Stéphane Genaud

Stéphane Genaud
University of Strasbourg | UNISTRA · ENSIIE

About

53
Publications
6,919
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
552
Citations
Citations since 2016
5 Research Items
147 Citations
20162017201820192020202120220102030
20162017201820192020202120220102030
20162017201820192020202120220102030
20162017201820192020202120220102030

Publications

Publications (53)
Preprint
Full-text available
Currently, multi/many-core CPUs are considered standard in most types of computers including, mobile phones, PCs or supercomputers. However, the parallelization of applications as well as refactoring/design of applications for efficient hardware usage remains restricted to experts who have advanced technical knowledge and who can invest time tuning...
Conference Paper
In the cloud computing model, cloud providers invoice clients for resource consumption. Hence, tools helping the client to budget the cost of running his application are of pre-eminent importance. However, the opaque and multi-tenant nature of clouds make task runtimes variable and hard to predict, and hamper the creation of reliable simulation too...
Chapter
Full-text available
In the cloud computing model, cloud providers invoice clients for resource consumption. Hence, tools helping the client to budget the cost of running his application are of pre-eminent importance. However, the opaque and multi-tenant nature of clouds make task runtimes variable and hard to predict, and hamper the creation of reliable simulation too...
Article
Full-text available
In the field of cloud computing, Infrastructure as a Service (IaaS) provides virtualized on-demand computing resources on a pay-per-use model. IaaS Cloud differ from traditional mutualized infrastructures in that the resources can be dynamically claimed and released, and the real hardware infrastructure is unknown to its users. These properties dra...
Article
Full-text available
More and more attention is focused on cloud computing and on bridging the gap between various providers. Clouds have the benefit of offering pay-per-use on-demand virtualized resources. In this context efficiently scheduling tasks on resources that are heterogeneous in terms of characteristics, diverse in what service level agreements are concerned...
Conference Paper
This work presents a hybrid MPI/OpenMP parallelization strategy for an advection-diffusion problem, arising in a scientific application simulating tokamak’s edge plasma physics. This problem is the hotspot of the system of equations numerically solved by the application. As this part of the code is memory-bandwidth limited, we show the benefit of a...
Article
Full-text available
This paper describes an algorithm that takes a trace of a distributed program and builds a model of all communications of the program. The model is a set of nested loops representing repeated patterns. Loop bodies collect events representing communication actions performed by the various processes, like sending or receiving messages, and participat...
Article
Full-text available
Cloud computing promises the delivery of on-demand pay-per-use access to unlimited resources. Using these resources requires more than a simple access to them as most clients have certain constraints in terms of cost and time that need to be fulfilled. Therefore certain scheduling heuristics have been devised to optimize the placement of client tas...
Conference Paper
Full-text available
This article presents Schlouder, a broker of IaaS cloud resources which can help users to take advantage of IaaS elasticity. The main advantages of Schlouder are its simplicity, its extensibility, and its capability to provide the user with a prediction of the makespan and cost, given the chosen provisioning strategy and before any actual execution...
Conference Paper
Full-text available
Simulation and modeling for performance prediction and profiling is essential for developing and maintaining HPC code that is expected to scale for next-generation exascale systems, and correctly modeling network behavior is essential for creating realistic simulations. In this article we describe an implementation of a flow-based hybrid network mo...
Conference Paper
Full-text available
This paper presents a study of techniques used to speedup a scientific simulation code. The techniques include sequential optimizations as well as the parallelization with OpenMP. This work is carried out on two different multicore shared memory architectures, namely a cutting edge 8×8 core CPU and a more common 2×6 core board. Our target applicati...
Article
Full-text available
Proper modeling of collective communications is essential for understanding the behavior of medium-to-large scale parallel applications, and even minor deviations in implementation can adversely affect the prediction of real-world performance. We propose a hybrid network model extending LogP based approaches to account for topology and contention i...
Conference Paper
Full-text available
Cloud computing is emerging as a leading solution for deploying on-demand applications in both the industry and the scientific community. An important problem which needs to be considered is that of scheduling tasks on existing resources. Since clouds are linked to grid systems much of the work done on the latter can be ported with some modificatio...
Conference Paper
Full-text available
Recent Infrastructure as a Service (IaaS) solutions, such as Amazon's EC2 cloud, provide virtualized on-demand computing resources on a pay-per-use model. From the user point of view, the cloud provides an inexhaustible supply of resources, which can be dynamically claimed and released. In the context of independent tasks, the main pricing model of...
Article
Full-text available
In line with genomics, proteomics has rapidly emerged as a promising field of research enabling the elucidation of numerous life sciences questions [1]. The tremendous progresses in mass spectrometry-based techniques over the last 20 years have led to the possibility to generate massive, highly accurate, qualitative and quantitative mass spectromet...
Technical Report
Full-text available
