[petsc-users] FETI-DP implementation and call sequence

[Jed Brown]

Satish Balay <balay at mcs.anl.gov> writes:
> Perhaps the following is the fix [with proper comments, more error
> checks?]. But someone more familiar with this code should check this..
>
> Satish
>
> --------------
> $ git diff |cat
> diff --git a/src/ksp/pc/impls/is/pcis.c b/src/ksp/pc/impls/is/pcis.c
> index dab5836..0fa0217 100644
> --- a/src/ksp/pc/impls/is/pcis.c
> +++ b/src/ksp/pc/impls/is/pcis.c
> @@ -140,6 +140,8 @@ PetscErrorCode  PCISSetUp(PC pc)
>    ierr = PetscObjectTypeCompare((PetscObject)pc->pmat,MATIS,&flg);CHKERRQ(ierr);
>    if (!flg) SETERRQ(PetscObjectComm((PetscObject)pc),PETSC_ERR_ARG_WRONG,"Preconditioner type of Neumann Neumman requires matrix of type MATIS");
>    matis = (Mat_IS*)pc->pmat->data;
> +  PetscObjectReference((PetscObject)pc->pmat);
> +  pcis->pmat = pc->pmat;

Uh, PCISSetUp can be called more than once?

And simply destroying the pcis->pmat reference is not enough because
that extra reference could significantly increase the peak memory usage.
The right solution is to not hold that reference and not hold the info.

>    pcis->pure_neumann = matis->pure_neumann;
>  
> @@ -378,8 +380,9 @@ PetscErrorCode  PCISDestroy(PC pc)
>    ierr = VecScatterDestroy(&pcis->global_to_B);CHKERRQ(ierr);
>    ierr = PetscFree(pcis->work_N);CHKERRQ(ierr);
>    if (pcis->ISLocalToGlobalMappingGetInfoWasCalled) {
> -    ierr = ISLocalToGlobalMappingRestoreInfo((ISLocalToGlobalMapping)0,&(pcis->n_neigh),&(pcis->neigh),&(pcis->n_shared),&(pcis->shared));CHKERRQ(ierr);
> +    ierr = ISLocalToGlobalMappingRestoreInfo(((Mat_IS*)pcis->pmat->data)->mapping,&(pcis->n_neigh),&(pcis->neigh),&(pcis->n_shared),&(pcis->shared));CHKERRQ(ierr);
>    }

Why not restore the info at the place it is gotten, like we do with
every other accessor?

> +  ierr = MatDestroy(&pcis->pmat);CHKERRQ(ierr);
>    ierr = PetscObjectComposeFunction((PetscObject)pc,"PCISSetUseStiffnessScaling_C",NULL);CHKERRQ(ierr);
>    ierr = PetscObjectComposeFunction((PetscObject)pc,"PCISSetSubdomainScalingFactor_C",NULL);CHKERRQ(ierr);
>    ierr = PetscObjectComposeFunction((PetscObject)pc,"PCISSetSubdomainDiagonalScaling_C",NULL);CHKERRQ(ierr);
> diff --git a/src/ksp/pc/impls/is/pcis.h b/src/ksp/pc/impls/is/pcis.h
> index 4a42cf9..736ea8c 100644
> --- a/src/ksp/pc/impls/is/pcis.h
> +++ b/src/ksp/pc/impls/is/pcis.h
> @@ -73,6 +73,7 @@ typedef struct {
>    /* We need:                                                                                 */
>    /* proc[k].loc_to_glob(proc[k].shared[i][m]) == proc[l].loc_to_glob(proc[l].shared[j][m])   */
>    /* for all 0 <= m < proc[k].n_shared[i], or equiv'ly, for all 0 <= m < proc[l].n_shared[j]  */
> +  Mat pmat;
>  } PC_IS;
>  
>  PETSC_EXTERN PetscErrorCode PCISSetUp(PC pc);

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