Newsgroups: comp.parallel.mpi
From: brad@rosalyn.cs.washington.edu (Bradford Chamberlain)
Subject: QUERY:terminal I/O in ROMIO, MPI-2
Organization: Computer Science & Engineering, U of Washington, Seattle
Date: Wed, 15 Jul 1998 21:38:01 GMT
Message-ID: <BRAD.98Jul15143801@rosalyn.cs.washington.edu>


Sorry if this is a repost: I noticed after the first post that my
distribution was set to local.

I was excited to read about MPICH's incorporation of ROMIO in v1.1.1
this past week, due to long-term headaches that I've experienced in
trying to do I/O in a portable way within my MPI programs.

My question is whether I/O as defined in MPI-2 and implemented in
ROMIO supports cooperative terminal I/O (e.g. C's stdin, stdout,
stderr) amongst MPI tasks.  I've begun slogging my way through the I/O
section of the MPI-2 spec, and noticed the section dealing with random
access vs. sequential files.  It gives me the impression that I ought
to be able to access the terminal in MPI_MODE_SEQUENTIAL mode, but
it's not clear to me how I would get a handle to stdout (e.g.) to
begin with -- the file open call doesn't seem rich enough to get at
stdout.

As a particular example, I have an array distributed across multiple
MPI tasks and would like them to cooperatively print out the array to
stdout so that it appears as one contiguous ordered whole.  So far
(using MPI-1) I've been unable to find a solution that works across
all platforms.  Will ROMIO and MPI-2's I/O scheme save me?

Thanks for any suggestions,
-Brad