[mpi3-coll] Ticket 170, comment 9, both items

Torsten Hoefler htor at illinois.edu
Sun Jul 15 21:06:02 CDT 2012


Sure, done, see comment #12.

Thanks,
  Torsten

On Mon, Jul 16, 2012 at 12:31:55AM +0200, Rolf Rabenseifner wrote:
> Torsten,
> 
> please comment on ticket 170 why the sentence
> 
>  The routine is called by all group members using 
>  the same arguments for count, datatype, op and comm. 
> 
> should be wrong for MPI_SCAN and MPI_EXSCAN
> while this sentence is true
> for MPI_REDUCE and MPI_ALLREDUCE.
> 
> Without details, I would expect that this ticket 170 item
> is absolutely correct and should be done as a ticket 0
> change to clarify which rules are valid for the scan routines.
> All other reductions are clear about this.
> 
> I do not expect that you want to allow that one
> process uses MPI_FLOAT, another MPI_DOUBLE and both use MPI_SUM.
> I'm not sure wether current text does not allow this.
> Therefore clarifying wording is needed.
> 
> I would like to see the arguments and proposals in the comments to #170,
> rather than only discussion at the meeting.
> 
> Best regards
> Rolf
> 
> 
> ----- Original Message -----
> > From: "Torsten Hoefler" <htor at illinois.edu>
> > To: "Rolf Rabenseifner" <rabenseifner at hlrs.de>
> > Cc: "George Bosilca" <bosilca at eecs.utk.edu>
> > Sent: Sunday, July 15, 2012 11:24:35 PM
> > Subject: Re: Ticket 170, comment 9, both items
> > Rolf,
> > 
> > This is in no way a ticket 0, it changes semantics and I know of a
> > code
> > that will break if we change this. I would at least like to see a
> > discussion in the Forum.
> > 
> > Thanks,
> > Torsten
> > 
> > On Sat, Jul 14, 2012 at 12:14:04PM +0200, Rolf Rabenseifner wrote:
> > > Torsten and George,
> > >
> > > please commit attached coll.tex and inquiry.tex as soon as possible
> > > with
> > > (Torsten, please after the coll.tex in my previous Ticket 166 mail)
> > >
> > > Torsten:
> > >   svn ci coll.tex 'Ticket 170, Item 1 - ticket-0-change marked with
> > >   0.170'
> > >
> > > George:
> > >   svn ci inquiry.tex 'Ticket 170, Item 2 - ticket-0-change marked
> > >   with 0.170'
> > >
> > > Torsten, the added sentence is the same as for MPI_REDUCE (but
> > > without root).
> > > It is not needed in MPI_ALLREDUCE due to the very strong MPI-2.2
> > > p175:42-43.
> > > But in MPI_SCAN and EXSCAN it was missing and is now added.
> > > It is ticket-0 because it does not hurt any implementation or
> > > application
> > > and it is needed because it is undefined in MPI-2.2.
> > >
> > > George, your change is done already partially a few lines above.
> > > Also ticket-0.
> > >
> > > (I currently try to fix some overseen errors known for years.
> > > Ticket 170 is one of these error lists.)
> > >
> > > Best regards
> > > Rolf
> > >
> > >
> > > --
> > > 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: Allmandring 30)
> > 
> > 
> > 
> > --
> > ### qreharg rug ebs fv crryF ------------- http://www.unixer.de/ -----
> > Linux is like a wigwam: no Windows, no Gates, Apache inside.
> 
> -- 
> 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: Allmandring 30)
> 

-- 
### qreharg rug ebs fv crryF ------------- http://www.unixer.de/ -----
Torsten Hoefler         | Performance Modeling and Simulation Lead
Blue Waters Directorate | University of Illinois (UIUC)
1205 W Clark Street     | Urbana, IL, 61801
NCSA Building           | +01 (217) 244-7736



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