Hi, It seems to me that you have misunderstood the usage of Petsc's MatXSetPreallocation. With a 27 point stencil, the "total" number of non-zeros in a row must be 27. You need to split this up into those interactions that are local and those that are off-proc. Setting off-proc nnz to be 27 is way too high. You are running out of memory.
Mrinal On Sat, Feb 23, 2013 at 4:09 AM, Hui Zhang <mike.hui.zhang at hotmail.com>wrote: > No, it is a 27-stencil discretization. I use petsc MatXSetPreallocation > with much larger estimates for off-diagonal (i.e. on other processors) > zeros. Basically, I say 27 non-zeros per row are on other processors. > Does this cause the MUMPS error? Thanks a lot! > > On Feb 23, 2013, at 9:56 AM, paresh murthy wrote: > > > Hello Mike, > > > > I would guess, as perhaps others might as well, that it is trying to > solve a million x million dense matrix. > > Are you sure you have removed the zeroes and given it a sparse matrix ? > > > > Paresh > > > > > > From: Hui Zhang <mike.hui.zhang at hotmail.com> > > To: mumps-users at listes.ens-lyon.fr; PETSc users list < > petsc-users at mcs.anl.gov> > > Cc: Hui Zhang <mike.hui.zhang at hotmail.com> > > Sent: Saturday, February 23, 2013 9:51 AM > > Subject: [mumps-users] MUMPS error > > > > Error reported by MUMPS in numerical factorization phase: Cannot > allocate required memory 70397575 megabytes > > > > The required memory is too large. Is that normal? I'm solving a > Helmholtz equation on 100^3 mesh partitioned to 4^3 processors. > > > > > > > > > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20130223/4fb5776c/attachment.html>
