Sorry for the delay in replying. If you have non-contiguous buffers, you might want to investigate using MPI datatypes to describe the memory that you want to send/receive. Google around; you'll find bunches of tutorials on these kinds of things.
However, be aware that for a large 2D array, this generally only works well if your 2D array is uniformly distributed throughout memory. It would be best if you could actually malloc/new your 2D array as one giant 1D array and then setup the 2nd dimension/row pointers to point to the Right Places in that 1D array. Then you can both treat it as a large, contiguous buffer as well as make your own custom datatypes (e.g., a datatype for columns in the array). On Apr 2, 2013, at 3:28 AM, Ng Shi Wei <nsw_1...@hotmail.com> wrote: > Dear all, > > I am new in OpenMPI and writing a parallel processing program using openmpi > in C++ language. I would like to use the function MPI_Allreduce() but my > sendbuf and recvbuf datatype are pointers/arrays (2D). > > Is it possible to pass in and out the pointers/arrays using the > MPI_Allreduce() ? > > If yes, hope can have some guidelines provided on how to write the command. > > Thanks in advance. > > Best Regards, > Shi Wei > _______________________________________________ > 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/
