[petsc-users] boomerAmg scalability

[Ravi Kannan]

Dear All,

 

This is Ravi Kannan from CFD Research Corporation. Recently, we are
experimenting with the BoomerAMG preconditioner for some "stiff" CFD
problems. In that regard, all the other standard solver-preconditioner
combinations failed for the current CFD problem. The boomer is the only one
which is able to provide with "converged" solutions.

 

We noticed that the scalability of this boomer preconditioner is really
poor. For instance, even with a cell size of 2 million, we cannot scale to
even 16 partitions (in contrast, the other solver-preconditioner
combinations like the BI-CGS/BJacobi gave good enough scalability).

 

Are we missing something? Do we need to use a more latest version of boomer?

 

Thanks,

Ravi. 

 

 

 

 

 

From: petsc-dev-bounces at mcs.anl.gov [mailto:petsc-dev-bounces at mcs.anl.gov]
On Behalf Of Bobby Philip
Sent: Thursday, December 15, 2011 9:22 AM
To: For users of the development version of PETSc
Subject: Re: [petsc-dev] controlling vector values while doing matrix free
operations

 

Hmmmm..sorry guys - the entire thread got put away in a folder by my mail
reader and I just discovered all your emails :-)

 

SNESVI looks interesting but as someone pointed out I am using matrix free.
And as I understand from Barry a matrix free version of SNESVI is not
implemented. The idea of flipping the sign seems to be a poor mans approach
that might work for me though I would still need some mechanisms in SNES to
put the hooks in.

 

Bobby

 

On Dec 14, 2011, at 10:45 PM, Jed Brown wrote:





On Wed, Dec 14, 2011 at 19:40, Dmitry Karpeev <karpeev at mcs.anl.gov> wrote:

The trouble is that the constraints can get "eliminated" only when they
become active. 

 

That's not what I meant. I meant to transform the algebraic system so that
those extra variables were eliminated. The point is that we tend to put a
lot of effort into designing effective preconditioners for a standard
formulation (e.g. conservative variables), and that is partly lost of we
have this other system in which the evaluations of constitutive relations
are added explicitly.

 

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