts to tiny details of implementation. The GATB software toolbox aims to lighten the design of NGS algorithms. It offers a panel of high-level optimized building blocks to speed-up the development of NGS tools related to genome assembly and/or genome analysis. The underlying data structure is the de Bruijn graph, and the general parallelism model is multithreading. The GATB library targets standard computing resources such as current multicore processor (laptop computer, small server) with a few GB of memory. From high-level C++ API, NGS programing designers can rapidly elaborate their own software based on state-of-the-art algorithms and data structures of the domain

    Extended Mobility Management and Routing Protocols for Internet-to-VANET Multicasting

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    International audience—Emerging ITS applications such as fleet manage-ment and point of interest distribution require vehicles to have Internet access. However, allowing vehicles to access to the Internet is particularly challenging due to the special char-acteristics of the vehicular environment. So far, multicasting approaches have been demonstrated to be effective for supporting group communication in traditional networks. However, such Internet-to-VANET multicast service involves several challenges including efficient multicast mobility management and multicast message delivery. This paper proposes a scheme that combines the existing multicast mobility management scheme with vehicular networking solutions to achieve Internet-to-VANET multicasting. The proposed scheme aims to: (i) provide multicast mobility management with low control overhead and efficient bandwidth utilization, as well as (ii) extend the service coverage provided by VANET membership management and multicast message delivery protocol. Simulation results indicate that our Motion-MAODV scheme improves the performance of both MAODV and traditional flooding dissemination schemes in terms of both packet delivery ratio and end-to-end transmission latency

    Specific Read Only Data Management for Memory Hierarchy Optimization

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    International audienceThe multiplication of the number of cores inside embedded systems has raised the pressure on the memory hierarchy. The cost of coherence protocol and the scalability problem of the memory hierarchy is nowadays a major issue. In this paper, a specific data management for read-only data is in-vestigated because these data can be duplicated in several memories without being tracked. Based on analysis of stan-dard benchmarks for embedded systems, we show that read-only data represent 62% of all the data used by applications and 18% of all the memory accesses. A specific data path for read-only data is then evaluated by using simulations. On the first level of the memory hierarchy, removing read-only data of the L1 cache and placing them in another read-only cache improve the data locality of the read-write data by 30% and decrease the total energy consumption of the first level memory by 5%

    Computing functions on Jacobians and their quotients

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    International audienceWe show how to efficiently evaluate functions on jacobian varieties and their quo-tients. We deduce a quasi-optimal algorithm to compute (l, l) isogenies between Jacobians of genus two curves

    An enhanced features extractor for a portfolio of constraint solvers

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    International audienceRecent research has shown that a single arbitrarily efficient solver can be significantly outperformed by a portfolio of possibly slower on-average solvers. The solver selection is usually done by means of (un)supervised learning techniques which exploit features extracted from the problem specifica-tion. In this paper we present an useful and flexible framework that is able to extract an extensive set of features from a Constraint (Satisfaction/Optimization) Problem defined in possibly different modeling languages: MiniZinc, FlatZinc or XCSP

    Trace-Based Decision Making in Interactive Application: Case of Tamagotchi systems

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    International audience— We present our exploratory work for situation preselecting in interactive applications, assuming that the application is an Interactive Adaptive System based on a sequence of contextualized "situations". Each situation confines activities and interactions related to a common context, resources and system actors. When one situation is completed, the system has to determine which is the best following one. We introduce in this paper a new preselecting method that identifies possible next situations among all available situations. We propose a strategy using Naïve Bayes based on the analysis of the sets of available traces (the past of users). Combining all obtained results, we get a set of situations, called set of alternatives that can be used in any decision algorithm. We demonstrate our approach on a case study based on Tamagotchi game

    Robust Specification of Real Time Components

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    International audienceSpecification theories for real-time systems allow to reason about in-terfaces and their implementation models, using a set of operators that includes satisfaction, refinement, logical and parallel composition. To make such theories applicable throughout the entire design process from an abstract specification to an implementation, we need to be able to reason about possibility to effectively implement the theoretical specifications on physical systems. In the literature, this implementation problem has already been linked to the robustness problem for Timed Automata, where small perturbations in the timings of the models are intro-duced. We address the problem of robust implementations in timed specification theories. Our contributions include the analysis of robust timed games and the study of robustness with respect to the operators of the theory

    Extraction des zones cohérentes par l'analyse spatio-temporelle d'images de télédétection

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    International audienceThis paper presents a segmentation method of satellite images time series (SITS) in coherent areas, i.e. in geographical regions having homogeneous temporal behavior. The aim of the method is firstly to extract space-time characteristics of an observed region and secondly to obtain this characterization efficiently in terms of computing cost. This method is applied to the characterization of agro-ecological regions of Senegal by the analysis of MODIS images on one year (23 dates).Cet article présente une méthode de segmentation de séries temporelles d'images satellite (SITS) en zones cohérentes, c'est-à-dire en des régions géographiques ayant des com-portements temporels homogènes. L'objectif de cette méthode est, d'une part, d'extraire des caractéristiques spatio-temporelles d'une région observée et, d'autre part, d'obtenir cette ca-ractérisation de manière efficace en temps de calcul pour traiter de grandes masses de données. Cette méthode est appliquée à la caractérisation des régions agro-écologiques du Sénégal par l'analyse des images MODIS sur un an (23 dates). ABSTRACT
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