References of "Varrette, Sébastien 50003258"
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See detailParaMASK: a Multi-Agent System for the Efficient and Dynamic Adaptation of HPC Workloads
Guzek, Mateusz UL; Besseron, Xavier UL; Varrette, Sébastien UL et al

in 14th IEEE International Symposium on Signal Processing and Information Technology (ISSPIT 2014) (2014, December)

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See detailExploiting the Hard-wired Vulnerabilities of Newscast via Connectivity-splitting Attack
Muszynski, Jakub UL; Varrette, Sébastien UL; Jimenez Laredo, Juan Luis UL et al

in Proc. of the IEEE Intl. Conf. on Network and System Security (NSS 2014) (2014, October)

Newscast is a model for information dissemination and mem- bership management in large-scale, agent-based distributed systems. It deploys a simple, peer-to-peer data exchange protocol. The Newscast pro ... [more ▼]

Newscast is a model for information dissemination and mem- bership management in large-scale, agent-based distributed systems. It deploys a simple, peer-to-peer data exchange protocol. The Newscast pro- tocol forms an overlay network and keeps it connected by means of an epidemic algorithm, thus featuring a complex, spatially structured, and dynamically changing environment. It has recently become very popu- lar due to its inherent resilience to node volatility as it exhibits strong self-healing properties. In this paper, we analyze the robustness of the Newscast model when executed in a distributed environment subjected to malicious acts. More precisely, we evaluate the resilience of Newscast against cheating faults and demonstrate that even a few naive cheaters are able to defeat the protocol by breaking the network connectivity. Concrete experiments are performed using a framework that implements both the protocol and the cheating model considered in this work. [less ▲]

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See detailHPC Performance and Energy-Efficiency of the OpenStack Cloud Middleware
Varrette, Sébastien UL; Plugaru, Valentin UL; Guzek, Mateusz UL et al

in Proc. of the 43rd Intl. Conf. on Parallel Processing (ICPP-2014), Heterogeneous and Unconventional Cluster Architectures and Applications Workshop (HUCAA'14) (2014, September)

Detailed reference viewed: 317 (39 UL)
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See detailAnalysis of the Data Flow in the Newscast Protocol for Possible Vulnerabilities
Muszynski, Jakub UL; Varrette, Sébastien UL; Laredo, J. L. Jiménez et al

in Proc. of Intl. Conf. on Cryptography and Security System (CSS'14) (2014, September)

Detailed reference viewed: 124 (7 UL)
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See detailManagement of an Academic HPC Cluster: The UL Experience
Varrette, Sébastien UL; Bouvry, Pascal UL; Cartiaux, Hyacinthe UL et al

in Proc. of the 2014 Intl. Conf. on High Performance Computing Simulation (HPCS 2014) (2014, July)

The intensive growth of processing power, data storage and transmission capabilities has revolutionized many aspects of science. These resources are essential to achieve high-quality results in many ... [more ▼]

The intensive growth of processing power, data storage and transmission capabilities has revolutionized many aspects of science. These resources are essential to achieve high-quality results in many application areas. In this context, the University of Luxembourg (UL) operates since 2007 an High Performance Computing (HPC) facility and the related storage. The aspect of bridging computing and storage is a requirement of UL service – the reasons are both legal (certain data may not move) and performance related. Nowa- days, people from the three faculties and/or the two Interdisciplinary centers within the UL, are users of this facility. More specifically, key research priorities such as Systems Bio-medicine (by LCSB) and Security, Reliability & Trust (by SnT) require access to such HPC facilities in order to function in an adequate environment. The management of HPC solutions is a complex enterprise and a constant area for discussion and improvement. The UL HPC facility and the derived deployed services is a complex computing system to manage by its scale: at the moment of writing, it consists of 150 servers, 368 nodes (3880 computing cores) and 1996 TB of shared raw storage which are all configured, monitored and operated by three per- sons using advanced IT automation solutions based on Puppet [1], FAI [2] and Capistrano [3]. This paper covers all the aspects in relation to the management of such a complex infrastructure, whether technical or administrative. Most design choices or implemented approaches have been motivated by several years of experience in addressing research needs, mainly in the HPC area but also in complementary services (typically Web-based). In this context, we tried to answer in a flexible and convenient way many technological issues. This experience report may be of interest for other research centers belonging either to the public or the private sector looking for good if not best practices in cluster architecture and management. [less ▲]

