[petsc-users] A bad commit affects MOOSE

[Derek Gaston]

On Tue, Apr 3, 2018 at 10:31 AM Satish Balay <balay at mcs.anl.gov> wrote:

> On Tue, 3 Apr 2018, Derek Gaston wrote:
> > Which does bring up a point: I have been able to do solves before with
> > ~50,000 separate PETSc solves without issue.  Is it because I was working
> > with MVAPICH on a cluster?  Does it just have a higher limit?
>
> Don't know - but thats easy to find out with a simple test code..
>

I get 2044 using mvapich on my cluster too.

The only thing I can think of as to why those massive problems work for me
is that any one MPI process is not involved in more than ~2000 processors
(because the communicators are split as you go down the hierarchy).  At
most, a single MPI process will see ~hundreds of PETSc solves but not
thousands.

That said: it's just because of the current nature of the solves I'm doing
- it's definitely possible to have that not be the case with MOOSE.

Derek
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