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Subject: Re: [OMPI users] MPI_File_Read_all and large file
From: Massimo Cafaro (massimo.cafaro_at_[hidden])
Date: 2011-03-02 12:21:51


Hi Gabriele,

MPI_File_read_all() fails because you are probably trying to read more bytes than allowed by an int. See the function's signature:

int MPI_File_read_all(MPI_File fh, void *buf, int count, MPI_Datatype datatype, MPI_Status *status)
                      

the count parameter is an int, so its maximum value may be 2147483647.
Trying to read more you will certainly get an error. So, this allows you to read about 2 GB.

With kind regards,
Massimo Cafaro

On Mar 2, 2011, at 6:02 PM, Gabriele Fatigati wrote:

>
> Dear OpenMPI users and developers,
>
> i'm using OpenMPI 1.4.3.
>
> My question is about MPI_FIle_Real_all routine and files larger than 4 GB. Is this routine able to manage this case?
>
> Using the routine with 6 GB file the routine fails, retrieving an allocation error. Investigating more in depth with Totalview, the problem appears in a line 188 of ompi/mca/io/romio/romio/adio/ad_nfs/ad_nfs_read.c:
>
> MPI_Type_size(fd->filetype, &filetype_size);
>
> here there is an explicit cast to int that can causes the problem.
>
> Someone can help me?
>
> Thanks in forward.
>
>
>
> --
> Ing. Gabriele Fatigati
>
> Parallel programmer
>
> CINECA Systems & Tecnologies Department
>
> Supercomputing Group
>
> Via Magnanelli 6/3, Casalecchio di Reno (BO) Italy
>
> www.cineca.it Tel: +39 051 6171722
>
> g.fatigati [AT] cineca.it
> _______________________________________________
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-

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 Massimo Cafaro, Ph.D. Additional affiliations:
 Assistant Professor Euro-Mediterranean Centre for Climate Change
 Dept. of Engineering for Innovation SPACI Consortium
 University of Salento, Lecce, Italy E-mail massimo.cafaro_at_[hidden]
 Via per Monteroni massimo.cafaro_at_[hidden]
 73100 Lecce, Italy cafaro_at_[hidden]
 Voice/Fax +39 0832 297371 cafaro_at_[hidden]
 Web http://sara.unisalento.it/~cafaro
       

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