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See detailHPC platforms @ UL: Overview (as of 2014) and Usage
Varrette, Sébastien UL; Bouvry, Pascal UL; Georgatos, Fotis et al

Presentation (2014, May)

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See detailComparison of Multi-objective Optimization Algorithms for the JShadObf JavaScript Obfuscator
Bertholon, Benoit UL; Varrette, Sébastien UL; Bouvry, Pascal UL

in Proc. of the 17th Intl. Workshop on Nature Inspired Distributed Computing (NIDISC 2014), part of the 28th IEEE/ACM Intl. Parallel and Distributed Processing Symposium (IPDPS 2014) (2014, May)

With the advent of the Cloud Computing (CC) paradigm and the explosion of new Web Services proposed over the Internet (such as Google Office Apps, Dropbox or Doodle), the protection of the programs at the ... [more ▼]

With the advent of the Cloud Computing (CC) paradigm and the explosion of new Web Services proposed over the Internet (such as Google Office Apps, Dropbox or Doodle), the protection of the programs at the heart of these services becomes more and more crucial, especially for the companies making business on top of these services. The majority of these services are now using the JavaScript programming language to interact with the user as all modern web browsers – either on desktops, game consoles, tablets or smart phones – include JavaScript interpreters making it the most ubiquitous programming language in history. This context renew the interest of obfuscation techniques, i.e. to render a program "unintelligible" without altering its functionality. The objective is to prevent the reverse-engineering on the program for a certain period of time – an absolute protection by this way being unrealistic since stand-alone obfuscation for arbitrary programs has been proven impossible in 2001. In [11], we have presented JSHADOBF, an obfuscation framework based on evolutionary heuristics designed to optimize for a given input JavaScript program, the sequence of transformations that should be applied to the source code to improve its obfuscation capacity. Measuring this capacity is based on the combination of several metrics optimized simultaneously with Multi-Objective Evolutionary Algorithms (MOEAs). In this paper, we extend and complete the experiments made around JSHADOBF to ana- lyze the impact of the underlying Multi-Objective Evolutionary Algorithms (MOEAs) algorithm onto the obfuscation process. In particular, we compare the performances of NSGA-II and MOEAD (two reference algorithms in the optimization domain) on top of JSHADOBF to first obfuscate a pedagogical program inherited from linear algebra, then one of the most popular and widely used JavaScript library: JQuery. [less ▲]

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See detailThéorie des Codes : Compression, Cryptage et Correction
Dumas, J.-G.; Roch, J.-L.; Tannier, E. et al

Book published by Dunod - 2nde (2014)

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See detailEvaluating the HPC Performance and Energy-Efficiency of Intel and ARM-based systems with synthetic and bioinformatics workloads
Plugaru, Valentin UL; Varrette, Sébastien UL; Pinel, Frédéric UL et al

Report (2014)

The increasing demand for High Performance Computing (HPC) paired with the higher power requirements of the ever-faster systems has led to the search for both performant and more energy-efficient ... [more ▼]

The increasing demand for High Performance Computing (HPC) paired with the higher power requirements of the ever-faster systems has led to the search for both performant and more energy-efficient architectures. This article compares and contrasts the performance and energy efficiency of two modern, traditional Intel Xeon and low power ARM-based clusters, which are tested with the recently developed High Performance Conjugate Gradient (HPCG) benchmark and the ABySS, FASTA and MrBayes bioinformatics applications. We show a higher Performance per Watt valuation of the ARM cluster, and lower energy usage during the tests, which does not offset the much faster job completion rate obtained by the Intel cluster, making the latter more suitable for the considered workloads given the disparity in the performance results. [less ▲]

