[mpiwg-rma] Bugs in RMA in current MPI standard - Re: Summary of MPI RMA WG meeting on Sept 21, 2018

[Rolf Rabenseifner]

> +1 on removing that text.  The intent was to allow Win_create too, which we
> somehow missed.
The original MPI-2 intent was, to allow only memories that were allocated by 
an MPI library routine and ***not*** just handed over by the user (as with MPI_WIN_CREATE).
This means, MPI_WIN_CREATE was originally never intented.

In MPI-2, it was therefore only MPI_ALLOC_MEM.
I do not understand, why MPI_WIN_ATTACH was added to the list.
And I expect that MPI_WIN_ALLOCATE_SHARED was overseen.
But as Jeff said, with MPI_WIN_ATTACH in the list,
this restriction does not make sense anymore.

Is there a ticket resolving this Problem in MPI-4.0
(Deadline seems to be today (or Monday noon?).

Best regards
Rolf

----- Original Message -----
> From: "Pavan Balaji" <balaji at anl.gov>
> To: "MPI WG Remote Memory Access working group" <mpiwg-rma at lists.mpi-forum.org>
> Cc: "Pavan Balaji" <balaji at anl.gov>, "Rolf Rabenseifner" <rabenseifner at hlrs.de>, "Jeff Hammond" <jeff.science at gmail.com>
> Sent: Wednesday, September 26, 2018 6:16:25 PM
> Subject: Re: [mpiwg-rma] Bugs in RMA in current MPI standard - Re: Summary of MPI RMA WG meeting on Sept 21, 2018

>> On Sep 25, 2018, at 9:38 PM, Jeff Hammond via mpiwg-rma
>> <mpiwg-rma at lists.mpi-forum.org> wrote:
>>     Implementors may restrict the use of RMA communication that
>>     is synchronized by lock calls to windows in memory allocated
>>     by MPI_ALLOC_MEM (Section 8.2), MPI_WIN_ALLOCATE (Section 11.2.2),
>>       MPI_WIN_ALLOCATE_SHARED (Section 11.2.3),
>>     or attached with MPI_WIN_ATTACH (Section 11.2.4).
>>     Locks can be used portably only in such memory.
>> 
>> 
>> 
>> I am not certain that this change is consistent with the original intent, but we
>> should just remove this text, because it does not make sense anymore.  If
>> MPI_Win_attach is sufficient to allow locks, then MPI_Win_create should be
>> there, because one can implement MPI_Win_create in terms of
>> MPI_Win_create_dynamic+MPI_Win_attach.
> 
> +1 on removing that text.  The intent was to allow Win_create too, which we
> somehow missed.
> 
>   -- Pavan

-- 
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 .
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