[mpi-22] Fwd: Proposal: MPI_OFFSET built-in type

[Rolf Rabenseifner]

There is already a bullet on that topic, see

MPI_AINT, MPI_OFFSET 
  Is there an MPI datatype that can be used to send and receive 
  these values? This needed by applications working with MPI 
  windows and files. 
in section Clarifications (10th item there) on 
http://www.cs.uiuc.edu/homes/wgropp/projects/parallel/MPI/mpi-errata/

Bill Gropp has proposed to put this topic on the agenda of MPI 2.2.
I agree and I'm forwarding your mail therefore to the MPI 2.2 mailing list.

On Thu, 24 Jan 2008 10:41:52 -0600
 robl_at_[hidden] (Robert Latham) wrote:
>I hope this is less contentious than adding 'const' keywords...
>
>
>I would like to propose a new built-in type MPI_OFFSET, defined to be
>a type corresponding to INTEGER(KIND=MPI_OFFSET_KIND) or MPI_Offset
>
>This is a minor addition to the standard, which would have no impact
>on existing code while serving to simplify code which exchanges file
>offsets among processes.
>
>There is a workaround in the standard: a user can define a type from
>MPI_BYTE:
>
> MPI_Type_contiguous(sizeof(MPI_Offset), MPI_BYTE, &offtype);
>
>However, it would clearly be more convienient to operate on built-in
>types.  
>
>MPI Datatype: MPI_OFFSET
>Corresponding C type: long long int
>Corresponding Fortran type: INTEGER(KIND=MPI_OFFSET_KIND)
>
>
>Thanks
>==rob
>
>-- 
>Rob Latham
>Mathematics and Computer Science Division    A215 0178 EA2D B059 8CDF
>Argonne National Lab, IL USA                 B29D F333 664A 4280 315B
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Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner_at_[hidden]
High Performance Computing Center (HLRS) . phone ++49(0)711/685-65530
University of Stuttgart . . . . . . . . .. fax ++49(0)711 / 685-65832
Head of Dpmt Parallel Computing . . . www.hlrs.de/people/rabenseifner
Nobelstr. 19, D-70550 Stuttgart, Germany . (Office: Allmandring 30)