[Mpi-22] Another MPI-2.2 attribute ambiguity?

[Jeff Squyres]

On May 19, 2009, at 8:55 PM, Jeff Squyres (jsquyres) wrote:

> So then you're in favor of #1 from my original post, right?
>
>      http://lists.mpi-forum.org/mpi-22/2009/05/0407.php
>

To be even more clear:

- Open MPI's upcoming v1.3.3 currently does #1
- Platform (Scali) MPI does #1
- HP MPI does #2
- I *think* MPICH2 is doing #1 (Bill's text can be interpreted 2 ways,  
but we already discussed that it's not valid to keep the address of  
the value passed through MPI_*_CREATE_KEYVAL)
- Alexander said that Intel MPI does the same thing as Bill's original  
reply, but I'm not sure what that means (because Bill's original reply  
was about C)

I don't know what IBM MPI, NEC MPI, or others do (I assume MS MPI and  
MVAPICH do the same thing as MPICH2).

> On May 19, 2009, at 4:39 PM, William Gropp wrote:
>
> > Silly me, I missed that.
> >
> > In Fortran (particularly thinking in terms of Fortran 77, since that
> > was the original design), the Fortran callback should be able to do
> > things like increment the "extra data" - i.e., if the extra data  
> is a
> > counter, the Fortran callback should be able to increment it.  Since
> > Fortran 77 has no pointers (and pointers in Fortran 90 aren't the  
> same
> > as addresses), having an address is worthless in a Fortran 77
> > program.  So if the MPI implementation stores the address of the  
> extra
> > data and passes that to the call back (by value, so Fortran sees the
> > address of the extra data), users should get what they expect in
> > Fortran.
> >
> > Bill
> >
> > On May 19, 2009, at 12:22 PM, Iain Bason wrote:
> >
> > >
> > > On May 19, 2009, at 1:16 PM, William Gropp wrote:
> > >
> > >> MPICH2 passes the value of the extra_state that was saved in the
> > >> internal storage to the callback routine, which is case 2 (the  
> copy
> > >> is implicit as the value is passed to the routine and C semantics
> > >> ensures that the value isn't changed).
> > >
> > > But this is the Fortran interface, not the C interface.
> > >
> > > Iain
> > >
> >
> > William Gropp
> > Deputy Director for Research
> > Institute for Advanced Computing Applications and Technologies
> > Paul and Cynthia Saylor Professor of Computer Science
> > University of Illinois Urbana-Champaign
> >
> >
> >
> >
> > _______________________________________________
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> > mpi-22_at_[hidden]
> > http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-22
> >
>
>
> --
> Jeff Squyres
> Cisco Systems
>
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-- 
Jeff Squyres
Cisco Systems