Researching methods for efficient hardware specification, design and implementation of a next generation communication architecture

The objective of this work is to create and implement a System Area Network (SAN) architecture called EXTOLL embedded in the current world of systems, software and standards based on the experiences obtained during the ATOLL project development and test. The topics of this work also cover system design methodology and educational issues in order to provide appropriate human resources and work premises. The scope of this work in the EXTOLL SAN project was: • the Xbar architecture and routing (multi-layer routing, virtual channels and their arbitration, routing formats, dead lock aviodance, debug features, automation of reuse) • the on-chip module communication architecture and parts of the host communication • the network processor architecture and integration • the development of the design methodology and the creation of the design flow • the team education and work structure. In order to successfully leverage student know-how and work flow methodology for this research project the SEED curricula changes has been governed by the Hochschul Didaktik Zentrum resulting in a certificate for "Hochschuldidaktik" and excellence in university education. The complexity of the target system required new approaches in concurrent Hardware/Software codesign. The concept of virtual hardware prototypes has been established and excessively used during design space exploration and software interface design

Evaluation et amélioration des performances d'une implémentation MPI pour la grille

Les applications parallèles utilisent généralement le standard MPI pour réaliser leurs communications. La plupart des implémentations de MPI sont destinées aux grappes homogènes. Avec l'apparition des grilles de calcul, il est nécessaire de faire évoluer ces implémentations pour les adapter efficacement aux contraintes de ces nouvelles plateformes que sont la gestion de l'hétérogénéité et la prise en compte des liens réseau longue distance permettant l'interconnexion des sites de la grille. Aucune implémentation actuelle ne prend en compte efficacement ces deux paramètres. Après une étude des implémentations existantes, cet article analyse le comportement sur la grille de l'une d'entre elles, MPICH-Madeleine, qui propose une gestion efficace de l'hétérogénéité des réseaux rapides de grappe. A partir de nos premières expérimentations, nous proposons des optimisations permettant d'améliorer les performances d'exécution sur la grille. Elles nous ont permis d'augmenter très sensiblement la bande passante lors de l'exécution d'un ping-pong MPI : en passant de 95Mb/s à 600Mb/s sur la longue distance. Les expérimentations ont été réalisées sur la grille française Grid'5000

Evaluation et amélioration des performances d'une implémentation MPI pour la grille

Les applications parallèles utilisent généralement le standard MPI pour réaliser leurs communications. La plupart des implémentations de MPI sont destinées aux grappes homogènes. Avec l'apparition des grilles de calcul, il est nécessaire de faire évoluer ces implémentations pour les adapter efficacement aux contraintes de ces nouvelles plateformes que sont la gestion de l'hétérogénéité et la prise en compte des liens réseau longue distance permettant l'interconnexion des sites de la grille. Aucune implémentation actuelle ne prend en compte efficacement ces deux paramètres. Après une étude des implémentations existantes, cet article analyse le comportement sur la grille de l'une d'entre elles, MPICH-Madeleine, qui propose une gestion efficace de l'hétérogénéité des réseaux rapides de grappe. A partir de nos premières expérimentations, nous proposons des optimisations permettant d'améliorer les performances d'exécution sur la grille. Elles nous ont permis d'augmenter très sensiblement la bande passante lors de l'exécution d'un ping-pong MPI : en passant de 95Mb/s à 600Mb/s sur la longue distance. Les expérimentations ont été réalisées sur la grille française Grid'5000

