Multiple communicators

[Matthew Knepley]

On Tue, Nov 24, 2009 at 7:13 PM, <irfan.khan at gatech.edu> wrote:

> I use seperete communicators for fluid and solid ranks in a fluid-structure
> interaction code. I use PETSc tools (KSP) to solve for the solid phase (FEA)
> which is carried out under a different communicator (FEA_Comm).
>
> Unless I am doing something wrong, I have found that the command line
> options: -ksp_type; -mat_partitioning_type, don't work if there are 2
> communicators. But for single communicator they work. Please see the
> attached files containing output of -log_summary for 2 different codes
> (scroll down to the end). One with single communicator and the other with
> two communicators. Both the output have been generated with the same PETSc
> compilation.
>
> Futher -log_summary results are not able to detect all the events that have
> been registered if they are not in the WORLD communicator.
>

I am not sure what you are doing, but something is wrong in this code. Using
different communicators does not
have much to do with options. Any object (like a KSP) can be created using a
subcomm of WORLD. Are you
setting PETSC_COMM_WORLD to something different? That is not necessary here.

  Matt


> Thank you
> Irfan
>
> ----- Original Message -----
> From: "Matthew Knepley" <knepley at gmail.com>
> To: "PETSc users list" <petsc-users at mcs.anl.gov>
> Sent: Tuesday, November 24, 2009 8:03:00 PM GMT -05:00 US/Canada Eastern
> Subject: Re: Multiple communicators
>
> On Tue, Nov 24, 2009 at 6:59 PM, <irfan.khan at gatech.edu> wrote:
>
>> Hello
>>
>> Does the procedure for providing command line options and to obtain
>> profiling data through -log_summary change if there are multiple MPI
>> communicators in a petsc code?
>>
>
> There is always WORLD, so it should be fine unless I misunderstand your
> question.
>
>   Matt
>
>
>> If so, can somebody point me to information, references on how to provide
>> command line options if there are multiple communicators?
>>
>> Thank you
>> Irfan
>>
>> --
>> PhD Candidate
>> G.W. Woodruff School of Mechanical Engineering
>> Georgia Institute of Technology
>> Atlanta, GA (30332)
>>
>
>
>
> --
> 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
>
>
> --
> PhD Candidate
> G.W. Woodruff School of Mechanical Engineering
> Georgia Institute of Technology
> Atlanta, GA (30332)
>



-- 
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
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