[petsc-dev] Consider changing default installation instructions so that OS X users don't mix their MPI metaphors

[Barry Smith]

  It would be nice if the executable could somehow detect that it is being run with the wrong mpiexec command;


On Jun 5, 2011, at 9:59 AM, Aron Ahmadia wrote:

> Hi Satish,
> 
> That's reasonable.  What about the idea of adding the instructions to append $PETSC_DIR/$PETSC_ARCH/bin to your path if prefix has not been used?


    There is always the danger of giving too many instructions so all the instructions get ignored by the user. And people can misread instructions, for example I think you actually need to PREPEND the petsc bin directory not append it to the path and lots of people will get that wrong.


    I'm a fan of using the $PETSC_DIR/bin/petscmpiexec  command, but Satish is not :-)

   Barry

> 
> A
> 
> On Sun, Jun 5, 2011 at 5:32 PM, Satish Balay <balay at mcs.anl.gov> wrote:
> On Sun, 5 Jun 2011, Aron Ahmadia wrote:
> 
> > OS X and many Linux distributions now come with a system MPI.  If you
> > install by downloading MPICH and then use 'mpirun', your code will never run
> > in parallel, at best, or do something completely unexpected, at worst.
> >
> > The current default instructions are:
> >
> > export PETSC_DIR=$PWD
> > ./config/configure.py --with-cc=gcc --with-fc=gfortran
> > --download-f-blas-lapack=1 --download-mpich=1
> > make all test
> >
> > I think OS X-specific instructions that don't install MPICH or that
> > explicitly suggest appending $PETSC_DIR/$PETSC_ARCH/bin to your path when
> > running parallel jobs after installing mpich will help prevent users from
> > falling into this trap.
> 
> The above are generic instructions which work everywere. There are
> more specific examples further down - which one can check.
> 
> And OSX has broken MPI to start with - and even if we pander to that -
> most users will have issues. The best thing an OSX user can do is
> delete those files.  [yeah - one has to manually delete them - one
> can't uninstall them]
> 
> Satish
>