On Nov 12, 2013, at 19:47 , Jeff Squyres (jsquyres) <jsquy...@cisco.com> wrote:
> On Nov 12, 2013, at 4:42 AM, George Bosilca <bosi...@icl.utk.edu> wrote: > >>> 2. In the 64 bit case, you'll have a difficult time extracting the MPI >>> status values from the 8-byte INTEGERs in the status array in Fortran >>> (because the first 2 of 3 each really be 2 4-byte integers). >> >> My understanding is that in Fortran explicitly types variables will retain >> their expected size. Thus, instead of declaring >> >> INTEGER :: status[MPI_STATUS_SIZE] >> >> one should go for >> >> INTEGER*4 :: status[MPI_STATUS_SIZE] >> >> This should make it work right now. > > You are correct. That’s a good workaround. Not good … temporary ;) >> However, it is a non-standard solution, and we should fix the status >> handling internally in Open MPI. >> >> Looking at the code I think that correctly detecting the type of our >> ompi_fortran_integer_t during configure (which should be a breeze if the >> correct flags are passed) should solve all issues here as we are protecting >> the status conversion between C and Fortran. > > Not quite. We do already correctly determine ompi_fortran_integer_t as a C > "int" or "long long" (that's what I saw yesterday when I tested this myself). > > However, the key here is that MPI_STATUS_SIZE is set to be the size of a > ***C*** MPI_Status (but expressed in units of Fortran INTEGER size -- so in > the sizeof(int)==sizeof(INTEGER)==4 case, MPI_STATUS_SIZE is 6. But in the > sizeof(int)==4, sizeof(INTEGER)==8 case, MPI_STATUS_SIZE is 3. > > That being said, we *could* change this so that MPI_STATUS_SIZE is always 6, > and have the C<—>Fortran status routines just do the Right Thing depending on > the size/type of ompi_fortran_integer_t. Indeed. We can have an Fortran MPI_Status (only in the Fortran interface) that will be 3 ompi_fortran_integer_t, and alter the translation macros to do the right thing (translate from C int to the chosen Fortran int). > Either way, as you say, it's a nonstandard solution. So I don't know which > way is "more correct". On the one hand, we've had it this way for *years* > (so perhaps there's code out there that uses the George workaround and is > working fine). But OTOH, it’s different than what you would have to do in > the non-dash-i8 case, and so we should make MPI_STATUS_SIZE be 6 and then > Fortran code will work identically (without INTEGER*4) regardless of whether > you used -i8 or not. Honestly, I think that most users will expect that an MPI compiled with -i8 will have the status as a 3 8 bytes integers and not some other weird combination depending on another layer of the library (compiled in a language lacking the subtlety of -i8 ;)). George. > > Shrug. > >> Jim, can you go in the include directory on your Open MPI installation and >> grep for the definition of ompi_fortran_integer_t please. >> >> George. >> >> >> _______________________________________________ >> users mailing list >> us...@open-mpi.org >> http://www.open-mpi.org/mailman/listinfo.cgi/users > > > -- > Jeff Squyres > jsquy...@cisco.com > For corporate legal information go > to:http://www.cisco.com/web/about/doing_business/legal/cri/ > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users