The study of parallel and distributed applications and platforms, whether in the cluster, grid, peer-to-peer, volunteer, or cloud computing domain, often mandates empirical evaluation of proposed algorithm and system solutions via simulation. Unlike direct experimentation via an application deployment on a real-world testbed, simulation enables ful...
Conference Paper
Full-text available
Recent Infrastructure-as-a-Service offers, such as Amazon's EC2 cloud, provide virtualized on-demand computing resources on a pay-per-use model. From the user point of view, the cloud provides an inexhaustible supply of resources, which can be dynamically claimed and released. This drastically changes the problem of resource provisioning and job sc...
Conference Paper
Full-text available
Simulation is a popular approach for predicting the performance of MPI applications for platforms that are not at one's disposal. It is also a way to teach the principles of parallel programming and high-performance computing to students without access to a parallel computer. In this work we present SMPI, a simulator for MPI applications that uses...
Conference Paper
This paper presents the parallelization of a machine learning method, called the AdaBoost algorithm. The parallel algorithm follows a dynamically load-balanced master-worker strategy, which is parameterized by the granularity of the tasks distributed to workers. We first show the benefits of this version with heterogeneous processors. Then, we stud...
Article
Le document présente une synthèse de travaux sur le déploiement, l'utilisation et les techniques de mise en oeuvre d'applications développées selon un modèle de programmation à passage de messages sur des grilles de calcul. La première partie décrit les performances observées sur la période 2002-2006 sur une plateforme à l'échelle de la France, ain...
Article
Full-text available
We present in this paper a study on fault management in a grid middleware. The middleware is our home-grown software called P2P-MPI. This framework is MPJ compliant, allows users to execute message passing parallel programs, and its objective is to support environments using commodity hardware. Hence, running programs is failure prone and a particu...
Conference Paper
We present in this paper an evaluation of fault management in the grid middleware P2P-MPI. One of P2P-MPI's objective is to support environments using commodity hardware. Hence, running programs is failure prone and a particular attention must be paid to fault management. The fault management covers two issues: fault-tolerance and fault detection....
Article
Full-text available
This chapter describes the P2P-MPI project, a software framework aimed at the development of message-passing programs in large scale distributed networks of computers. Our goal is to provide a light-weight, self-contained software package that requires minimum effort to use and maintain. P2P-MPI relies on three features to reach this goal: i) its i...
Conference Paper
Full-text available
High Performance computing generally involves some parallel applications to be deployed on the multiples resources used for the computation. The problem of scheduling the application across distributed resources is termed as co-allocation. In a grid context, co-allocation is difficult since the grid middleware must face a dynamic environment. Middl...
Article
Full-text available
The goal of clustering is to identify subsets called clusters which usually correspond to objects that are more similar to each other than they are to objects from other clusters. We have proposed the MACLAW method, a cooperative coevolution algorithm for data clus-tering, which has shown good results [4]. However the complexity of the algorithm in...
Conference Paper
Today, clusters are often interconnected by long distance networks to compose grids and to provide users with a huge number of available ressources. To write parallel applications, developers are generally using the standard communication library MPI, which has been optimized for clusters. However, two main features of grids - long distance network...
Conference Paper
Full-text available
We present in this paper the recent developments done in P2P-MPI, a grid middleware, concerning the fault management, which covers fault-tolerance for applications and fault detection. P2P-MPI provides a transparent fault tolerance facility based on replication of com- putations. Applications are monitored by a distributed set of external modules c...
Conference Paper
Full-text available
Over the last couple of years, several dedicated grid platforms have been set up to test applications and middleware for grids. Among these is Grid'5000, a reconfigurable platform gathering resources at nine remote geographical sites in France. This paper presents one of the eight experiments that have tested software scalability at the scale of a...
Article
Full-text available
This paper presents P2P-MPI, a middleware aimed at computational grids. From the programmer point of view, P2P-MPI provides a message-passing programming,model which enables the development of MPI applications for grids. Its originality lies in its adaptation to unstable environments. First, the peer-to-peer design of P2P-MPI allows for a dynamic d...
Article
Many people develop tools for image processing in various languages (C, C++, FORTRAN, MATLAB, etc) but do not diffuse them. One of the reasons is the portability and also the difficulty to make them collaborate with other tools. We have developed an architecture in which such tools can be wrapped and accessed through a standardized way (CGI and Web...
Conference Paper
Full-text available
This paper presents P2P-MPI, a middleware aimed at com- putational grids. From the programmer point of view, P2P-MPI provides a message-passing programming model which enables the development of MPI applications for grids. Its originality lies in its adaptation to un- stable environments. First, the peer-to-peer design of P2P-MPI allows for a dynam...
Article
Full-text available
Seismic tomography enables to model the internal structure of the Earth. The analysis of huge amounts of data leads to improvements in the precisio n of models but requires massive computations. We present a parallel application for seismi c ray-tracing and its exploitation on an experimental computational grid built over the Renater n etwork. The...
