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See detailEnergy aware ultrascale systems
Oleksiak, Ariel; Lefèvre, Laurent; Alonso, Pedro et al

in Carretero, J.; Jeannot, E.; Zomaya, A.Y. (Eds.) Ultrascale Computing Systems (2019)

Energy consumption is one of the main limiting factors for the design of ultrascale infrastructures. Multi-level hardware and software optimizations must be designed and explored in order to reduce energy ... [more ▼]

Energy consumption is one of the main limiting factors for the design of ultrascale infrastructures. Multi-level hardware and software optimizations must be designed and explored in order to reduce energy consumption for these largescale equipment. This chapter addresses the issue of energy efficiency of ultrascale systems in front of other quality metrics. The goal of this chapter is to explore the design of metrics, analysis, frameworks and tools for putting energy awareness and energy efficiency at the next stage. Significant emphasis will be placed on the idea of “energy complexity,” reflecting the synergies between energy efficiency and quality of service, resilience and performance, by studying computation power, communication/data sharing power, data access power, algorithm energy consumption, etc. [less ▲]

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See detailLes blockchains en 50 questions: comprendre le fonctionnement et les enjeux de cette technologie innovante
Dumas, J.-G.; Lafourcade, P.; Tichit, A. et al

Book published by Dunod - 1er (2018)

Depuis l’avènement du bitcoin, les innovations liées à la blockchain sont en plein essor. Cet ouvrage tente d’expliquer le fonctionnement de cette technologie innovante mais aussi ses applications au ... [more ▼]

Depuis l’avènement du bitcoin, les innovations liées à la blockchain sont en plein essor. Cet ouvrage tente d’expliquer le fonctionnement de cette technologie innovante mais aussi ses applications au travers de 50 questions comme: - Qu’est-ce qu’une blockchain ? - Quel est le lien entre bitcoin et blockchains ? - Qui sont les mineurs et que font-ils ? - Qu’est ce qu’un consensus ? - Quelle est la part des cryptomonnaies dans l’économie mondiale ? - Qu’est-ce qu’un contrat intelligent ? - Peut-on faire une blockchain sans bloc ? - Comment les blockchains vont changer le monde de demain ? Les réponses à toutes ces questions et à 42 autres sont dans ce livre. [less ▲]

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See detailHybrid MPI+OpenMP Implementation of eXtended Discrete Element Method
Mainassara Chekaraou, Abdoul Wahid UL; Rousset, Alban UL; Besseron, Xavier UL et al

in Proc. of the 9th Workshop on Applications for Multi-Core Architectures (WAMCA'18), part of 30th Intl. Symp. on Computer Architecture and High Performance Computing (SBAC-PAD 2018) (2018, September)

The Extended Discrete Element Method (XDEM) is a novel and innovative numerical simulation technique that ex- tends classical Discrete Element Method (DEM) (which simulates the motion of granular material ... [more ▼]

The Extended Discrete Element Method (XDEM) is a novel and innovative numerical simulation technique that ex- tends classical Discrete Element Method (DEM) (which simulates the motion of granular material), by additional properties such as the chemical composition, thermodynamic state, stress/strain for each particle. It has been applied successfully to numerous industries involving the processing of granular materials such as sand, rock, wood or coke [16], [17]. In this context, computational simulation with (X)DEM has become a more and more essential tool for researchers and scientific engineers to set up and explore their experimental processes. However, increasing the size or the accuracy of a model requires the use of High Performance Computing (HPC) platforms over a parallelized implementation to accommodate the growing needs in terms of memory and computation time. In practice, such a parallelization is traditionally obtained using either MPI (distributed memory computing), OpenMP (shared memory computing) or hybrid approaches combining both of them. In this paper, we present the results of our effort to implement an OpenMP version of XDEM allowing hybrid MPI+OpenMP simulations (XDEM being already parallelized with MPI). Far from the basic OpenMP paradigm and recommendations (which simply summarizes by decorating the main computation loops with a set of OpenMP pragma), the OpenMP parallelization of XDEM required a fundamental code re-factoring and careful tuning in order to reach good performance. There are two main reasons for those difficulties. Firstly, XDEM is a legacy code devel- oped for more than 10 years, initially focused on accuracy rather than performance. Secondly, the particles in a DEM simulation are highly dynamic: they can be added, deleted and interaction relations can change at any timestep of the simulation. Thus this article details the multiple layers of optimization applied, such as a deep data structure profiling and reorganization, the usage of fast multithreaded memory allocators and of advanced process/thread-to-core pinning techniques. Experimental results evaluate the benefit of each optimization individually and validate the implementation using a real-world application executed on the HPC platform of the University of Luxembourg. Finally, we present our Hybrid MPI+OpenMP results with a 15%-20% performance gain and how it overcomes scalability limits (by increasing the number of compute cores without dropping of performances) of XDEM-based pure MPI simulations. [less ▲]

