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

[Mark Adams]

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.
>

Did hypre segv?

In addition to what Matt said, given that this error only occurs on large
runs, you can also try

1) test a debug version. This can sometimes give more info like a stack
trace.

2) If you can't get a stack trace, try running with -poisson_pc_type
jacobi. This is a dead simple solver.


>
> So why is this so? How should I troubleshoot? I am now running a debug ver
> of PETSc to check the error msg.
>
>
>
> --
> 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
> ================================================
>
>
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