[petsc-dev] Error on large problems.

[Mark Adams]

On Sat, Mar 7, 2015 at 5:49 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
> > On Mar 7, 2015, at 4:27 PM, Mark Adams <mfadams at lbl.gov> wrote:
> >
> >
> >
> > On Sat, Mar 7, 2015 at 3:11 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:
> >
> >   Hmm,  my first guess is a mixup between PetscMPIInt and PetscInt
> arrays  or MPIU_INT somewhere. (But compilers catch most of these)
> >
> > I have a run with ~9K eq/core 128K cores many times but have never
> gotten the 32K/core (4B eq.) run to work.  So it looks like an int overflow
> issue.
>
>   Well in theory if we have done everything write with 64 bit indices
> there should never be an integer overflow (though of course there could be
> mistake somewhere but generally the compiler will detect if we are trying
> to stick a 64 bit int into a 32 bit slot.
>
>    Can you try the same example without GAMG (say with hypre instead); if
> it goes through ok it might indicate an int issue either in gamg or the
> code that gamg calls?
>
>
Good idea,  Jacobi works.  I will try a stripped down GAMG next.





>   Barry
>
> >
> >
> >   Another possibility is bug in the MPI for many large messages; any
> chance you can run the same thing on a very different system? Mira?
> >
> > Not soon, but I have Chombo and PETSc built on Mira and it would not be
> hard to get this code setup and try it.
> >
> > This is for SCE15 so I will turn the PETSc test off unless someone has
> any ideas on something to try.  I am using maint perhaps I should use
> master.
> >
> > Mark
> >
> >
> >   Barry
> >
> > > On Mar 7, 2015, at 1:21 PM, Mark Adams <mfadams at lbl.gov> wrote:
> > >
> > > I seem to be getting this error on Edison with 128K cores and ~4
> Billion equations.  I've seen this error several time.  I've attached a
> recent output from this.  I wonder if it is an integer overflow.  This
> built with 64 bit integers, but I notice that GAMG prints out N and I see
> N=0 for the finest level.
> > >
> > > Mark
> > > <out.131072.uniform.txt>
> >
> >
>
>
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