[Mpi3-rma] MPI-3.1 consideration slides

[Hubert Ritzdorf]

NEC SX (including the Earth Simulator) memory is not cache coherent and
MPI-2 RMA is working since many years on these systems.

Hubert
________________________________________
From: mpi3-rma-bounces at lists.mpi-forum.org [mpi3-rma-bounces at lists.mpi-forum.org] on behalf of Jim Dinan [dinan at mcs.anl.gov]
Sent: Monday, December 03, 2012 4:39 PM
To: mpi3-rma at lists.mpi-forum.org
Subject: Re: [Mpi3-rma] MPI-3.1 consideration slides

On 12/2/12 7:44 AM, Jeff Hammond wrote:
>>> (1) Define semantics of shared memory windows in separate model.
>>>
>>> In Section 11.2.3 it says "MPI does not define semantics for accessing
>>> shared memory windows in the separate memory model."
>>>
>>> I would like to try to define these semantics in MPI 3.1.  Shouldn't
>>> it at least be possible to use MPI_WIN_(UN)LOCK with
>>> MPI_LOCK_EXCLUSIVE here?
>>>
>>> I believe that supporting RMA for weakly- or non- coherent memory
>>> architectures is vital for future systems.
>> I agree. We had this discussion and decided to postpone it because we
>> had other more pressing issues. Now may be the time. A discussion would
>> be good.
>
> Yes, there was no urgency.  I'm glad the standard left this issue wide
> open instead of defining something restrictive.

IMHO, defining shared memory windows in the separate model is not a
worthy use of the Forum's time.  This will be hard to get right, and
AFAIK no (reasonable) system requires it.  As we've currently left it,
if this functionality is needed, one can define the semantics as an MPI
extension.  I think this is a better option that defining a new model in
the absence of a platform that uses it.

  ~Jim.
_______________________________________________
mpi3-rma mailing list
mpi3-rma at lists.mpi-forum.org
http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi3-rma


 Click https://www.mailcontrol.com/sr/BMhj+WAEk+nGX2PQPOmvUpFBc4ZD8M8UQDU1HKsp9BM+kyw4sOr0J9g!Ah9tEzkBYIOMBNusRzyg1M3YVHc55g==  to report this email as spam.