[petsc-dev] proposed minor PetscPartitioner changes

[Fande Kong]

I was wondering what is the conclusion on this?

PetscPartitioner and MatPartitioning, which one will be kept? There is the
code duplication. I am asking because I an working on a hierarchical
 partitioning based MatPartitioning Interface and we also
use MatPartitioning Interface in MOOSE to access all external partitioners.

Just want to make sure I am using the right partitioning interface.

Thanks,

Fande,



On Thu, Dec 7, 2017 at 8:33 AM Matthew Knepley <knepley at gmail.com> wrote:

> 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/312beb00c9b3e1e8ec8fac64a948a1af779da02f/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/ab7d5f43fd87d1d57b51b6e7ff8de0ef3e904673/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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