dolfin team mailing list archive

["Evan Lezar" <evanlezar@xxxxxxxxx>]

On Sun, Oct 26, 2008 at 7:21 PM, Matthew Knepley <knepley@xxxxxxxxx> wrote:

> On Sun, Oct 26, 2008 at 8:13 AM, Evan Lezar <evanlezar@xxxxxxxxx> wrote:
> >
> >
> > On Sun, Oct 26, 2008 at 2:41 PM, Garth N. Wells <gnw20@xxxxxxxxx> wrote:
> >>
> >> Whether or not something is being run in parallel should be determined
> by
> >> the number of processes,
> >>
> >>  uint dolfin::MPI::num_processes()
> >>
> >> Garth
> >
> > Yes, I am aware of that, but I want to have a bit more control over the
> > parallelisation.  What I want is a number of processes each solving an
> > independent eigenvalue system (actually I am doing a sweep in frequency
> for
> > an electromagnetic problem and each frequency point has its own
> > eigensystem).
>
> There is aleady an elegant mechanism for controlling this,  namely the
> communicator.
> Every PETSc object has a communicator, thus determining how many processes
> participate. Why make up another, less powerful mechanism?
>
>   Matt
>

Fair enough.  I have to admit that I am new to PETSc and MPI programming in
general, but from what I gather from the existing PETScMatrix code is that
the only two communicators used are PETSC_COMM_WORLD and PETSC_COMM_SELF.
The selection of these is based on the value of MPI::num_processes() and as
such I have no controll over the communicator used, so in my opinion some
work is needed in this regard.

Evan

>
> > I did send an earlier mail discussing this.
> >
> > Any help with swig would be much appreciated.
> >
> > Evan
> >
> >>
> >> Evan Lezar wrote:
> >>>
> >>> Hi
> >>>
> >>> I have added a constructor to PETScMatrix to allow me to control
> whether
> >>> the matrix is to be created in parallel or not.  The declarations are
> given
> >>> below
> >>>
> >>> /// Create empty matrix
> >>> explicit PETScMatrix(Type type=default_matrix);
> >>>
> >>> /// Create an empty matrix explicitly setting the parallel flag
> >>> explicit PETScMatrix(bool is_parallel, Type type=default_matrix);
> >>>
> >>> The idea is that I use
> >>>
> >>> S = PETScMatrix(False)
> >>> If I want to create a matrix that is local.  The problem is that swig
> >>> can't differentiate between Type and bool (and uint for the
> PETScMatrix(uint
> >>> M, uint N, Type type=default_matrix); constructor).  I have seen that
> it is
> >>> possible to rename PETScMatrix(bool) to PETScMatrix_bool(bool) for
> example
> >>> so that the python call would be
> >>>
> >>> S = PETScMatrix_bool(False),
> >>>
> >>> but I can't seem to get this working.  Any suggestions?
> >>>
> >>> Thanks
> >>> Evan
> >>>
> >>>
> >>>
> ------------------------------------------------------------------------
> >>>
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> >>
> >
> >
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>
>
>
> --
> What most experimenters take for granted before they begin their
> experiments is infinitely more interesting than any results to which
> their experiments lead.
> -- Norbert Wiener
>