2009 IEEE International Symposium on Parallel & Distributed Processing, 2009
Asset management for the electricity industry leads to very large stochastic optimization problem... more Asset management for the electricity industry leads to very large stochastic optimization problem. We explain in this article how to efficiently distribute the Bellman algorithm used, re-distributing data and computations at each time step, and we examine the parallelization of a simulation algorithm usually used after this optimization part. We focus on distributed architectures with shared memory multi-core nodes, and we design a multiparadigm parallel algorithm, implemented with both MPI and multithreading mechanisms. Then we lay emphasis on the serial optimizations carried out to achieve high performances both on a dual-core PC cluster and a Blue Gene/P IBM supercomputer with quadcore nodes.
Computational fluid dynamics is an increasingly important application domain for computational sc... more Computational fluid dynamics is an increasingly important application domain for computational scientists. In this paper, we propose and analyze optimizations necessary to run CFD simulations consisting of multibillion-cell mesh models on large processor systems. Our investigation leverages the general industrial Navier-Stokes CFD application, Code_Saturne, developed by Electricité de France for incompressible and nearly compressible flows. In this paper, we outline the main bottlenecks and challenges for massively parallel systems and emerging processor features such as many-core, transactional memory, and thread level speculation. We also present an approach based on an octree search algorithm to facilitate the joining of mesh parts and to build complex larger unstructured meshes of several billion grid cells. We describe two parallel strategies of an algebraic multigrid solver and we detail how to introduce new levels of parallelism based on compiler directives with OpenMP, transactional memory and thread level speculation, for finite volume cell-centered formulation and face-based loops. A renumbering scheme for mesh faces is proposed to enhance thread-level parallelism. and implementations capable of simulating with multibillions of cells or particles are beginning to emerge within the research community. Nevertheless, one of the bigger challenges is to reach this capability with general CFD Navier-Stokes industrial software.
Proceedings of the 2014 Workshop on Workshop on programming models for SIMD/Vector processing - WPMVP '14, 2014
This paper presents a review of algorithmic transforms called High Level Transforms for IBM, Inte... more This paper presents a review of algorithmic transforms called High Level Transforms for IBM, Intel and ARM SIMD multi-core processors to accelerate the implementation of low level image processing algorithms. We show that these optimizations provide a significant acceleration. A first evaluation of 512-bit SIMD Xeon-Phi is also presented. We focus on the point that the combination of optimizations leading to the best execution time cannot be predicted, and thus, systematic benchmarking is mandatory. Once the best configuration is found for each architecture, a comparison of these performances is presented. The Harris points detection operator is selected as being representative of low level image processing and computer vision algorithms. Being composed of five convolutions, it is more complex than a simple filter and enables more opportunities to combine optimizations. The presented work can scale across a wide range of codes using 2D stencils and convolutions.
Accelerating Computational Fluid Dynamics on the IBM Blue Gene/P Supercomputer
2010 22nd International Symposium on Computer Architecture and High Performance Computing, 2010
Abstract Computational Fluid Dynamics (CFD) is an increasingly important application domain for c... more Abstract Computational Fluid Dynamics (CFD) is an increasingly important application domain for computational scientists. In this paper, we propose and analyze optimizations necessary to run CFD simulations consisting of multi-billion-cell mesh models on large ...
Renumbering methods to unleash multi-threaded approaches for a general navier-stokes implementation
Our investigation leverages the general industrial Navier-Stokes open-source Computational Fluid ... more Our investigation leverages the general industrial Navier-Stokes open-source Computational Fluid Dynamics (CFD) application, Code_Saturne, developed by Électricité de France (EDF). We deal with how to take advantage of the emerging processor features such as many-cores, Simultaneous Multi-Threading (SMT) and Thread Level Speculation (TLS), through a mixed MPI/multithreads approach. We focus here on the per-node performance improvements and present the constraints
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Papers by Pascal Vezolle