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 <[email protected]> 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: [email protected] 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 [email protected] 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)