PETSc version 3.0.0-p2

Lisandro Dalcin dalcinl at
Thu Jan 29 14:01:49 CST 2009

Sorry for the late response.

In 3.0.0, some things have changed in ASM. Now ASM try to make a
"smart" subdomain partitioning, they are likely to improve things in
the case of unstructured grid problems or many subdomanins per
processor. However, if your problem is on a structured grid, and you
are using 2 processors, and let say 4 subdomains (i.e., 2
subdoms/proc), then in that particular case the new "smart"
partitioning could be a bit worse than the one obtained with the old
code. But I would not expect a dramatic difference in the GMRES
iteration counts...

The differences will only show-up if you built PETSc with ParMETIS and
you are using more than 1 subdomain per processor.  Is this your case?

On Sun, Jan 25, 2009 at 3:35 PM, Billy Araújo <billy at> wrote:
> I compiled my code using the new version of PETSc but the convergence of the
> GMRES has suffered greatly, specially in parallel. I am using GMRES with ASM
> preconditioner.
> Has there been any change?
> Billy.

Lisandro Dalcín
Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
PTLC - Güemes 3450, (3000) Santa Fe, Argentina
Tel/Fax: +54-(0)342-451.1594

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