[MPI3 Fortran] MPI non-blocking transfer

[Rolf Rabenseifner]

I do not understand, why the DD trick should not work together
in the cases of
  MPI_Isend + MPI_Wait + DD (to prohibit overwriting before MPI_Wait)
and
  MPI_Irecv + MPI_Wait + DD (to prohibit access to buf before 
MPI_Wait)

The trick is part of the MPI standard.
Your email may mean that the MPI standard is broken.
The advice to users is always to use all other methods mentioned
in the standard (e.g. also COMMON blocks), before using VOLATILE.

Best regards
Rolf


On Mon, 9 Feb 2009 15:06:51 -0800
  Aleksandar Donev <donev1 at llnl.gov> wrote:
> On Monday 09 February 2009 14:57, Rolf Rabenseifner wrote:
>>       2.3 The existing solution must continue to work, i.e.,
>>           all existing and correct MPI applications must continue
>>           to work.
> There is no "existing solution", unless you count VOLATILE, which is 
> only standard as of Fortran 2003. As you say, 
>>       2.4 It is not my goal to automatically correct existing wrong
>>           MPI applications, i.e., applications without the DD trick
> the DD thing is a trick (I call them hacks), and actually does not 
>solve 
> the full problem, e.g., Nick has pointed out that problems can occur 
>at 
> the site of the call to MPI_Isend, *not* just the site of the wait 
>(but 
> the cases when it fails are marginal and likely do not happen often 
> enough to notice).
> Best,
> Aleks
> -- 
> Aleksandar Donev, Ph.D.
> Lawrence Postdoctoral Fellow @ Lawrence Livermore National 
>Laboratory
> High Performance Computational Materials Science and Chemistry
> E-mail: donev1 at llnl.gov
> Phone: (925) 424-6816  Fax: (925) 423-0785
> Address: P.O.Box 808, L-367, Livermore, CA 94551-9900
> Web: http://cherrypit.princeton.edu/donev

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)