GMRES performance

[Matthew Knepley]

On Tue, Oct 20, 2009 at 9:52 AM, <jarunan at ascomp.ch> wrote:

> Hello,
>
> I would like to know some information about GMRES performance in PETSc if
> you have any experience.
>
> I am running a parallel test case(9300 cells) comparing cpu time using by
> solvers in Petsc. While BICGSTAB was doing 0.9 sec, GMRES 15 sec with the
> same preconditioner(Additive Schwarz). I did not expect that GMRES would be
> that much slower. Everything is default.
>

I ssume you mean it takes many more iterates. This is certainly possible.


> Please share your experiences, how the performance of solvers are in your
> test cases. Which option I should set to improve GMRES performance? Is there
> the best combination of Preconditioner and solver?
>

Solvers are highly problem dependent. There is no black box solution.

  Matt


> Thank you very much
> Jarunan
>
> --
> Jarunan Panyasantisuk
> Development Engineer
> ASCOMP GmbH, Technoparkstr. 1
> CH-8005 Zurich, Switzerland
> Phone : +41 44 445 4072
> Fax   : +41 44 445 4075
> E-mail: jarunan at ascomp.ch
> www.ascomp.ch
>



-- 
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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