MPI-2 general question

[weymouth]

I'm sorry if this has been covered elsewhere, but I can't seem to find
any information on using MPI-2 commands to generate human readable
output files.

Actually, the files are not going to be read by humans (except for the
occasional sanity check) but they need to be readable for various
visualization and post-processing programs - all of which are serial
and have specific formatting requirements.

Is MPI-2 the correct choice for this kind of thing? If so, what kind
of commands do I need to write ASCII headers? If I write a header
using serial I/O, how to adjust the view for the parrallel I/O to
follow? Can I write the whole file in ASCII? Should I just give this
junk up and write a second program to stitch a set of files together?

[Heiko Bauke]

Hi,

On Fri, 9 Apr 2010 10:35:57 -0700 (PDT)

Post by weymouth
Actually, the files are not going to be read by humans (except for the
occasional sanity check) but they need to be readable for various
visualization and post-processing programs - all of which are serial
and have specific formatting requirements.
Is MPI-2 the correct choice for this kind of thing? If so, what kind
of commands do I need to write ASCII headers? If I write a header
using serial I/O, how to adjust the view for the parrallel I/O to
follow? Can I write the whole file in ASCII? Should I just give this
junk up and write a second program to stitch a set of files together?

binary representation is the canonical way to write data using MPI I/O.
So writing a whole file in ASCII mode is virtually impossible. However,
writing an ASCII header by a single process should not be a problem. Use
MPI_File_set_view and an appropriate displacement. See
http://www.mpi-forum.org/docs/mpi22-report/node261.htm and following
pages, especially http://www.mpi-forum.org/docs/mpi22-report/node274.htm


Heiko