On Oct 30, 2013, at 4:35 PM, Jim Parker <jimparker96...@gmail.com> wrote:
> I have recently built a cluster that uses the 64-bit indexing feature of > OpenMPI following the directions at > http://wiki.chem.vu.nl/dirac/index.php/How_to_build_MPI_libraries_for_64-bit_integers That should be correct (i.e., passing -i8 in FFLAGS and FCFLAGS for OMPI 1.6.x). > My question is what are the new prototypes for the MPI calls ? > specifically > MPI_RECV > MPI_Allgathterv They're the same as they've always been. The magic is that the -i8 flag tells the compiler "make all Fortran INTEGERs be 8 bytes, not (the default) 4." So Ralph's answer was correct in that all the MPI parameters are INTEGERs -- but you can tell the compiler that all INTEGERs are 8 bytes, not 4, and therefore get "large" integers. Note that this means that you need to compile your application with -i8, too. That will make *your* INTEGERs also be 8 bytes, and then you'll match what Open MPI is doing. > I'm curious because some off my local variables get killed (set to null) upon > my first call to MPI_RECV. Typically, this is due (in Fortran) to someone > not setting the 'status' variable to an appropriate array size. If you didn't compile your application with -i8, this could well be because your application is treating INTEGERs as 4 bytes, but OMPI is treating INTEGERs as 8 bytes. Nothing good can come from that. If you *did* compile your application with -i8 and you're seeing this kind of wonkyness, we should dig deeper and see what's going on. > My review of mpif.h and mpi.h seem to indicate that the functions are defined > as C int types and therefore , I assume, the coercion during the compile > makes the library support 64-bit indexing. ie. int -> long int FWIW: We actually define a type MPI_Fint; its actual type is determined by configure (int or long int, IIRC). When your Fortran code calls C, we use the MPI_Fint type for parameters, and so it will be either a 4 or 8 byte integer type. -- Jeff Squyres jsquy...@cisco.com For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
