[Mpi3-rma] [EXTERNAL] Re: Disp_unit in allocate_shared should be returned by win_shared_query?

[Barrett, Brian W]

Sorry to chime in late; I've been on vacation the last week.

I'm comfortable with option #2 and agree entirely with Bill that it's too late to add an advice to users about allocation.

Brian

On Jul 26, 2012, at 7:54 PM, William Gropp wrote:

> The advice to users is not essential, and at this point, we should *only* be making essential changes.  This is a standards document, not a user manual.  I'm all for having man pages and tutorials say things like this, but we don't need it in the standard.
> 
> Bill
> 
> William Gropp
> Director, Parallel Computing Institute
> Deputy Director for Research
> Institute for Advanced Computing Applications and Technologies
> Paul and Cynthia Saylor Professor of Computer Science
> University of Illinois Urbana-Champaign
> 
> 
> 
> On Jul 26, 2012, at 4:22 PM, Rolf Rabenseifner wrote:
> 
>>> I guess we can add this advice nevertheless. I think this would also
>>> cover Rolf's comment.
>> 
>> Not really. The text is orthogonal to my request.
>> 
>>>> Advice to users. If disp_unit values differ across processes in a
>>>> shared memory window, the programmer may need to use the target's
>>>> disp_unit value in address calculations and use different load/store
>>>> operations depending on the target's disp_unit value. (End of advice
>>>> to
>>>> users.)
>> 
>> This is an advice especially for MPI_WIN_ALLOCATE_SHARED.
>> It does not fit to MPI_WIN_ALLOCATE and the use of MPI_PUT/GET
>> because in PUT/GET, the disp_unit works perfect.
>> 
>> My question was a general one at MPI_WIN_CREATE
>> to tell the users that the major intend is that all disp_unit values 
>> (related to the processes of one window handle)
>> represent the extent of one common datatype.
>> And, if one is doing different, this may cause a
>> non-scaling memory overhead.
>> 
>> Rolf 
>> 
>> ----- Original Message -----
>>> From: "Torsten Hoefler" <htor at illinois.edu>
>>> To: "MPI 3.0 Remote Memory Access working group" <mpi3-rma at lists.mpi-forum.org>
>>> Sent: Thursday, July 26, 2012 11:05:56 PM
>>> Subject: Re: [Mpi3-rma] [EXTERNAL] Re: Disp_unit in allocate_shared should be returned by win_shared_query?
>>> On Thu, Jul 26, 2012 at 11:18:05AM -0500, James Dinan wrote:
>>>> I do have a concern that different disp_units can occur unexpectedly
>>>> because of heterogeneous hardware or software -- e.g. MPMD launch
>>>> with
>>>> different executables or language incompatibility where both C and
>>>> Fortran code are involved in creating the window.
>>>> 
>>>> Rather than ruling these cases out (option #1), how about including
>>>> the
>>>> following advice to users:
>>>> 
>>>> Advice to users. If disp_unit values differ across processes in a
>>>> shared memory window, the programmer may need to use the target's
>>>> disp_unit value in address calculations and use different load/store
>>>> operations depending on the target's disp_unit value. (End of advice
>>>> to
>>>> users.)
>>>> 
>>>> If we included this, I think I would be ok with option #2.
>>> I don't object, however, we're supposed to freeze the document by
>>> today.
>>> I guess we can add this advice nevertheless. I think this would also
>>> cover Rolf's comment.
>>> 
>>>> An orthogonal observation -- it would have given us a lot more
>>>> flexibility to define MPI_Win_shared_query as:
>>>> 
>>>> int MPI_Win_shared_get_attr(MPI_Win win, int target_rank, int
>>>> win_keyval, void *attribute_val, int *flag)
>>> Of course. I still like the MPI_Func(...) idea :-).
>>> 
>>> But I agree, this would also fit the current design with attributes
>>> better. Hmm, is probably too late for such a syntactic sugar change.
>>> Any
>>> opinions?
>>> 
>>> All the Best,
>>> Torsten
>>> 
>>> --
>>> ### 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
>>> _______________________________________________
>>> mpi3-rma mailing list
>>> mpi3-rma at lists.mpi-forum.org
>>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma
>> 
>> -- 
>> 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)
>> _______________________________________________
>> mpi3-rma mailing list
>> mpi3-rma at lists.mpi-forum.org
>> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma
> 
> 
> _______________________________________________
> mpi3-rma mailing list
> mpi3-rma at lists.mpi-forum.org
> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma
> 

-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 3097 bytes
Desc: not available
URL: <http://lists.mpi-forum.org/pipermail/mpiwg-rma/attachments/20120727/183b9a17/attachment-0001.bin>