[mpi-22] FW: [mpi-21] Proposal: MPI_OFFSET built-in type

[Jesper Larsson Traeff]

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
> > _______________________________________________
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> > mpi-21_at_[hidden]
> > http://lists.cs.uiuc.edu/mailman/listinfo/mpi-21
> > 
> > ------ End of Forwarded Message
> > 
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> > 
> 
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