A Parallel Out-of-core Multifrontal Method: Storage of Factors on Disk and Analysis of Models for an Out-of-core Active Memory

Jean-Yves L'Excellent 1 Abdou Guermouche 2, 3 Emmanuel Agullo 1
1 GRAAL - Algorithms and Scheduling for Distributed Heterogeneous Platforms
Inria Grenoble - Rhône-Alpes, LIP - Laboratoire de l'Informatique du Parallélisme
3 SCALAPPLIX - Algorithms and high performance computing for grand challenge applications
INRIA Futurs, Université Bordeaux Segalen - Bordeaux 2, Université Sciences et Technologies - Bordeaux 1, École Nationale Supérieure d'Électronique, Informatique et Radiocommunications de Bordeaux (ENSEIRB), CNRS - Centre National de la Recherche Scientifique : UMR5800
Abstract : ABSTRACT The memory usage of sparse direct solvers can be the bottleneck to solve large sparse systems of linear equations of the form Ax=b. In order to solve large problems, we have designed a robust out-of-core solver, in which computed factors are stored on disk. We use large real-life problems (up to several million equations and several hundred million nonzeros) to show that we can significantly reduce the core memory usage in parallel (on up to 128 processors), with a time performance comparable to that of a parallel in-core solver. A careful study shows how the low-level I/O mechanisms impact the performance. We describe a low-level I/O layer that avoids the perturbations introduced by system buffers and allows consistently good performance results. To go significantly further in the memory reduction, it is interesting to also store the intermediate working memory on disk. In this paper we describe algorithmic models to address this issue, and study their potential in terms of both memory requirements and I/O volume. The out-of-core solver discussed in this paper is publicly available and already used by several academic and industrial groups. The results of the algorithmic modelling will be the basis to design a new version of this solver; this work may also be a useful reference for other developers of sparse out-of-core solvers.
Type de document :
Article dans une revue
Parallel Computing, Elsevier, 2008, 34 (6-8), pp.296-317
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https://hal.archives-ouvertes.fr/hal-00358621
Contributeur : Abdou Guermouche <>
Soumis le : mercredi 4 février 2009 - 03:01:34
Dernière modification le : vendredi 11 septembre 2015 - 01:05:53

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  • HAL Id : hal-00358621, version 1

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Jean-Yves L'Excellent, Abdou Guermouche, Emmanuel Agullo. A Parallel Out-of-core Multifrontal Method: Storage of Factors on Disk and Analysis of Models for an Out-of-core Active Memory. Parallel Computing, Elsevier, 2008, 34 (6-8), pp.296-317. <hal-00358621>

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