[petsc-dev] petsc-dev post from tabrezali at gmail.com requires approval

[Matthew Knepley]

On Tue, Aug 27, 2019 at 4:11 AM Lisandro Dalcin <dalcinl at gmail.com> wrote:

> On Mon, 26 Aug 2019 at 21:26, Smith, Barry F. <bsmith at mcs.anl.gov> wrote:
>
>>
>>
>> > On Aug 26, 2019, at 10:11 AM, Lisandro Dalcin <dalcinl at gmail.com>
>> wrote:
>> >
>> >
>> >
>> > On Sun, 25 Aug 2019 at 18:37, Smith, Barry F. via petsc-dev <
>> petsc-dev at mcs.anl.gov> wrote:
>> >
>> >    Metis is installed.
>> >
>> > config/PETSc/Configure.py:
>> self.addDefine('HAVE_'+i.PACKAGE.replace('-','_'), 1)  # ONLY list package
>> if it is used directly by PETSc (and not only by another package)
>> >
>> >     Since metis is not used by PETSc we don't set the PETSC_HAVE_METIS
>> flag because PETSc doesn't need it.
>> >
>> >
>> > This is not true, in DMPlex we have an explicit call to
>> METIS_PartGraphKway(). Of course, this code is protected with just
>> HAVE_PARMETIS, because if you have parmetis, then you have metis.
>>
>>    Hmm, I think is should be protected with HAVE_METIS. There is nothing
>> that says PETSc can only be built with metis plus parmetis; it could be
>> built with just metis.
>>
>>
> Sorry, maybe I was not clear enough.
>
> The DMPlex code I'm talkinga about uses both ParMETIS and METIS, depending
> on the input graph being sequential or parallel.
>
> https://gitlab.com/petsc/petsc/blob/master/src/dm/impls/plex/plexpartition.c#L1799
> So this code requires ParMETIS, and if you have it, then you have METIS,
> the a HAVE_METIS check seems a bit redundant to me.
> Do you still think we should change it?
>
> Or maybe we should use `#if defined(PETSC_HAVE_METIS) &&
> defined(PETSC_HAVE_PARMETIS)`?
>
> Anything to add, Matthew?
>

1) I think we turn on PETSC_HAVE_METIS

2) I think we leave the guard as PARMETIS since we need it for the parallel
case and it implies Metis

  Thanks,

    Matt


> PS: In any case, I think configure should emit PETSC_HAVE_METIS, we are
> really using it.
>
> --
> Lisandro Dalcin
> ============
> Research Scientist
> Extreme Computing Research Center (ECRC)
> King Abdullah University of Science and Technology (KAUST)
> http://ecrc.kaust.edu.sa/
>


-- 
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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