On Tue, Oct 27, 2009 at 10:12 AM, francois pacull <fpacull at fluorem.com>wrote:
> Dear PETSc team, > > I have a few questions... During the resolution of a linear system in > parallel, I am trying to apply a local LU solver to each of the SEQaij > diagonal blocks of a MPIaij matrix partitioned with PARMETIS. > > - I started with MUMPS but it seems that it only works with unpartitioned > aij matrices, is it really the case? Or could we use MUMPS to build an > additive Schwarz preconditioner for example? > You can use MUMPS for the subproblem solver. > - Then I tried UMFPACK. This works fine when the diagonal blocks (and the > memory required to store the factors) are small but crashes when they are a > little bit larger. For example with a "numeric final size" of 4203.7 MBytes, > I got the following message "ERROR: out of memory" while there was plenty > of memory left in the computer. I tried either with the UMFPACK version 5.2, > downloaded by PETSc, or with a manually installed version 5.4, linked to > PETSc. Is this a behavior from UMFPACK that you already experienced? > Send all the error output. However, in oder to address more than 4G, you will need 64-bit pointers. - Since UMFPACK seemed to have a memory limit around 4096 MB, I tried to > install a PETSc version with the option "--with-64-bit-indices", however > none of the partitioning packages could be compiled with this option > (parmetis,chaco,jostle,party,scotch). Is there a way to compile PETSc with > 64 bit indices AND a partitioning package? > Not that I know of. > - Finally, I tried to modify the PETSc source code umfpack.c so that it > would deal with 64 bit indices, but I only ended up so far with a > segmentation violation message at the execution... Is it the only way I > could use UMPACK with large sparse matrices? > Why not just upgrade to a 64-bit OS if you want to address so much memory on a single machine? Matt > Thank you, > Regards, > francois pacull. > -- What most experimenters take for granted before they begin their experiments is infinitely more interesting than any results to which their experiments lead. -- Norbert Wiener -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20091027/46ec96d7/attachment.htm>
