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

[TAY wee-beng]

On 15/3/2018 6:21 PM, Matthew Knepley wrote:
> On Thu, Mar 15, 2018 at 3:51 PM, TAY wee-beng <zonexo at gmail.com 
> <mailto: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?
Hi,

Can you recommend me some suitable egs? Esp in Fortran?
>
> 3) You can also try ML, which is the same type of MG as GAMG. 
> (--download-ml).
>
My cluster can't connect to the internet. Where can I 1st download it?

Similarly, how can I find out the location of the ext software by myself?
>   Thanks,
>
>      Matt
>
>
>     -- 
>     Thank you very much.
>
>     Yours sincerely,
>
>     ================================================
>     TAY Wee-Beng (Zheng Weiming) 郑伟明
>     Personal research webpage: http://tayweebeng.wixsite.com/website
>     <http://tayweebeng.wixsite.com/website>
>     Youtube research showcase:
>     https://www.youtube.com/channel/UC72ZHtvQNMpNs2uRTSToiLA
>     <https://www.youtube.com/channel/UC72ZHtvQNMpNs2uRTSToiLA>
>     linkedin: www.linkedin.com/in/tay-weebeng
>     <http://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/%7Emk51/>

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