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See detailHigh Performance Computing and Big Data analytics in Luxembourg: Overview and Challenges in the EuroHPC horizon
Besseron, Xavier UL; Varrette, Sébastien UL

Presentation (2018, August)

Accelerating modelling and simulation in the data deluge era requires the appropriate hardware and infrastructure at scale. The University of Luxembourg is active since 2007 to develop its own ... [more ▼]

Accelerating modelling and simulation in the data deluge era requires the appropriate hardware and infrastructure at scale. The University of Luxembourg is active since 2007 to develop its own infrastructure and expertise in the HPC and BD domains. The current state of developments will be briefly reviewed in the context of the national and European HPC strategy in which Luxembourg is starting to play a role. [less ▲]

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See detailPRESENCE: Monitoring and Modelling the Performance Metrics of Mobile Cloud SaaS Web Services
Ibrahim, Abdallah Ali Zainelabden Abdallah UL; Wasim, Muhammad Umer UL; Varrette, Sébastien UL et al

in Mobile Information Systems (2018), 2018(1351386),

Service Level Agreements (SLAs) are defining the quality of the services delivered from the Cloud Services Providers (CSPs) to the cloud customers. The services are delivered on a pay-per-use model. The ... [more ▼]

Service Level Agreements (SLAs) are defining the quality of the services delivered from the Cloud Services Providers (CSPs) to the cloud customers. The services are delivered on a pay-per-use model. The quality of the provided services is not guaranteed by the SLA because it is just a contract. The developments around mobile cloud computing and the advent of edge computing technologies are contributing to the diffusion of the cloud services and the multiplication of offers. Although the cloud services market is growing for the coming years, unfortunately, there is no standard mechanism which exists to verify and assure that delivered services satisfy the signed SLA agreement in an automatic way. The accurate monitoring and modelling of the provided Quality of Service (QoS) is also missing. In this context, we aim at offering an automatic framework named PRESENCE, to evaluate the QoS and SLA compliance of Web Services (WSs) offered across several CSPs. Yet unlike other approaches, PRESENCE aims at quantifying in a fair and by stealth way the performance and scalability of the delivered WS. This article focuses on the first experimental results obtained on the accurate modelisation of each individual performance metrics. Indeed, 19 generated models are provided, out of which 78.9% accurately represent the WS performance metrics for two representative SaaS web services used for the validation of the PRESENCE approach. This opens novel perspectives for assessing the SLA compliance of Cloud providers using the PRESENCE framework. [less ▲]

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Peer Reviewed
See detailPRESENCE: Performance Metrics Models for Cloud SaaS Web Services
Ibrahim, Abdallah Ali Zainelabden Abdallah UL; Wasim, Umer; Varrette, Sébastien UL et al

in Proc. of the 11th IEEE Intl. Conf. on Cloud Computing (CLOUD 2018) (2018, July)

Detailed reference viewed: 138 (9 UL)
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See detailLuxembourg Proposals for Large Scale Architectures for Data Science
Varrette, Sébastien UL

Speeches/Talks (2018)

Detailed reference viewed: 33 (2 UL)
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Peer Reviewed
See detailOn Verifying and Assuring the Cloud SLA by Evaluating the Performance of SaaS Web Services Across Multi-cloud Providers
Ibrahim, Abdallah Ali Zainelabden Abdallah UL; Varrette, Sébastien UL; Bouvry, Pascal UL

in 48th Annual IEEE/IFIP Intl. Conf. on Dependable Systems and Networks Workshops (DNS'18) (2018, June)

Detailed reference viewed: 133 (10 UL)
See detailUL HPC Tutorial: Bio-informatics workflows and applications
Plugaru, Valentin UL; Diehl, Sarah UL; Varrette, Sébastien UL et al

Presentation (2018, June)

Detailed reference viewed: 66 (3 UL)
See detailUL HPC Tutorial: Statistical Computing with R
Ginolhac, Aurélien UL; Emeras, Joseph; Varrette, Sébastien UL et al

Presentation (2018, June)

Detailed reference viewed: 117 (19 UL)
See detailUL HPC Tutorial: (Advanced) Prototyping with Python
Parisot, Clément UL; Diehl, Sarah UL; Varrette, Sébastien UL et al

Presentation (2018, June)

Detailed reference viewed: 74 (4 UL)
See detailUL HPC Tutorial: HPC Containers with Singularity
Plugaru, Valentin UL; Varrette, Sébastien UL; Diehl, Sarah UL et al

Presentation (2018, June)

Detailed reference viewed: 108 (6 UL)
See detailUL HPC Tutorial: HPC workflow with sequential jobs
Cartiaux, Hyacinthe UL; Varrette, Sébastien UL; Plugaru, Valentin UL et al

Presentation (2018, June)

Detailed reference viewed: 124 (11 UL)
See detailUL HPC Tutorial: Advanced Job scheduling with SLURM and OAR
Plugaru, Valentin UL; Varrette, Sébastien UL; Diehl, Sarah UL et al

Presentation (2018, June)

Detailed reference viewed: 100 (5 UL)