Conference Paper
Full-text available
Seismic tomography enables to model the internal structure of the Earth. In order to improve the precision of existing models, a huge amount of acquired seismic data must be analyzed. The analysis of such massive data requires a considerable computing power, which can only be delivered by parallel computational equipments. Yet, parallel computation...
Article
We present solutions to statically load-balance scatter operations in parallel codes run on grids. Our load-balancing strategy is based on the modification of the data distributions used in scatter operations. We study the replacement of scatter operations with parameterized scatters, allowing custom distributions of data. The paper presents: (1) a...
Article
Full-text available
A major research topic in geophysics deals with the modelization of the Earth interior, and seismic tomography is a means to improve knowledge in this field. In order to improve the accuracy of existing methods, huge quantities of information must be computed. We present in this paper the design of a software program imple- menting a fast seismic r...
Article
We present solutions to statically load-balance scatter operations in parallel codes run on grids. Our load-balancing strategy is based on the modication of the data distributions used in scatter operations. We study the replacement of scatter operations with parameterized scatters, allowing custom distributions of data. The paper presents: 1) a ge...
Article
We present solutions to statically load-balance scatter operations in parallel codes run on grids. Our load-balancing strategy is based on the modication of the data distributions used in scatter operations. We study the replacement of scatter operations with parameterized scatters, allowing custom distributions of data. The paper presents: 1) a ge...
Article
In order to improve the accuracy of existing seismic tomography methods, huge quantities of information must be computed. Our objective is to build an adaptive mesh of the Earth so it can translate to an inverse problem of tractable size. The mesh cells size will be adapted depending on the "illumination" quality, that is regions where rays have br...
Conference Paper
Full-text available
La tomographie sismique permet de modéliser la structure interne de la Terre. L'utilisation de très grandes quantités de données permet d'affiner la qualité du modèle, mais requiert une puissance de calcul considérable. Nous présentons dans cet article, l'application parallèle de tomographie que nous avons développée, ainsi que son exploitation sur...
Conference Paper
Full-text available
We present solutions to statically load-balance scatter operations in parallel codes run on Grids. Our load-balancing strategy is based on the modification of the data distributions used in scatter operations. We need to modify the user source code, but we want to keep the code as close as possible to the original. We study the replacement of scatt...
Article
Full-text available
We present load-balancing strategies to improve the performances of parallel MPI applications running in a Grid environment. We analyze the data distribution constraints found in two scientific codes and propose adapted code transformations to load-balance computations. Experimental results confirm that such source code transformations can improve...
Article
We present load-balancing strategies to improve performances of parallel MPI applications running in a Grid environment. We analyze the data distribution constraints found in two scientic codes and propose adapted code transformations to load-balance computations. We present the general framework for our load-balancing techniques. We then describe...
Article
Full-text available
Parallel programs mainly differ from sequential ones in that they include geometrical aspects involved by the hardware architecture. We present in this paper the Pei formalism, which enables to take into account both the geometrical and functional aspects of programs. It provides a refinement calculus mainly used to transform the geometrical charac...
Conference Paper
Full-text available
We present load-balancing strategies to improve performances of parallel MPI applications running in a Grid environment. We analyze the data distribution constraints found in two scientific codes and propose adapted code transformations to load-balance computations. We present the general framework for our load-balancing techniques. We then describ...
Article
Parallel programs mainly differ from sequential ones in that they include geometrical aspects involved by the hardware architecture. We present in this paper the Pei formalism, which enables to take into account both the geometrical and functional aspects of programs. It provides a refinement calculus mainly used to transform the geometrical charac...
Conference Paper
Full-text available
Parallel programs mainly differ from sequential ones in that they include geometrical aspects involved by the hardware architecture. We present in this paper the Pei formalism, which enables to take into account both the geometrical and functional aspects of programs. It provides a refinement calculus mainly used to transform the geometrical charac...
Conference Paper
This article presents a few examples of program transformation strategies in the language Pei. Three strategies are developed : a simplification of the communications, the introduction of broadcasts by removing recursion from data field definitions, and the introduction of a reduction operator. These transformations emphasize the relationships betw...
Article
This article presents a theoretical framework, called PEI, which is a foundation for data parallel programming. This formalism lies on a small but powerful set of primitives : they are operations on data fields and inverse operations. They induce a clear refinement calculus to transform specifications in executable programs by ensuring a safe proce...

Network

Cited By

Projects

Projects (3)
Archived project
Project
IaaS cloud resources management
Project
http://www.p2pmpi.org.