[MPIWG Fortran] MPI-3 ticket 349: Fortran question

Jim Dinan james.dinan at gmail.com
Thu Dec 12 10:51:30 CST 2013 

Hi Rolf,

Thanks for the corrections -- I apologize, what I had sent was a very rough
draft of the proposal.  I applied your changes to the proposal, cleaned
some things up, and added the datatypes examples corrections.  Could you
take another look when you get a chance?

In terms of proposal logistics, I would like to let MPI_Aint add and diff
tickets progress independently.  I agree that they need to be together, and
I think we can rely on the chapter committee to handle that if add/diff end
up split between two versions of the standard.  MPI_Aint_diff should be
ready for a reading at the next meeting and MPI_Aint_add will be ready for
a first vote.  Given the discussion about MPI 3.x/4.0 timeline yesterday, I
think the risk of these not being in the same release of the spec is very
low.  Since the Forum has already done all of the work required to move
MPI_Aint_add to a vote, I would prefer not to rewind this process by
merging it with the diff ticket.

 ~Jim.


On Thu, Dec 12, 2013 at 9:14 AM, Rolf Rabenseifner <rabenseifner at hlrs.de>wrote:

> Jim and all,
>
> MPI_Get_address((char *) addr1 - (char *) addr2, &result)
>
> This is really wrong, because (char *) addr1 - (char *) addr2
> is not an address and cannot be used as input to MPI_Get_address.
>
> (char *) addr1 - (char *) addr2 is a displacement.
>
> Both tickets 349 and 404 need to be together, because they
> are based on a clear distinguishing between
>  - Location in memory (input of MPI_GET_ADDRESS), e.g. x, y
>  - absolute addresses (output of MPI_GET_ADDRESS), e.g., addr_x, addr_y
>  - relative displacements (diff of two absolute addresses), e.g. dist_xy
>
> Your new statement is that calculations like
>   dist_xy = addr_y - addr_x
>   addr_y = addr_x + dist_xy
> need to be done by subroutine calls or functions,
> because absolute addresses are stored in MPI_Aint variables
> through some (unknown/strange) mapping,
> wheras relative displacements are normal unsigned integers
> that can be used for normal arithmetic.
>
> The one ticket must show this clearly and must be integrated into section
> 4.1.5
>
> Best regards
> Rolf
>
>
> ----- Original Message -----
> > From: "Jim Dinan" <james.dinan at gmail.com>
> > To: "Rolf Rabenseifner" <rabenseifner at hlrs.de>
> > Cc: "MPI-WG Fortran working group" <mpiwg-fortran at lists.mpi-forum.org>,
> "longb" <longb at cray.com>, "Jim Dinan"
> > <dinan at mcs.anl.gov>
> > Sent: Thursday, December 12, 2013 3:20:41 PM
> > Subject: Re: [MPIWG Fortran] MPI-3 ticket 349: Fortran question
> >
> >
> > Hi Rolf,
> >
> >
> > Thank you very much for the feedback!  Sorry if I forgot to respond;
> > the comments definitely were not ignored.  We discussed the Aint
> > difference calculation in the working group and decided to create an
> > additional ticket for MPI_Aint_disp.  We did not see a clean way to
> > handle this in MPI_Aint_add, because both arguments need to be
> > handled as unsigned in the arithmetic.
> >
> >
> > https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/404
> >
> >
> >
> > I have a list of fixes the to the datatypes examples that I'll post
> > to the ticket soon.
> >
> >
> > Jeff Squyres is also helping us move the MPI_Aint arithmetic routines
> > to functions in the Fortran bindings.  Should be done today.
> >
> >
> > Were there any other concerns that we missed?
> >
> >
> > Thanks,
> >  ~Jim.
> >
> >
> >
> > On Thu, Dec 12, 2013 at 1:42 AM, Rolf Rabenseifner <
> > rabenseifner at hlrs.de > wrote:
> >
> >
> > Jeff and Bill,
> >
> > < https://svn.mpi-forum.org/trac/mpi-forum-web/ticket/349#comment:22
> > >
> > was ignored.
> > The answer seems to be yes and the clear implication is that
> > we need also a routine to calculate disp := addr2-addr1
> >
> > About the Fortran Interfaces:
> > We should keep the old style without INTENT, because for the
> > old-style
