[petsc-users] Problem with solving Poisson eqn for some cases

[Matthew Knepley]

On Thu, Mar 15, 2018 at 3:51 PM, TAY wee-beng <zonexo at gmail.com> wrote:

> Hi,
>
> I'm running a CFD code which solves the momentum and Poisson eqns.
>
> Due to poor scaling with HYPRE at higher cpu no., I decided to try using
> PETSc with boomeramg and gamg.
>
> I tested for some small cases and it work well. However, for the large
> problem which has poor scaling, it gives an error when I change my Poisson
> solver from pure HYPRE to PETSc with boomeramg and gamg.
>
> The error is :
>
> Caught signal number 11 SEGV: Segmentation Violation, probably memory
> access out of range
>
> I tried using:
>
> -poisson_ksp_type richardson -poisson_pc_type hypre -poisson_pc_type_hypre
> boomeramg
>
> -poisson_ksp_type gmres -poisson_pc_type hypre -poisson_pc_type_hypre
> boomeramg
>
> -poisson_pc_type gamg -poisson_pc_gamg_agg_nsmooths 1
>
> but they all gave similar error.
>
> So why is this so? How should I troubleshoot? I am now running a debug ver
> of PETSc to check the error msg.


1) For anything like this, we would like to see a stack trace from the
debugger or valgrind output.

2) We do have several Poisson examples. Does it fail for you on those?

3) You can also try ML, which is the same type of MG as GAMG.
(--download-ml).

  Thanks,

     Matt


>
> --
> Thank you very much.
>
> Yours sincerely,
>
> ================================================
> TAY Wee-Beng (Zheng Weiming) 郑伟明
> Personal research webpage: http://tayweebeng.wixsite.com/website
> Youtube research showcase: https://www.youtube.com/channe
> l/UC72ZHtvQNMpNs2uRTSToiLA
> linkedin: www.linkedin.com/in/tay-weebeng
> ================================================
>
>


-- 
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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