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See detailA Holistic Model of the Performance and the Energy-Efficiency of Hypervisors in an HPC Environment
Guzek, Mateusz UL; Varrette, Sébastien UL; Plugaru, Valentin UL et al

in Concurrency & Computation : Practice & Experience (2014)

Detailed reference viewed: 192 (29 UL)
See detailFoundations of Coding: Compression, Encryption, Error-Correction
Dumas, J.-G.; Roch, J.-L.; Tannier, E. et al

Book published by Wiley Sons (2014)

The topic of this book is the automatic transmission of numerical information. We focus on the structure of information, without regarding the type of transmission support. Information can be of any kind ... [more ▼]

The topic of this book is the automatic transmission of numerical information. We focus on the structure of information, without regarding the type of transmission support. Information can be of any kind as long as we can give a numerical representation of it: for example texts, images, sounds, videos. Transmission of this type of data is ubiquitous in technology, especially in telecommunications. Hence, it is necessary to rely on solid foundations for that transmission to be reliable. In this context, we explain how to structure the information so that its transmission is safe, error-free, efficient and fast. It can be used as a reference book by teachers, researchers or companies involved in telecommunication or information security, such that the information it now contains will be still relevant for the coming years as it was the case until now. [less ▲]

Detailed reference viewed: 151 (1 UL)
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See detailHPC Performance and Energy-Efficiency of Xen, KVM and VMware Hypervisors
Varrette, Sébastien UL; Guzek, Mateusz UL; Plugaru, Valentin UL et al

in Proc. of the 25th Symposium on Computer Architecture and High Performance Computing (SBAC-PAD 2013) (2013, October)

With a growing concern on the considerable energy consumed by HPC platforms and data centers, research efforts are targeting green approaches with higher energy efficiency. In particular, virtualization ... [more ▼]

With a growing concern on the considerable energy consumed by HPC platforms and data centers, research efforts are targeting green approaches with higher energy efficiency. In particular, virtualization is emerging as the prominent approach to mutualize the energy consumed by a single server running multiple VMs instances. Even today, it remains unclear whether the overhead induced by virtualization and the corresponding hypervisor middleware suits an environment as high-demanding as an HPC platform. In this paper, we analyze from an HPC perspective the three most widespread virtualization frameworks, namely Xen, KVM, and VMware ESXi and compare them with a baseline environment running in native mode. We performed our experiments on the Grid’5000 platform by measuring the results of the reference HPL benchmark. Power measures were also performed in parallel to quantify the potential energy efficiency of the virtualized environments. In general, our study offers novel incentives toward in-house HPC platforms running without any virtualized frameworks. [less ▲]

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See detailComparing the Performance and Power Usage of GPU and ARM Clusters for Map-Reduce
Delplace, V.; Manneback, P.; Pinel, Frédéric UL et al

in Proc. of the 3rd Intl. Conf. on Cloud and Green Computing (CGC'13) (2013, October)

Detailed reference viewed: 123 (1 UL)
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See detailPerformance tuning of applications for HPC systems employing Simulated Annealing optimization
Plugaru, Valentin UL; Georgatos, Fotis UL; Varrette, Sébastien UL et al

Report (2013)

Building fast software in an HPC environment raises great challenges as software used for simulation and modelling is generally complex and has many dependencies. Current approaches involve manual tuning ... [more ▼]

Building fast software in an HPC environment raises great challenges as software used for simulation and modelling is generally complex and has many dependencies. Current approaches involve manual tuning of compilation parameters in order to minimize the run time, based on a set of predefined defaults, but such an approach involves expert knowledge, is not scalable and can be very expensive in person-hours. In this paper we propose and develop a modular framework called POHPC that uses the Simulated Annealing meta-heuristic algorithm to automatically search for the optimal set of library options and compilation flags that can give the best execution time for a library-application pair on a selected hardware architecture. The framework can be used in modern HPC clusters using a variety of batch scheduling systems as execution backends for the optimization runs, and will discover optimal combinations as well as invalid sets of options and flags that result in failed builds or application crashes. We demonstrate the optimization of the FFTW library working in conjunction with the high- profile community codes GROMACS and QuantumESPRESSO, whereby the suitability of the technique is validated. [less ▲]

