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Subject: Re: [OMPI devel] MPI_File_get_size fails for files > 2 GB in Fortran
From: George Bosilca (bosilca_at_[hidden])
Date: 2010-12-20 14:55:19


Not really. The Fortran prototype from our man page is:

    INCLUDE ’mpif.h’
    MPI_FILE_GET_SIZE(FH, SIZE, IERROR)
    INTEGER FH, ERROR
    INTEGER(KIND=MPI_OFFSET_KIND) SIZE

So the size is of type MPI_OFSET_KIND which is INTEGER*8 (signed). There is still a mismatch between of C and the Fortran version (size_t vs. ssize_t on my platform), but let's save this for later.

  george.

On Dec 20, 2010, at 14:48 , Edgar Gabriel wrote:

> well, but the f77 interface defines that to be an integer, unless you
> want to change the fortran API, you will have to map it to an MPI_Fint
> in my opinion.
>
> Edgar
>
> On 12/20/2010 1:36 PM, George Bosilca wrote:
>> Nice catch. The sizes are MPI_Offset in C, and therefore we should not cast them as MPI_Fint. I'll take a look, but I doubt it will be before next year. Meanwhile, patches are always welcomed.
>>
>> george.
>>
>> On Dec 20, 2010, at 10:59 , William George wrote:
>>
>>>
>>> In Fortran, calls to MPI_File_get_size return a negative value
>>> when the file is larger that 2GB.
>>>
>>> I am using Open MPI 1.4.3 on an x86_64 system. This happens with OpenMPI
>>> compiled with Intel compilers or GCC, so I don't think it has
>>> anything to do with the particular compiler in use.
>>>
>>> I can fix this by removing the cast to MPI_Fint in
>>> the function mpi_file_get_size_ in ompi/mpi/f77/file_get_size_f.c.
>>>
>>> Changing:
>>> *size = (MPI_Fint) c_size;
>>>
>>> To:
>>>
>>> *size = c_size;
>>>
>>>
>>> But my guess is that this is not a proper fix.
>>>
>>> There are a few other suspicious casts to MPI_Fint in the f77
>>> directory too that probably cause similar problems:
>>>
>>> $ $ grep \(MPI_Fint\) *.c
>>> address_f.c: *address = (MPI_Fint) addr;
>>> file_get_position_f.c: *offset = (MPI_Fint) c_offset;
>>> file_get_position_shared_f.c: *offset = (MPI_Fint) c_offset;
>>> file_get_size_f.c: *size = (MPI_Fint) c_size;
>>> file_get_view_f.c: *disp = (MPI_Fint) c_disp;
>>> type_extent_f.c: *extent = (MPI_Fint)c_extent;
>>>
>>>
>>> I can also fix this problem by compiling OpenMPI with
>>> the flag -i8, but promoting all Fortran INTEGERs to 8-bytes
>>> does not seem correct either.
>>>
>>> So - is this a configuration problem, a compile problem.
>>> a source code bug, or what? Is there an MPI_FOffsetint
>>> and/or MPI_FAddressint type that should be used
>>> in these casts?
>>>
>>>
>>> Regards,
>>> --
>>> Bill
>>>
>>> William L. George
>>> National Institute of Standards and Technology
>>> ITL - Applied and Computational Mathematics Division, Stop 8911
>>> 100 Bureau Drive
>>> Gaithersburg, MD 20899-8911
>>>
>>>
>>> _______________________________________________
>>> devel mailing list
>>> devel_at_[hidden]
>>> http://www.open-mpi.org/mailman/listinfo.cgi/devel
>>
>>
>> _______________________________________________
>> devel mailing list
>> devel_at_[hidden]
>> http://www.open-mpi.org/mailman/listinfo.cgi/devel
>
> --
> Edgar Gabriel
> Assistant Professor
> Parallel Software Technologies Lab http://pstl.cs.uh.edu
> Department of Computer Science University of Houston
> Philip G. Hoffman Hall, Room 524 Houston, TX-77204, USA
> Tel: +1 (713) 743-3857 Fax: +1 (713) 743-3335
>
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