[petsc-users] CG+GAMG convergence issues in GHEP Krylov-Schur for some MPI runs

Mark Adams mfadams at lbl.gov
Tue Nov 3 07:47:39 CST 2015


BTW, I think that our advice for segv is use a debugger.  DDT or Totalview,
and gdb if need be, will get you right to the source code and will get 90%
of bugs diagnosed.  Valgrind is noisy and cumbersome to use but can
diagnose 90% of the other 10%.

On Tue, Nov 3, 2015 at 7:32 AM, Denis Davydov <davydden at gmail.com> wrote:

> Hi Jose,
>
> > On 3 Nov 2015, at 12:20, Jose E. Roman <jroman at dsic.upv.es> wrote:
> >
> > I am answering the SLEPc-related questions:
> > - Having different number of iterations when changing the number of
> processes is normal.
> the change in iterations i mentioned are for different preconditioners,
> but the same number of MPI processes.
>
>
> > - Yes, if you do not destroy the EPS solver, then the preconditioner
> would be reused.
> >
> > Regarding the segmentation fault, I have no clue. Not sure if this is
> related to GAMG or not. Maybe running under valgrind could provide more
> information.
> will try that.
>
> Denis.
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