PETSc lib performance tuning

[Berend van Wachem]

Hi Razi,

I have tested both atlas and other blas/lapack and found small effects 
on linux.

For using ATLAS with petsc, you configure ATLAS, build it, and then 
specify when you configure petsc
--with-blas-lapack-dir=
where your ATLAS libs are. In my case, I use
--with-blas-lapack-dir=/usr/local/ATLAS/Linux_X86_64/

Good luck,
Berend.

> 
> I have a couple questions about the PETSc performance:
> 
> Does having ATLAS ( math-atlas.sourceforge.net ) help ? If so how do I
> hook it to PETSc ?
> 
> How do I best customize the compiler flags? Should I edit the
> variables directly in petscconf, or can I do it with configure ?
> 
> 
> Thanks,
> 
> Razi
>