[petsc-users] Local columns of A10 do not equal local rows of A00
Alexander Lindsay
alexlindsay239 at gmail.com
Mon Nov 7 16:47:59 CST 2022
My understanding looking at PCFieldSplitSetDefaults is that our
implementation of `createfielddecomposition` should get called, we'll set
`fields` and then (ignoring possible user setting of
-pc_fieldsplit_%D_fields flag) PCFieldSplitSetIS will get called with
whatever we did to `fields`. So yea I guess that just looking over that I
would assume we're not supplying two different index sets for rows and
columns, or put more precisely we (MOOSE) are not really afforded the
opportunity to. But my interpretation could very well be wrong.
On Mon, Nov 7, 2022 at 12:33 PM Matthew Knepley <knepley at gmail.com> wrote:
> On Mon, Nov 7, 2022 at 2:09 PM Alexander Lindsay <alexlindsay239 at gmail.com>
> wrote:
>
>> The libMesh/MOOSE specific code that identifies dof indices for
>> ISCreateGeneral is in DMooseGetEmbedding_Private. I can share that function
>> (it's quite long) or more details if that could be helpful.
>>
>
> Sorry, I should have written more. The puzzling thing for me is that
> somehow it looks like the row and column index sets are not the same. I did
> not think
> PCFIELDSPLIT could do that. The PCFieldSplitSetIS() interface does not
> allow it. I was wondering how you were setting the ISes.
>
> Thanks,
>
> Matt
>
>
>> On Mon, Nov 7, 2022 at 10:55 AM Alexander Lindsay <
>> alexlindsay239 at gmail.com> wrote:
>>
>>> I'm not sure exactly what you mean, but I'll try to give more details.
>>> We have our own DM class (DM_Moose) and we set our own field and domain
>>> decomposition routines:
>>>
>>> dm->ops->createfielddecomposition = DMCreateFieldDecomposition_Moose;
>>>
>>> dm->ops->createdomaindecomposition =
>>> DMCreateDomainDecomposition_Moose;
>>>
>>>
>>> The field and domain decomposition routines are as follows (can see also
>>> at
>>> https://github.com/idaholab/moose/blob/next/framework/src/utils/PetscDMMoose.C
>>> ):
>>>
>>> static PetscErrorCode
>>> DMCreateFieldDecomposition_Moose(
>>> DM dm, PetscInt * len, char *** namelist, IS ** islist, DM ** dmlist)
>>> {
>>> PetscErrorCode ierr;
>>> DM_Moose * dmm = (DM_Moose *)(dm->data);
>>>
>>> PetscFunctionBegin;
>>> /* Only called after DMSetUp(). */
>>> if (!dmm->_splitlocs)
>>> PetscFunctionReturn(0);
>>> *len = dmm->_splitlocs->size();
>>> if (namelist)
>>> {
>>> ierr = PetscMalloc(*len * sizeof(char *), namelist);
>>> CHKERRQ(ierr);
>>> }
>>> if (islist)
>>> {
>>> ierr = PetscMalloc(*len * sizeof(IS), islist);
>>> CHKERRQ(ierr);
>>> }
>>> if (dmlist)
>>> {
>>> ierr = PetscMalloc(*len * sizeof(DM), dmlist);
>>> CHKERRQ(ierr);
>>> }
>>> for (const auto & dit : *(dmm->_splitlocs))
>>> {
>>> unsigned int d = dit.second;
>>> std::string dname = dit.first;
>>> DM_Moose::SplitInfo & dinfo = (*dmm->_splits)[dname];
>>> if (!dinfo._dm)
>>> {
>>> ierr = DMCreateMoose(((PetscObject)dm)->comm, *dmm->_nl,
>>> &dinfo._dm);
>>> CHKERRQ(ierr);
>>> ierr = PetscObjectSetOptionsPrefix((PetscObject)dinfo._dm,
>>> ((PetscObject)dm)->prefix);
>>> CHKERRQ(ierr);
>>> std::string suffix = std::string("fieldsplit_") + dname + "_";
>>> ierr = PetscObjectAppendOptionsPrefix((PetscObject)dinfo._dm,
>>> suffix.c_str());
>>> CHKERRQ(ierr);
>>> }
>>> ierr = DMSetFromOptions(dinfo._dm);
>>> CHKERRQ(ierr);
>>> ierr = DMSetUp(dinfo._dm);
>>> CHKERRQ(ierr);
>>> if (namelist)
>>> {
>>> ierr = PetscStrallocpy(dname.c_str(), (*namelist) + d);
>>> CHKERRQ(ierr);
>>> }
>>> if (islist)
>>> {
>>> if (!dinfo._rembedding)
>>> {
>>> IS dembedding, lembedding;
>>> ierr = DMMooseGetEmbedding_Private(dinfo._dm, &dembedding);
>>> CHKERRQ(ierr);
>>> if (dmm->_embedding)
>>> {
>>> // Create a relative embedding into the parent's index space.
