[Mpi3-rma] RMA proposal 2 initial text

[Hubert Ritzdorf]

Hi Thorsten,

Thanks for the clarification. I detected that this were 2 
different documents with the same name in different directories
after my mail. Nevertheless, my remarks found the right persons.

Many thanks

Hubert

> -----Original Message-----
> From: mpi3-rma-bounces at lists.mpi-forum.org [mailto:mpi3-rma-
> bounces at lists.mpi-forum.org] On Behalf Of Torsten Hoefler
> Sent: Tuesday, November 02, 2010 8:04 PM
> To: MPI 3.0 Remote Memory Access working group
> Subject: Re: [Mpi3-rma] RMA proposal 2 initial text
> 
> Hubert,
> 
> Thanks for the review. First let me explain our methodology. There are
> two proposals (named "1" and "2"). Proposal 1, which contains all
> essential changes, is maintained by Bill and me and proposal 2, which
> contains possible extensions, is maintained by Pavan.
> 
> Both can be found on the wiki
> https://svn.mpi-forum.org/trac/mpi-forum-web/wiki/RmaWikiPage
> 
> So some of your comments refer to 1 and some to 2. Pavan forked proposal
> 2 form an earlier version of proposal 1. So I will reply to the subset
> of your comments that effects proposal 1 :-).
> 
> On Tue, Nov 02, 2010 at 01:50:44PM +0100, Hubert Ritzdorf wrote:
> > Some remarks to the actual document:
> >
> > (*) Page 23: MPI_COMPARE_AND_SWAP and
> >     What does ``bitwise identical'' mean for a portable
> >     MPI datatype such as C int which may have different
> >     sizes in heterogeneous environments.
> That is a very good comment. We had the datatype discussions before and
> I forgot to remove the bitwise. We shall talk about it at the next
> telecon.
> 
> > (*) Page 23: MPI_COMPARE_AND_SWAP and MPI_GET_ACCUMULATE
> >     Which datatypes (and alignments) are fast in hw is
> >     dependent on the target rank (and possibly window)
> >     in non-homogeneous systems. I can't see, how this
> >     can be handled by a portable program without query
> >     functions by only checking the documentation.
> Yes, I agree. The MPI_RMA_QUERY could be used to query this. We shall
> discuss this at the next telecon.
> 
> > (*) Example 11.15, Process A:
> >     I think, that there is missing a MPI_Win_membar after
> >     X = 2 before MPI_Barrier.
> >     Correspondingly, I think that MPI_Win_membar is missing after
> >     assignments to X, Y, A in Examples 11.16 and 11.17.
> That should still be correct. If process a issues a win_flush(A) which
> itself only returns after the data arrived at the destination (public
> window) and the data is only accesses through RMA calls (as it should be
> in the examples), then it should be correct. A membar should be able to
> achieve the same -- but might be less elegant.
> 
> Best,
>   Torsten
> 
> --
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> Torsten Hoefler         | Performance Modeling and Simulation Lead
> Blue Waters Directorate | University of Illinois (UIUC)
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