[petsc-dev] proposed minor PetscPartitioner changes

[Matthew Knepley]

On Thu, Dec 7, 2017 at 10:26 AM, Vaclav Hapla <vaclav.hapla at erdw.ethz.ch>
wrote:

>
>
> > 9. 11. 2017 v 12:53, Matthew Knepley <knepley at gmail.com>:
> >
> > I think I need to create a proof-of-concept. I would start by employing
> MatPartitioning in PetscPartitionerPartition with anything outside of this
> function untouched for now (as already suggested in #192), if you agree.
> >
> > Or what about implementing a special temporary PetscPartitioner
> implementation wrapping MatPartitioning?
> > PETSCPARTITIONERMATPARTITIONING sounds crazy, though :) But could be a
> good starting point.
> >
> > This is probably easier, and allows nice regression testing, namely run
> all tests using EXTRA_OPTIONS="-petscparitioner_type matpartitioning". I
> think
> > that should be alright for correctness. There are some parallel
> redistribution tests in Plex.
> >
> > We will need at least one performance regression. Look at how I do it
> here:
> >
> >   https://bitbucket.org/petsc/petsc/src/312beb00c9b3e1e8ec8fac64a948a1
> af779da02f/src/dm/impls/plex/examples/tests/ex9.c?at=
> master&fileviewer=file-view-default
> >
> > You can make custom events, directly access the times, and compare. You
> could run the two versions
> > and check for degradation for a sequence of meshes in parallel.
> >
> >   Thanks,
> >
> >      Matt
>
> I have made some progress in this, see https://bitbucket.org/haplav/
> petsc/branch/haplav/feature-petscpartitionermatpartitioning
> There's a new test ex23 which shows basically that
>   -petscparitioner_type parmetis
> and
>   -petscparitioner_type matpartitioning -mat_partitioning_type parmetis
> give exactly the same results.
>
> I have not created a PR yet since the regression testing you propose fails
> in some cases. When running
>   make -f gmakefile.test test EXTRA_OPTIONS="-petscpartitioner_type
> matpartitioning -options_left 0" search='dm_impls_plex_tests%'
> it seems majority of tests pass but e.g. dm_impls_plex_tests-ex7_7 fails
> since its reference output has been saved for -petscpartitioner_type
> simple. How to deal with that, please?
>

Ignore the ones with simple. I think all the SNES tests are now simple, so
for ex12, ex62, and ex77 can you just do a few runs
and confirm that both ways give the same results?

  Thanks,

     Matt


> As can be seen in my PetscPartitionerPartition_MatPartitioning, the
> needed manipulations with IS are slightly more complicated than what I
> inferred from the Jed's comments. But still just the existing IS methods
> suffice. See bitbucket.org/haplav/petsc/src/ab7d5f43fd87d1d57b51b6e7ff8de0
> ef3e904673/src/dm/impls/plex/petscpartmatpart.c?at=haplav%2Ffeature-
> petscpartitionermatpartitioning#petscpartmatpart.c-92
>
> Vaclav




-- 
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.caam.rice.edu/~mk51/>
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