[petsc-dev] -pc_asm_blocks

[Jed Brown]

I thought this used to work:

$ cd petsc/src/ksp/ksp/examples/tutorials/
$ ./ex2 -pc_type asm -pc_asm_blocks 2
[0]PETSC ERROR: --------------------- Error Message ------------------------------------
[0]PETSC ERROR: Petsc has generated inconsistent data!
[0]PETSC ERROR: Specified ASM subdomain sizes were invalid: 112 != 56!
[0]PETSC ERROR: ------------------------------------------------------------------------
[0]PETSC ERROR: Petsc Development HG revision: c48026146083ef288c8218540e6f61b678c1c226 HG Date: Sun Jan 17 17:16:57 2010 +0100
[0]PETSC ERROR: See docs/changes/index.html for recent updates.
[0]PETSC ERROR: See docs/faq.html for hints about trouble shooting.
[0]PETSC ERROR: See docs/index.html for manual pages.
[0]PETSC ERROR: ------------------------------------------------------------------------
[0]PETSC ERROR: ./ex2 on a ompi named kunyang by jed Mon Jan 18 14:39:15 2010
[0]PETSC ERROR: Libraries linked from /home/jed/petsc/ompi/lib
[0]PETSC ERROR: Configure run at Sun Jan 17 17:20:32 2010
[0]PETSC ERROR: Configure options --with-zoltan-dir=/usr --download-ml --with-blas-lapack-dir=/usr --download-blacs --download-chaco --with-hdf5-dir=/usr --download-mumps --download-superlu_dist --download-spooles --download-sundials --download-hypre --with-c2html --with-mpi-dir=/usr --with-umfpack-dir=/usr --with-parmetis-dir=/usr --download-scalapack --with-lgrind --with-shared --with-sowing -PETSC_ARCH=ompi --download-superlu --download-spai
[0]PETSC ERROR: ------------------------------------------------------------------------
[0]PETSC ERROR: PCSetUp_ASM() line 239 in src/ksp/pc/impls/asm/asm.c
[0]PETSC ERROR: PCSetUp() line 795 in src/ksp/pc/interface/precon.c
[0]PETSC ERROR: KSPSetUp() line 237 in src/ksp/ksp/interface/itfunc.c
[0]PETSC ERROR: KSPSolve() line 353 in src/ksp/ksp/interface/itfunc.c
[0]PETSC ERROR: main() line 196 in src/ksp/ksp/examples/tutorials/ex2.c
--------------------------------------------------------------------------
MPI_ABORT was invoked on rank 0 in communicator MPI_COMM_WORLD 
with errorcode 77.

NOTE: invoking MPI_ABORT causes Open MPI to kill all MPI processes.
You may or may not see output from other processes, depending on
exactly when Open MPI kills them.
--------------------------------------------------------------------------


Looking at the loop that is generating this inconsistency, osm->is_local
is NULL, so we take the second branch for each block:

      if (osm->is_local) {
        ...
      } else {
        ierr = VecGetLocalSize(vec,&m_local);CHKERRQ(ierr);
        osm->y_local[i] = osm->y[i];
        ierr = PetscObjectReference((PetscObject) osm->y[i]);CHKERRQ(ierr);
        osm->prolongation[i] = osm->restriction[i];
        ierr = PetscObjectReference((PetscObject) osm->restriction[i]);CHKERRQ(ierr);
      }

But vec is everything owned by that process so m_local is too big unless
there is only one subdomain.  What was this code supposed to be doing?

Jed