[mpiwg-rma] [Mpi-forum] 3/14: Formal Readings

Wed Feb 19 11:44:57 CST 2014

Jim,

Yes Jim, you are fully right and I updated ticket 413 according to
your corrections.
Thank you for your carefully reading and your corrections.

The reason for this ticket is very simple:
Nothing about the use of MPI_Win_sync for the use-case 
in this example is really explained by MPI-3.0.
I expect, that for MPI-4.0, the rules for RMA synchronization
for shared memory windows must be revisited.
But this would be another ticket.

Best regards
Rolf

----- Original Message -----
> From: "Jim Dinan" <james.dinan at gmail.com>
> To: "MPI WG Remote Memory Access working group" <mpiwg-rma at lists.mpi-forum.org>
> Cc: "Rolf Rabenseifner" <rabenseifner at hlrs.de>, "Jeff Squyres" <jsquyres at cisco.com>
> Sent: Monday, February 17, 2014 11:30:42 PM
> Subject: Re: [mpiwg-rma] [Mpi-forum] 3/14: Formal Readings
> 
> 
> Rolf,
> 
> 
> I think this ticket needs to be reviewed by the RMA WG before moving
> it forward.  I would suggest updating the text to incorporate the
> following changes:
> 
> 
> Example 11.13 demonstrates the proper synchronization in the unified
> memory model when a data transfer is implemented with load and store
> (instead of MPI_PUT or MPI_GET) and the synchronization between
> processes is performed using point-to-point communication. The
> synchronization between processes must be supplemented with a memory
> synchronization through calls to MPI_WIN_SYNC, which act locally as
> a processor-memory barrier.  In Fortran, reordering of the
> MPI_WIN_SYNC calls must be prevented with MPI_F_SYNC_REG operations.
> 
> The variable X is contained within a shared memory window and X
> corresponds to the same memory location at both processes. The
> MPI_WIN_SYNC operation performed by process A ensures completion of
> the load/store operations issued by process A. The MPI_WIN_SYNC
> operation performed by process B ensures that process A's updates to
> X are visible to process B.
> 
> In the example, I don't see the reason for the second set of SYNC
> operations after B's read of X.  If A updates X and B only reads it,
> the second send/recv synchronization should be sufficient.  That is,
> B has not made any updates to X that need to be made visible A, and
> B's read of X will be ordered because of the send operation.  The
> F_SYNC could still be needed to preserve this ordering.
> 
> 
>  ~Jim.
> 
> 
> 
> On Mon, Feb 17, 2014 at 12:23 PM, Jeff Hammond <
> jeff.science at gmail.com > wrote:
> 
> 
> Switching to the WG list so that everyone is involved...
> 
> I do not see adding an example as so urgent that it needs to be dealt
> with at the next meeting, given how overloaded the relevant people
> are.
> 
> Honestly, it is more likely to be read by users if the example and
> commentary on it are the subject of a blog post on Squyres' blog.  At
> the very least, that will ensure Google indexes it and thus curious
> people will find it (as much cannot be said for the MPI standard
> itself).
> 
> Jeff
> 
> 
> 
> On Mon, Feb 17, 2014 at 10:50 AM, Rolf Rabenseifner
> < rabenseifner at hlrs.de > wrote:
> > Pavan,
> > 
> > do you put also #413 on the list.
> > I believe, it's better to have it on the list
> > although it is only an example and therefore the RMA group
> > may put it on the errata without plenary.
> > Please can you do all what is needed
> > that it comes on the MPI-3.0 errata list.
> > 
> > Best regards
> > Rolf
> > 
> >> Pavan,
> >>    thank you for supporting it in the March meeting (Rajeev will
> >> not
> >>    be there).
> >>    Is there a RMA WG Meeting at the March Forum Meeting?
> >>    Will you do an MPI-3.0 errata plenary reading
> >>    or will you put it into the errata by WG dicision,
> >>    because it is only an example?
> >>    In both cases #413 should be latest tomorrow on the agenda.
> >> 
> >>    Because it is one block of text at one precise location,
> >>    the ticket format may be enough formalism, i.e., no extra pdf.
> > 
> > ----- Original Message -----
> >> From: "Jim Dinan" < james.dinan at gmail.com >
> >> To: "Main MPI Forum mailing list" < mpi-forum at lists.mpi-forum.org
> >> >
> >> Sent: Monday, February 17, 2014 4:35:51 PM
> >> Subject: [Mpi-forum] 3/14: Formal Readings
> >> 
> >> 
> >> 
> >> Hi All,
> >> 
> >> 
> >> The RMA and Hybrid working groups would like to put forward the
> >> following tickets for formal readings at the upcoming meeting:
> >> 
> >> 
> >> #380 - Endpoints proposal
> >> 
> >> 
> >> https://svn.mpi-forum.org/trac/mpi-forum-web/attachment/ticket/380/mpi-report.pdf
> >> 
> >> 
> >> Read by: Pavan Balaji
> >> 
> >> 
> >> #349, #402, #404 - Address arithmetic proposal
> >> 
> >> 
> >> 
> >> https://svn.mpi-forum.org/trac/mpi-forum-web/attachment/ticket/349/review-349-402-404.pdf
> >> 
> >> 
> >> 
> >> Read by: David Goodell
> >> #369 - Add same_disp_unit info key for RMA window creation
> >> 
> >> 
> >> 
> >> https://svn.mpi-forum.org/trac/mpi-forum-web/attachment/ticket/369/mpi-report.2.pdf
> >> 
> >> 
> >> 
> >> Read by: Pavan Balaji
> >> 
> >> Please add these to the agenda.  Unfortunately, I will not be able
> >> to
> >> attend this meeting, so I have included a contact person for each
> >> ticket.
> >> 
> >> 
> >> Thanks!
> >>  ~Jim.
> >> _______________________________________________
> >> mpi-forum mailing list
> >> mpi-forum at lists.mpi-forum.org
> >> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpi-forum
> > 
> > --
> > 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: Room
> > 1.307)
> 
> 
> 
> --
> Jeff Hammond
> jeff.science at gmail.com
> _______________________________________________
> mpiwg-rma mailing list
> mpiwg-rma at lists.mpi-forum.org
> http://lists.mpi-forum.org/mailman/listinfo.cgi/mpiwg-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: Room 1.307)