>>> ierr = ISEmbed(dembedding, dmm->_embedding, PETSC_TRUE,
>>> &lembedding);
>>> CHKERRQ(ierr);
>>> const PetscInt * lindices;
>>> PetscInt len, dlen, llen, *rindices, off, i;
>>> ierr = ISGetLocalSize(dembedding, &dlen);
>>> CHKERRQ(ierr);
>>> ierr = ISGetLocalSize(lembedding, &llen);
>>> CHKERRQ(ierr);
>>> if (llen != dlen)
>>> SETERRQ1(((PetscObject)dm)->comm, PETSC_ERR_PLIB, "Failed to
>>> embed split %D", d);
>>> ierr = ISDestroy(&dembedding);
>>> CHKERRQ(ierr);
>>> // Convert local embedding to global (but still relative)
>>> embedding
>>> ierr = PetscMalloc(llen * sizeof(PetscInt), &rindices);
>>> CHKERRQ(ierr);
>>> ierr = ISGetIndices(lembedding, &lindices);
>>> CHKERRQ(ierr);
>>> ierr = PetscMemcpy(rindices, lindices, llen *
>>> sizeof(PetscInt));
>>> CHKERRQ(ierr);
>>> ierr = ISDestroy(&lembedding);
>>> CHKERRQ(ierr);
>>> // We could get the index offset from a corresponding global
>>> vector, but subDMs don't yet
>>> // have global vectors
>>> ierr = ISGetLocalSize(dmm->_embedding, &len);
>>> CHKERRQ(ierr);
>>>
>>> ierr = MPI_Scan(&len,
>>> &off,
>>> 1,
>>> #ifdef PETSC_USE_64BIT_INDICES
>>> MPI_LONG_LONG_INT,
>>> #else
>>> MPI_INT,
>>> #endif
>>> MPI_SUM,
>>> ((PetscObject)dm)->comm);
>>> CHKERRQ(ierr);
>>>
>>> off -= len;
>>> for (i = 0; i < llen; ++i)
>>> rindices[i] += off;
>>> ierr = ISCreateGeneral(
>>> ((PetscObject)dm)->comm, llen, rindices,
>>> PETSC_OWN_POINTER, &(dinfo._rembedding));
>>> CHKERRQ(ierr);
>>> }
>>> else
>>> {
>>> dinfo._rembedding = dembedding;
>>> }
>>> }
>>> ierr = PetscObjectReference((PetscObject)(dinfo._rembedding));
>>> CHKERRQ(ierr);
>>> (*islist)[d] = dinfo._rembedding;
>>> }
>>> if (dmlist)
>>> {
>>> ierr = PetscObjectReference((PetscObject)dinfo._dm);
>>> CHKERRQ(ierr);
>>> (*dmlist)[d] = dinfo._dm;
>>> }
>>> }
>>> PetscFunctionReturn(0);
>>> }
>>>
>>> static PetscErrorCode
>>> DMCreateDomainDecomposition_Moose(
>>> DM dm, PetscInt * len, char *** namelist, IS ** innerislist, IS **
>>> outerislist, DM ** dmlist)
>>> {
>>> PetscErrorCode ierr;
>>>
>>> PetscFunctionBegin;
>>> /* Use DMCreateFieldDecomposition_Moose() to obtain everything but
>>> outerislist, which is currently
>>> * PETSC_NULL. */
>>> if (outerislist)
>>> *outerislist = PETSC_NULL; /* FIX: allow mesh-based overlap. */
>>> ierr = DMCreateFieldDecomposition_Moose(dm, len, namelist,
>>> innerislist, dmlist);
>>> CHKERRQ(ierr);
>>> PetscFunctionReturn(0);
>>> }
>>>
>>>
>>>
>>> On Thu, Nov 3, 2022 at 5:19 PM Matthew Knepley <knepley at gmail.com>
>>> wrote:
>>>
>>>> On Thu, Nov 3, 2022 at 7:52 PM Alexander Lindsay <
>>>> alexlindsay239 at gmail.com> wrote:
>>>>
>>>>> I have errors on quite a few (but not all) processes of the like
>>>>>
>>>>> [1]PETSC ERROR: --------------------- Error Message
>>>>> --------------------------------------------------------------
>>>>> [1]PETSC ERROR: Nonconforming object sizes
>>>>> [1]PETSC ERROR: Local columns of A10 4137 do not equal local rows of
>>>>> A00 4129
>>>>>
>>>>> when performing field splits. We (MOOSE) have some code for
>>>>> identifying the index sets for each split. However, the code was written by
>>>>> some authors who are no longer with us. Normally I would chase this down in
>>>>> a debugger, but this error only seems to crop up for pretty complex and
>>>>> large meshes. If anyone has an idea for what we might be doing wrong, that
>>>>> might help me chase this down faster. I guess intuitively I'm pretty
>>>>> perplexed that we could get ourselves into this pickle as it almost appears
>>>>> that we have two different local dof index counts for a given block (0 in
>>>>> this case). More background, if helpful, can be found in
>>>>> https://github.com/idaholab/moose/issues/22359 as well as
>>>>> https://github.com/idaholab/moose/discussions/22468.
>>>>>
>>>>
>>>> How are you specifying the blocks? I would not have thought this was
>>>> possible.
>>>>
>>>> Thanks,
>>>>
>>>> Matt
>>>>
>>>>
>>>>> I should note that we are currently running with 3.16.6 as our PETSc
>>>>> submodule hash (we are talking about updating to 3.18 soon).
>>>>>
>>>>
>>>>
>>>> --
>>>> What most experimenters take for granted before they begin their
>>>> experiments is infinitely more interesting than any results to which their
>>>> experiments lead.
>>>> -- Norbert Wiener
>>>>
>>>> https://www.cse.buffalo.edu/~knepley/
>>>> <http://www.cse.buffalo.edu/~knepley/>
>>>>
>>>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which their
> experiments lead.
> -- Norbert Wiener
>
> https://www.cse.buffalo.edu/~knepley/
> <http://www.cse.buffalo.edu/~knepley/>
>
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