Analysis of the solution phase of a parallel multifrontal approach

  • Authors:
  • P. Amestoy;I. S. Duff;A. Guermouche;Tz. Slavova

  • Affiliations:
  • Université de Toulouse, INPT (ENSEEIHT)-IRIT, 2, rue Charles-Camichel, F-31071 Toulouse cedex 7, France;CERFACS (Toulouse), 42, Av. Gaspard Coriolis, 31057 Toulouse, France;LaBRI, Univ. Bordeaux 1/INRIA Futurs, 351, cours de la Libération, F-33405 Talence cedex, France;CERFACS (Toulouse), 42, Av. Gaspard Coriolis, 31057 Toulouse, France

  • Venue:
  • Parallel Computing
  • Year:
  • 2010

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Abstract

We study the forward and backward substitution phases of a sparse multifrontal factorization. These phases are often neglected in papers on sparse direct factorization but, in many applications, they can be the bottleneck so it is crucial to implement them efficiently. In this work, we assume that the factors have been written on disk during the factorization phase, and we discuss the design of an efficient solution phase. We will look at the issues involved when we are solving the sparse systems on parallel computers and will consider in particular their solution in a limited memory environment when out-of-core working is required. Two different approaches are presented to read data from the disk, with a discussion on the advantages and the drawbacks of each. We present some experiments on realistic test problems using an out-of-core version of a sparse multifrontal code called MUltifrontal Massively Parallel Solver (MUMPS).