[Trilinos-Users] Best practices for parallel solutions?

[Paul Dionne]

I'd like to know the recommended practice for solving parallel linear systems.  I have an implicit finite-volume solver and thus I have ghost cell links during assembly.  I found a presentation entitled "HerouxEpetraConcepts.pptx" that suggested using an assembly map and a solver map.  After assembly, the following commands were given in the presentation:

Epetra_Export Exporter(AssemblyMap, SolverMap);
Epetra_CrsMatrix SolverMatrix(Copy, SolverMap, 0);
SolverMatrix.Export(AssemblyMatrix, Exporter, Add);
SolverMatrix.FillComplete();

My problems are nonlinear so I solve the linear system several times each time step.  Thus, I was wondering about the efficiency and memory requirements of having 2 matrices and performing this matrix copy each time I solve.

Is this the current recommended practice?

I'd also like to know how best to get the ghost cell values after the solution (without doing it myself through MPI).  I'm trying to get it to work using Epetra_Export but not having much luck.

Thanks for any assistance.