Title : A Reconfigurable Component Model for HPC

Speaker: Vincent Lanore

Abstract: High-performance applications whose structure changes dynamically during execution are extremely complex to develop, maintain and adapt to new hardware. Such applications would greatly benefit from easy reuse and separation of concerns which are typical advantages of component models. Unfortunately, no existing component model is both HPC-ready (in terms of scalability and overhead) and able to easily handle dynamic reconfiguration. We aim at addressing performance, scalability and programmability by separating locking and synchronization concerns from reconfiguration code. To this end, we propose directMOD, a component model which provides on one hand a flexible mechanism to lock subassemblies with a very small overhead and high scalability, and on the other hand a set of well-defined mechanisms to easily plug various independently-written reconfiguration components to lockable subassemblies. We evaluate both the model itself and a C++/MPI implementation called directL2C.

WG_2015-04-29_Vincent

Title : Design of Survivable VPN Topologies over a Server Provider Network

Speaker: Brigitte Jaumard

Abstract: In the context of multiple-hop working routing for IP layer traffic requests. The design problem is composed of two problems which are simultaneously solved: (i) Finding the most efficient or economical multi-hop routing of the IP traffic flows with different bandwidth granularities over the logical topology, which involves some traffic grooming, (ii) Ensuring that the logical topology is survivable throughout an appropriate mapping of the logical links over the physical topology, if such a mapping exists. In order to solve such a complex multi layer resilient network design problem, we propose a column generation ILP model. It allows exploiting the natural decomposition of the problem and helps devising a scalable solution scheme. We conducted numerical experiments on a German network with 50 nodes and 88 physical links. Not only we could solve much larger data instances than those published in the literature, but also observe than multi-hop routing allows a saving of up to 10% of the number of lightpaths, depending on the traffic load.

Title : Vers un modèle de composants supportant l’ordonnancement de tâches pour le calcul de haute performance

Speaker: Jérome Richard

Abstract: Les applications de haute performance ont une durée de vie souvent plus grande que celle des plate-formes sur lesquelles elles reposent. L’adaptation de ces applications à différentes plate-formes est un processus nécessaire, long et coûteux. Les composants logiciels offrent de nombreux avantages de génie logiciel simplifiant l’adaptation des applications. Parallèlement, on souhaiterait garder de bonnes performances à travers les adaptations. Les modèles d’ordonnancement de graphes de tâches permettent de tirer parti efficacement des architectures hétérogènes tout en apportant des performances portables. Cet présentation propose et évalue un modèle de composants avec ordonnancement de tâches visant à profiter des avantages des deux approches sur des SMP. Les résultats montrent que le modèle proposé dispose d’avantages provenant des approches à composants (séparation des préoccupations) et des approches à tâches (équilibrage de charge).