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Subject: Re: [OMPI users] mpi-io, fortran, going crazy... (ADENDA)
From: Ricardo Reis (rreis_at_[hidden])
Date: 2010-11-17 05:10:41


On Wed, 17 Nov 2010, Pascal Deveze wrote:

> I think the limit for a write (and also for a read) is 2^31-1 (2G-1). In a C
> program, after this value, an integer becomes negative. I suppose this is
> also true in
> Fortran. The solution, is to make a loop of writes (reads) of no more than
> this value.

Is that MPI-IO specific? I remember that when using FFTW they ask for
using INTEGER(8) for the returning handle. This is used has a pointer
interface with the library and (8) will be equivalent to a 64 bit pointer
(sort of, sorry if I am not being exact).

Anyway, if I have no problems writing Big files with normal Fortran
shouldn't this behaviour be found with MPI-IO? And, more to the point, if
not, shouldn't it be documented somewhere?

Does anyone knows if this carries over to other MPI implementations (or
the answer is "download, try it and tell us?")

best,

  Ricardo Reis

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