[petsc-users] Freeing Preconditioner Matrix Space (Again)

[Gaetan Kenway]

Hello

I've managed to get the c-function for freeing preconditioner memory
written. The contents of my new 'pcasmfreespace.c' is below:

#include <private/pcimpl.h>     /*I "petscpc.h" I*/

typedef struct {
 PetscInt   n, n_local, n_local_true;
 PetscInt   overlap;             /* overlap requested by user */
 KSP        *ksp;                /* linear solvers for each block */
 VecScatter *restriction;        /* mapping from global to subregion */
 VecScatter *localization;       /* mapping from overlapping to
non-overlapping subregion */
 VecScatter *prolongation;       /* mapping from subregion to global */
 Vec        *x,*y,*y_local;      /* work vectors */
 IS         *is;                 /* index set that defines each overlapping
subdomain */
 IS         *is_local;           /* index set that defines each
non-overlapping subdomain, may be NULL */
 Mat        *mat,*pmat;          /* mat is not currently used */
 PCASMType  type;                /* use reduced interpolation, restriction
or both */
 PetscInt  type_set;            /* if user set this value (so won't change
it for symmetric problems) */
 PetscInt  same_local_solves;   /* flag indicating whether all local solvers
are same */
 PetscInt  sort_indices;        /* flag to sort subdomain indices */
} PC_ASM;

void pcasmfreespace_(PC pc)
    {

      PC_ASM         *osm = (PC_ASM*)pc->data;
      PetscErrorCode ierr;

      if (osm->pmat) {
    if (osm->n_local_true > 0) {
      ierr = MatDestroyMatrices(osm->n_local_true,&osm->pmat);CHKERRQ(ierr);
    }
    osm->pmat = 0;
      }

      if (pc->pmat) {ierr = MatDestroy(pc->pmat);CHKERRQ(ierr); pc->pmat =
0;}

    }

Note the underscore as I'm trying to call it from Fortran. When I call it
from fortran, I use:

call pcasmfreespace(global_pc)

This calls, the function, ok, but (according to Valgrind) I have an invalid
read on the line containing:

if (osm->pmat){

I suspect this is something to do with passing the fortran "pointer" of the
PC to c, or something along this lines. Is there anything else special you
have to do to pass the "fortran" petsc objects to c?

Thanks

Gaetan


Message: 2
Date: Sun, 21 Aug 2011 17:22:28 -0500
From: Barry Smith <bsmith at mcs.anl.gov>
Subject: Re: [petsc-users] Freeing Preconditioner Matrix Space
To: PETSc users list <petsc-users at mcs.anl.gov>
Message-ID: <953121EF-B6AC-42EE-87BE-D4402C121652 at mcs.anl.gov>
Content-Type: text/plain; charset=us-ascii


 You don't need to put that in the PETSc source. Just built it in the same
directory you build your application and link it in like any of your
application code. You will need to stick
#include <private/pcimpl.h>     /*I "petscpc.h" I*/

typedef struct {
 PetscInt   n, n_local, n_local_true;
 PetscInt   overlap;             /* overlap requested by user */
 KSP        *ksp;                /* linear solvers for each block */
 VecScatter *restriction;        /* mapping from global to subregion */
 VecScatter *localization;       /* mapping from overlapping to
non-overlapping subregion */
 VecScatter *prolongation;       /* mapping from subregion to global */
 Vec        *x,*y,*y_local;      /* work vectors */
 IS         *is;                 /* index set that defines each overlapping
subdomain */
 IS         *is_local;           /* index set that defines each
non-overlapping subdomain, may be NULL */
 Mat        *mat,*pmat;          /* mat is not currently used */
 PCASMType  type;                /* use reduced interpolation, restriction
or both */
 PetscBool  type_set;            /* if user set this value (so won't change
it for symmetric problems) */
 PetscBool  same_local_solves;   /* flag indicating whether all local
solvers are same */
 PetscBool  sort_indices;        /* flag to sort subdomain indices */
} PC_ASM;

before the subroutine.

 Barry

On Aug 21, 2011, at 3:24 PM, Gaetan Kenway wrote:

> Hello
>
> I am attempting to implement a "hack" that was posted on the list a while
back. I'm working with the adjoint linear system solver for a CFD solver.
I'm using the ASM (or Block Jacobi) preconditioner with ILU(p) on each of
the sub-domains. I use a different Preconditioner matrix (Pmat) than the
actual jacobian. What I want to do is destroy the Pmat memory after the ILU
factorization is performed. The hack that was posted is copied below:
>  PCASMFreeSpace(PC pc)
>    {
>   PC_ASM         *osm = (PC_ASM*)pc->data;
>   PetscErrorCode ierr;
>
>      if (osm->pmat) {
>     if (osm->n_local_true > 0) {
>
>       ierr = MatDestroyMatrices(osm->n_
local_true,&osm->pmat);CHKERRQ(ierr);
>     }
>   osm->pmat = 0;
>   }
>   if (pc->pmat) {ierr = MatDestroy(pc->pmat);CHKERRQ(ierr); pc->pmat = 0;}
>
>   return 0;
>  }
>
> However, I've had no luck actually getting the function compiled into
petsc. There are no erorrs reported with i type "make" in the asm directory,
but when I try to use the function in my application it can't find the
symbol while linking. Where does it go in the asm.c file? Does it use
"static PetscErrorCode" or "PetscErrorCode PETSCKSP_DLLEXPORT"? Does it have
to be added to the .h include files? What has to be done for it work with
Fortran?
>
> Any suggestions would be greatly appreciated.  This represents a
significant chunk of my application's memory (10%-30%) and as such its too
much to ignore.   Also is there any chance something like this would make it
into an actual PETSc release?
>
> Gaetan
>
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