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See detailDependency Analysis for Critical Infrastructure Security Modelling: A Case Study within the Grid'5000 Project
Schaberreiter, Thomas UL; Varrette, Sébastien UL; Bouvry, Pascal UL et al

in Proc. of the 3th IFIP Intl. SeCIHD'2013 Workshop, part of the 8th Intl. Conf. on Availability, Reliability and Security (ARES'13) (2013, September)

Detailed reference viewed: 105 (0 UL)
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See detailShadObf: A C-source Obfuscator based on Multi-objective Optimization Algorithms
Bertholon, Benoit UL; Varrette, Sébastien UL; Martinez, S.

in Proc. of the 16th Intl. Workshop on Nature Inspired Distributed Computing (NIDISC 2013), part of the 27th IEEE/ACM Intl. Parallel and Distributed Processing Symposium (IPDPS 2013) (2013, May)

The Development of the new Cloud Computing paradigm as lead to a reorganisation in the order of the priorities of security issues. When running a private code on a Public Cloud or on any remote machine ... [more ▼]

The Development of the new Cloud Computing paradigm as lead to a reorganisation in the order of the priorities of security issues. When running a private code on a Public Cloud or on any remote machine, its owner have no guarantees that the code cannot be reverse engineered, understood and modified. One of the solution for the code owner in order to protect his intellectual property is to obfuscate his algorithms. The Obfuscation of source code is a mechanism to modify a source code to make unintelligible by humans even with the help of computing resources. More precisely, the objective is to conceal the purpose of a program or its logic without altering its functionality, thus preventing the tampering or the reverse engineering of the program Obfuscation is usually performed by applying transformations to the initial source code, but it reveals many open questions: what transformation should be chosen? In which order should the obfuscator apply them? How can we quantify the obfuscation capacity of a given program? In order to answer these questions, we propose here SHADOBF, an obfuscation framework based on evolutionary heuristics designed to optimize for a given input C program, the sequence of transformations that should be applied to the source code to improve its obfuscation capacity. This last measure involves the combination of well known metrics, coming from the Software Engineering area, which are optimized simultaneously thanks to Multi Objective Evo- lutionary Algorithms (MOEAs). We have validated our approach over a classical matrix multiplication program – experiments on other applications is still in progress. Some experiments, presented here, has been performed on some basic but representative examples to valid the feasibility of the method. [less ▲]

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See detailPerformance Evaluation and Energy Efficiency of High-Density HPC Platforms Based on Intel, AMD and ARM Processors
Jarus, M.; Varrette, Sébastien UL; Oleksiak, A. et al

in Proc. of the Intl. Conf. on Energy Efficiency in Large Scale Distributed Systems (EE-LSDS'13) (2013, April)

Due to growth of energy consumption by HPC servers and data centers many research efforts aim at addressing the problem of energy efficiency. Hence, the use of low power processors such as Intel Atom and ... [more ▼]

Due to growth of energy consumption by HPC servers and data centers many research efforts aim at addressing the problem of energy efficiency. Hence, the use of low power processors such as Intel Atom and ARM Cortex have recently gained more interest. In this arti- cle, we compare performance and energy efficiency of cutting-edge high- density HPC platform enclosures featuring either very high-performing processors (such as Intel Core i7 or E7) yet having low power-efficiency, or the reverse i.e. energy efficient processors (such as Intel Atom, AMD Fusion or ARM Cortex A9) yet with limited computing capacity. Our objective was to quantify in a very pragmatic way these general pur- pose CPUs using a set of reference benchmarks and applications run in an HPC environment, the trade-off that could exist between computing and power efficiency. [less ▲]

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See detailTrust Based Interdependency Weighting for On-line Risk Monitoring in Interdependent Critical Infrastructures
Caldeira, F.; Schaberreiter, Thomas UL; Varrette, Sébastien UL et al

in International Journal of Secure Software Engineering (2013), 4(4), 47-69

Detailed reference viewed: 122 (4 UL)