On Mon, Jan 28, 2008 at 10:55:17AM -0600, Rajeev Thakur wrote:

MPI_Aint is also used for extent of a datatype and size of a window, which one may want to communicate.

One does want to communicate those things. Having an MPI_AINT would be the easiest solution, but not the cleanest or most correct... If new types were introduced, the interfaces should be changed correspondingly (eg. MPI_Count for count arguments), and that would be a big change... I don't want to push the point, though. Jesper

Rajeev

...

-----Original Message----- From: mpi-22-bounces_at_[hidden] [mailto:mpi-22-bounces_at_[hidden]] On Behalf Of Jesper Larsson Traeff Sent: Monday, January 28, 2008 7:48 AM To: Discussion of MPI Standard version 2.2 Subject: Re: [mpi-22] FW: [mpi-21] Proposal: MPI_OFFSET built-in type

On Thu, Jan 24, 2008 at 11:18:52AM -0600, Rajeev Thakur wrote:

...

A similar one is needed for MPI_Aint.

yes, it is needed... but maybe it was really not intended in MPI-1 that addresses be sent around, and therefore there was no MPI_AINT?

A cleaner (overly puristic?) solution would be to introduce more types with MPI types only for those really intended to be communicable, e.g. MPI_COUNT (MPI type for new MPI_Count type), MPI_OFFSET (for MPI_Offset), ... Unfortunately, introducing new types would/could have large consequences for the interface...

Related concerns for MPI-3.0 discussion: can MPI_Op's be sent (useful when writing MPI correctness checking software)? can MPI_Datatypes be sent (currently not - but would be very useful in combination with more functionality for manipulating datatypes)?

Jesper

...

Rajeev

...

-----Original Message----- From: mpi-22-bounces_at_[hidden] [mailto:mpi-22-bounces_at_[hidden]] On Behalf Of Richard Graham Sent: Thursday, January 24, 2008 11:09 AM To: mpi-22_at_[hidden] Subject: [mpi-22] FW: [mpi-21] Proposal: MPI_OFFSET built-in type

Moving this to the appropriate list.

Rich

------ Forwarded Message From: Robert Latham <robl_at_[hidden]> Reply-To: "Mailing list for discussion of MPI 2.1" <mpi-21_at_[hidden]> Date: Thu, 24 Jan 2008 10:41:52 -0600 To: <mpi-21_at_[hidden]> Subject: [mpi-21] Proposal: MPI_OFFSET built-in type

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 _______________________________________________ mpi-21 mailing list mpi-21_at_[hidden] http://lists.cs.uiuc.edu/mailman/listinfo/mpi-21

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