[petsc-dev] testexamples using too many processes

[Satish Balay]

On Mon, 23 Mar 2015, Lisandro Dalcin wrote:

> On 23 March 2015 at 18:27, Satish Balay <balay at mcs.anl.gov> wrote:
> > nemesis has this performance degradation issue [when oversubscribing
> > cpu-cores] - so --download-mpich defaults using
> > -download-mpich-device=ch3:sock [this mode doesn't not have
> > performance degradation]
> >
> 
> Well, the thing is I always use MPI from my system package manager
> (yum or brew) and they are configured with nemesis.

yup - and thats a problem.

http://trac.mpich.org/projects/mpich/ticket/79

I don't know if openmpi also has this issue or not. So I use a
prebuilt mpich [wth ch3:sock] as my default MPI on my laptop.

What you want is to tell PETSc to not run tests that require more than - say 8 nodes - but
this feature is missing..


Satish