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

[Lisandro Dalcin]

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?

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/
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