[petsc-dev] Sequential external packages and MPI

[Balay, Satish]

On Thu, 22 Aug 2019, Pierre Jolivet via petsc-dev wrote:

> Hello,
> PETSc is linking “sequential” libraries with MPI libraries.
> $ otool -L libmetis.dylib
> 	/usr/local/opt/mpich/lib/libmpi.12.dylib (compatibility version 14.0.0, current version 14.7.0)
> $ otool -L libfftw3.dylib
> 	/usr/local/opt/mpich/lib/libmpi.12.dylib (compatibility version 14.0.0, current version 14.7.0)

this will occur if one uses mpi compilers to build PETSc.

> Is there anyway to avoid this, by using a “sequential” compiler and/or linker?

Yes - you can build these (sequential) packages/petsc with --with-mpi=0 [and without mpi compilers]

> I’m asking because we use PETSc libraries to compile both parallel and sequential wrappers.
> Our Metis wrapper is marked as a sequential one, but since you are linking libmetis with MPI, this is problematic for some configurations.

Not sure what What mean by 'wrappers' here - esp 'Metis wrapper'. Its
just a library.

If you are using petsc build tools to install these packages for a
different use [other than the petsc usage specified by configure] -
use different petsc builds as indicated above for different packages -
as needed.

BTW: Current petsc configure/builder builds only parallel fftw. [it does not support building sequential fftw. But I guess this could be added]

Satish