Fault-tolerant routing in SCI networks

Fault-tolerant routing has been a hot topic in the academic community for quite some time now, and several different approaches have been suggested. In the interconnect industry however, fault-tolerant routing has not been implemented to the same extent. In this thesis we have adapted and implemented a local fault-tolerant routing approach in SCI interconnect technology produced by Dolphin Interconnect Solutions. The existing technology used in SCI is based in a static reconfiguration approach, where the traffic is disabled, while the new routing is calculated by a central front-end and distributed out to the nodes. Our algorithm builds upon the principle of enabling the nodes to make routing decisions from the information that is available to them locally, and having the rest of the nodes in the cluster to be prepared for this unexpected traffic. The algorithm has been tested on real hardware, and we have shown that it can handle several levels of traffic in the network. The test has also proven that our method gives the same performance both before and after the error occurs if the packets have the same conditions, such as competing traffic and link length. Our routing algorithm is currently integrated as a part of Dolphin Interconnect Solutions driver in the last official release

Contribution à l'élaboration d'environnements de programmation dédiés au calcul scientifique hautes performances

Dans le cadre du calcul scientifique intensif, la quête des hautes performances se heurte actuellement à la complexité croissante des architectures des machines parallèles. Ces dernières exhibent en particulier une hiérarchie importante des unités de calcul et des mémoires, ce qui complique énormément la conception des applications parallèles. Cette thèse propose un support d’exécution permettant de programmer efficacement les architectures de type grappes de machines multiprocesseurs, en proposant un modèle de programmation centré sur les opérations collectives de communication et de synchronisation et sur l’équilibrage de charge. L’interface de programmation, nommée MPC, fournit des paradigmes de haut niveau qui sont implémentés demanière optimisée en fonction de l’architecture sous-jacente. L’environnement est opérationnel sur la plate-forme de calcul du CEA/ DAM (TERANOVA) et les évaluations valident la pertinence de l’approche choisie.In the field of intensive scientific computing, the quest for performance has to face the increasing complexity of parallel architectures. Nowadays, thesemachines exhibit a deepmemory hierarchy which complicates the design of efficient parallel applications. This thesis proposes a programming environment allowing to design efficient parallel programs on top of clusters of multiprocessors. It features a programming model centered around collective communications and synchronizations, and provides load balancing facilities. The programming interface, named MPC, provides high level paradigms which are optimized according to the underlying architecture. The environment is fully functional and used within the CEA/DAM(TERANOVA) computing center. The evaluations presented in this document confirm the relevance of our approach

Hybrid Lattice Boltzmann - Molecular Dynamics Simulations With Both Simple and Complex Fluids

The behaviour and properties of colloidal suspensions strongly depend on the interactions arising between the immersed colloidal particles and the solvent. However, modelling such interactions is not at all straightforward; the larger time and length scales experienced by the colloidal particles compared to the solvent molecules makes all-atom molecular dynamics (MD) simulations of such systems completely impractical. Therefore a coarse-grained representation of the fluid is required, along with a method to couple this fluid to the colloidal particles. In the first part of this thesis, we propose a new method for coupling both point and composite MD particles to an isotropic lattice-Boltzmann fluid. This coupling is implemented through the use of conservative forces, calculated by assuming elastic collisions between the particles and the fluid. With the implementation of a thermal lattice-Boltzmann method, the fluid acts as a heat bath for the MD particles without requiring external Langevin noise. This method has been implemented into the open source molecular dynamics package, LAMMPS, providing an efficient technique for explicitly including hydrodynamic interactions in MD simulations. If a liquid crystal (LC) is used as a solvent instead of an isotropic fluid, anisotropic forces develop among the immersed colloidal particles even in the absence of flow. These forces arise due to a preferred orientation of the LC molecules on the colloidal surface, leading to the formation of topological defects in the bulk LC. A thorough understanding of the resulting forces is important, as their anisotropic nature could potentially be used to manufacture non-close packed photonic colloidal crystals. In the second part of this thesis, we use a lattice-Boltzmann LC algorithm to investigate the interactions arising among colloidal particles in a LC. Using a cholesteric LC, we present results for a defect bonded particle chain, and a diamond colloidal crystal. In addition, as the defects and distortions generated in the LC result in a non-uniform pressure exerted on the particle surface, we also investigate the behaviour of 2D deformable particles in a nematic, as any potential shape change could have a significant impact on the resulting interactions