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Subject: Re: [OMPI users] mpi-io, fortran, going crazy... (ADENDA)
From: Ricardo Reis (rreis_at_[hidden])
Date: 2010-11-17 10:24:44


On Wed, 17 Nov 2010, Gus Correa wrote:

> For what is worth, the MPI addresses (a.k.a. pointers)
> in the Fortran bindings are integers, of standard size 4 bytes, IIRR.
> Take a look at mpif.h, mpi.h and their cousins to make sure.
> Unlike the Fortran FFTW "plans", you don't declare MPI addresses as big
> as you want, MPI chooses their size when it is built, right?
> As Pascal pointed out, 4-byte integers would flip sign at around 2GB,
> and even unsigned integers won't go beyond 4GB.
> Would this be part of the problem?

yes, I think is the most probable explanation. I've solved it by using
several processes to write the file (after all I just didn't want to
program a bunch of checkups required for spanning several processes for
such a simple thing...)

> I guess all the OpenMPI pros and developers are busy now
> in Bourbon Street, New Orleans, I mean, at Supercomputer 2010.
> Hard to catch their attention right now,
> but eventually somebody will clarify this.

oh, just a small grain of sand... doesn't seems worth to stop the full
machine for it...

:)

many thanks all

  Ricardo Reis

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