> > the implementor has the freedom to add INTENT as he/she wants
> > and it is still compliant with the outcome of the definition.
> >
> > I do not see, why we have a function in C and a subroutine
> > in Fortran.
> > Like MPI_Wtime, in all three languages (C, new and old Fortran),
> > we should do the same.
> >
> > Best regards
> > Rolf
> >
> > ----- Original Message -----
> > > From: "Jeff Squyres (jsquyres)" < jsquyres at cisco.com >
> > > To: "< longb at cray.com >" < longb at cray.com >, "MPI-WG Fortran
> > > working group" < mpiwg-fortran at lists.mpi-forum.org >
> > > Sent: Thursday, December 12, 2013 12:17:40 AM
> > > Subject: Re: [MPIWG Fortran] MPI-3 ticket 349: Fortran question
> > >
> > > Sounds good to me.
> > >
> > > Rolf -- is there any MPI reason we would not want to do this?
> > >
> > >
> > > On Dec 11, 2013, at 4:41 PM, Bill Long < longb at cray.com > wrote:
> > >
> > > >
> > > >
> > > > On 12/11/13 11:27 AM, Jeff Squyres (jsquyres) wrote:
> > > >> This ticket got a formal reading today at the Forum:
> > > >>
> > > >>     http://svn.mpi-forum.org/trac/mpi-forum-web/ticket/349
> > > >>     (as of this writing, there's still a BIND(C) in there, but
> > > >> it
> > > >>     will be removed shortly)
> > > >>
> > > >> The function is basically intended to perform a mathematical
> > > >> operation.  As such, I think that the 2 Fortran bindings should
> > > >> be FUNCTIONs, not SUBROUTINEs (a la MPI_WTICK/MPI_WTIME).
> > > >>
> > > >> Do you agree?  If so, the ticket author (Jim Dinan) is amenable
> > > >> to
> > > >> changing the Fortran bindings to the following (and I'm assuming
> > > >> I have the syntax below correct, but feel free to correct me if
> > > >> they're wrong):
> > > >>
> > > >
> > > > Certainly it makes more sense for these to be functions in
> > > > Fortran.
> > > > Particularly if the programmer prefers supply an interface and
> > > > call the C form directly.  If the C and Fortran versions are both
> > > > functions, there is no change in the source code where the
> > > > function is used.
> > > >
> > > >> -----
> > > >> INTEGER(KIND=MPI_ADDRESS_KIND) MPI_Aint_add(base, disp)
> > > >>     INTEGER(KIND=MPI_ADDRESS_KIND), INTENT(IN) ::  base, disp
> > > >>
> > > >> INTEGER(KIND=MPI_ADDRESS_KIND) MPI_AINT_ADD(BASE, DISP)
> > > >>     INTEGER(KIND=MPI_ADDRESS_KIND) BASE, DISP
> > > >
> > > > It is certainly an oddity that the spec has two forms like this.
> > > >  Any version of the Fortran standard that supports KIND= in
> > > > INTEGER also supports lower case names and INTENT() attributes.
> > > >   Maybe there could be some clean up of this in a future
> > > > revision.
> > > >
> > > > Cheers,
> > > > Bill
> > > >
> > > >
> > > >
> > > >> -----
> > > >>
> > > >
> > > > --
> > > > Bill Long
> > > > longb at cray.com
> > > > Fortran Technical Support    &                 voice:
> > > > 651-605-9024
> > > > Bioinformatics Software Development            fax:
> > > > 651-605-9142
> > > > Cray Inc./Cray Plaza, Suite 210/380 Jackson St./St. Paul, MN
> > > > 55101
> > > >
> > > >
> > > > _______________________________________________
> > > > mpiwg-fortran mailing list
> > > > mpiwg-fortran at lists.mpi-forum.org
> > > > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran
> > >
> > >
> > > --
> > > Jeff Squyres
> > > jsquyres at cisco.com
> > > For corporate legal information go to:
> > > http://www.cisco.com/web/about/doing_business/legal/cri/
> > >
> > > _______________________________________________
> > > mpiwg-fortran mailing list
> > > mpiwg-fortran at lists.mpi-forum.org
> > > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-fortran
> > >
> >
> > --
> > Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner at hlrs.de
> > 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: Room 1.307)
> >
> >
>
> --
> Dr. Rolf Rabenseifner . . . . . . . . . .. email rabenseifner at hlrs.de
> 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: Room 1.307)
>
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