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

[Jesper Larsson Traeff]

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
> > > > 
> > > > ------ End of Forwarded Message
> > > > 
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