[petsc-dev] trying to make MKL work with GAMG

[Mark Adams]

"-mat_seqaij_type seqaijmkl" just worked.

On Wed, Jul 4, 2018 at 9:44 AM Mark Adams <mfadams at lbl.gov> wrote:

>
>
> On Wed, Jul 4, 2018 at 3:01 AM Richard Tran Mills <rtmills at anl.gov> wrote:
>
>> Hi Mark,
>>
>> I'd never looked at the code for MatCreateMPIAIJWithSeqAIJ(), but it
>> looks like if you are using MPIAIJ matrices but you've set
>> "-mat_seqaij_type seqaijmkl",
>>
>
> No, I am using -mat_type aijmkl
>
>
>> then the "diagonal" portion of the MPIAIJ matrix ends up as a SEQAIJMKL
>> instance, but the off-diagonal portion ends up as a plain SEQAIJ when it is
>> created with MatCreateSeqAIJWithArrays(). (I have not stepped through this
>> with a debugger to verify that this is actually what happens.) So, if we
>> want the off-diagonal matrix to also be a SEQAIJMKL, then we either need to
>> add some logic after the MatCreateSeqAIJWithArrays() call to check to see
>> if a different subtype of SEQAIJ is being used and then convert it to the
>> correct type, or we need a variant of MatCreateSeqAIJWithArrays() that will
>> honor the subtype of SEQAIJ that we are using. Barry, since you added the
>> concept of subtyping for SEQAIJ, what do you prefer?
>>
>> No preference.
>
>
>> I note that in some (most?) cases, I think we are OK or even better off
>> with the off-diagonal matrix in the MPIAIJ not being a SEQAIJMKL one,
>> because the PETSc routines can used the "compressed row" stuff to speed up
>> handling the many zero rows that often end up in the off-diagonal, whereas
>> the MKL routines cannot.
>>
>>
> OK , I'll keep that in mind. I pushed a branch with fixes to get my gamg
> tests working (ksp ex56 primarily). I'm going to make a new branch and try "-mat_seqaij_type
> seqaijmkl".
>
> Thanks,
> Mark
>
>
>> --Richard
>>
>> On Tue, Jul 3, 2018 at 4:31 PM, Mark Adams <mfadams at lbl.gov> wrote:
>>
>>> I have having to fix AIJ methods that don't get the type from the args
>>> to set created matrix type, so as to keep the MKL typing.
>>>
>>> I am not sure how to fix this because I don't know to say 'make MPI from
>>> SEQ' in this method
>>>
>>> PetscErrorCode MatCreateMPIAIJWithSeqAIJ(MPI_Comm comm,Mat A,Mat B,const
>>> PetscInt garray[],Mat *mat)
>>> {
>>>  ....
>>>   ierr = MatCreate(comm,mat);CHKERRQ(ierr);
>>>   ierr = MatGetSize(A,&m,&n);CHKERRQ(ierr);
>>> ....
>>>   ierr = MatSetSizes(*mat,m,n,PETSC_DECIDE,N);CHKERRQ(ierr);
>>>   ierr = MatSetType(*mat,MATMPIAIJ);CHKERRQ(ierr);
>>>
>>> How should I do this?  Other places in the code I get the type from
>>> input (MPI) args and set created matrix types accordingly. I could just put
>>> a switch with an error for any new types that might come along in the
>>> future ...
>>>
>>> Mark
>>>
>>
>>
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