[petsc-dev] PETSc MG Solvers vs agmg

[Mark F. Adams]

For structure grids you can use geometric MG which is very good.

Mark

On May 2, 2012, at 12:44 AM, Dave Nystrom wrote:

> Barry Smith writes:
>> On May 1, 2012, at 7:22 PM, Dave Nystrom wrote:
>>> 
>>>>> 2.  Is anyone on this list sufficiently familiar with agmg and the other
>>>>> PETSc mg solvers to know how to configure the PETSc mg solvers to work more
>>>>> like agmg?  It seems that agmg gives better performance than the PETSc mg
>>>>> solvers but I also have issues with agmg including fragility.
>>>> 
>>>> Please send a link for information on agmg; I've never heard of that.
>>> 
>>> http://homepages.ulb.ac.be/~ynotay/AGMG
>> 
>> Ok, this general approach is what the Trilinos ML solver users (which is a
>> fairly good) and what Mark Adams is adding to PETSc in PCGAMG.
> 
> Thanks for this info.
> 
>> You can start by ./configure PETSc with --download-ml and then run the
>> program with -pc_type mg
> 
> I assume you mean "-pc_type ml".  I have actually configured and run
> petsc-dev with gamg, ml and hypre-boomeramg.  I have just used the default
> parameters because I am not sure which of the parameters would be most useful
> to try and tune.  It has seemed that ML has given the best results so far but
> those results in terms of run time performance are not as good as agmg.
> 
> I'd like to somehow get educated on how to intelligently tune the adjustable
> parameters on these various MG packages and ML seems a good place to start.
> But I'm not quite sure how to get started since there are enough adjustable
> parameters that exploring parameter space could be challenge.
> 
> Perhaps there is some good documentation on this.  I guess I should google
> "Trilinos ML documentation" and see what I find.  My solves are on a 2d
> structured mesh and I have 8 of them of various flavors.
> 
>> You can run with -ksp_view to see the number of levels etc it ended up
>> with and
>> http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/PC/PCML.html
>> for some options.
> 
> Thanks again.
> 
> Dave
> 
>> Barry
>> 
>>> 
>>>> Barry
>>>> 
>>>>> 
>>>>> Thanks,
>>>>> 
>>>>> Dave
>> 
>