Open MPI logo

Open MPI User's Mailing List Archives

  |   Home   |   Support   |   FAQ   |   all Open MPI User's mailing list

Subject: Re: [OMPI users] MPI_File_Read_all and large file
From: Gus Correa (gus_at_[hidden])
Date: 2011-03-02 15:15:24


Ricardo Reis wrote:
> On Wed, 2 Mar 2011, 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?
>
> the file size per process must be lower than 4Gb
>
> There was a discussion a short time ago about this...
>
> best,
>
> Ricardo Reis
>
> 'Non Serviam'
>
> PhD candidate @ Lasef
> Computational Fluid Dynamics, High Performance Computing, Turbulence
> http://www.lasef.ist.utl.pt
>
> Cultural Instigator @ Rádio Zero
> http://www.radiozero.pt
>
> http://www.flickr.com/photos/rreis/
>
> contacts: gtalk: kyriusan_at_[hidden] skype: kyriusan
>
>

Hello Gabrielle

This thread may help:
http://www.open-mpi.org/community/lists/users/2010/11/14792.php

As Ricardo and Massimo pointed out,
the issue may be the 2GB limitation of (MPI) integers.
There is a workaround suggested on one of the thread's messages,
whereby you use MPI types to reduce the count number
in the message buffer.

I hope this helps,
Gus Correa