Re: [Gfs-devel] GfsOutputSpectra in parallel

[Stephane P. <s.p...@gm...>]

Hi Daniel,

> I am not sure if this is compulsory, but I had to use the very last
> version of the fftw (FFTW 3.3.1-beta1) to get it working in parallel.

Do you mean you could not use the default Debian package for fftw?

I guess not since on my system it does not include /usr/include/fftw3-mpi.h.

In this case we have two options for making this as portable as possible:
include a check in configure for fttw3-mpi.h and in the case this
check fails either:

- disable compilation of the fft module if it's not there
- or check for fftw3.h and allow only the serial version

the second option would be better of course but his implies adding #if
in your code to separate the serial from the parallel. Could you
please do this i.e.

#if HAS_FFTW3_MPI_H
...
#else /* does not have fftw3_mpi.h */
...
#endif  /* does not have fftw3_mpi.h */

then check that it can indeed build the serial or the parallel
versions and I will add the checks in configure for you.

* Please add the comments above (/* does not ... */) when you use
#ifdef HAVE_MPI in your code.

* you don't need #ifdef HAVE_MPI when you use gfs_all_reduce(), as
this macro will evaluate to nothing in serial.

> To allow for fft in parallel, I compiled using
>
> ./configure --prefix=$HOME --enable-mpi  --enable-shared CFLAGS="-fPIC"
> make && make install

You mean you compiled fttw with this? (or gerris?)

Otherwise:

- please wrap lines which are more than 100 characters wide.
- please do not replace correct indentation with crappy indentation
and then record the changes..

Please push the patch implementing these changes and we will carry on.

cheers

Stephane