On 08/22/2014 02:40 PM, Saliya Ekanayake wrote:
Yes, these are all MPI_DOUBLE
well, yeah, but since you are talking about copying into a "direct buffer" there must be something tricker about the layout than just N*M doubles.
sometimes people allocate 2d arrays by allocating one array of N elements, then allocating and storing an array of length M in each of the N slots.
(you can find a dozen of these types of questions on stackoverflow, for example)
if the java interface allows you to describe with an MPI Datatype, or if you were working in C or Fortran, you can construct an HINDEXED type (or with very new MPICH, HINDEXED_BLOCK) and send that instead of copying.
==rob
On Fri, Aug 22, 2014 at 3:38 PM, Rob Latham <r...@mcs.anl.gov <mailto:r...@mcs.anl.gov>> wrote: On 08/22/2014 10:10 AM, Saliya Ekanayake wrote: Hi, I've a quick question about the usage of Java binding. Say there's a 2 dimensional double array (size m x n) that needs to be sent to another rank. I see two options to get this done, 1. Copy values to a direct buffer of size m*n and send it 2. Copy values to a 1D array of size m*n and send it i have no idea about the java mpi bindings, but can you describe the type with an mpi datatype? ==rob I guess 2 would internally do the copying to a buffer and use it, so suggesting 1. is the best option. Is this the case or is there a better way to do this? Thank you, Saliya -- Saliya Ekanayake esal...@gmail.com <mailto:esal...@gmail.com> <mailto:esal...@gmail.com <mailto:esal...@gmail.com>> http://saliya.org _________________________________________________ users mailing list us...@open-mpi.org <mailto:us...@open-mpi.org> Subscription: http://www.open-mpi.org/__mailman/listinfo.cgi/users <http://www.open-mpi.org/mailman/listinfo.cgi/users> Link to this post: http://www.open-mpi.org/__community/lists/users/2014/08/__25130.php <http://www.open-mpi.org/community/lists/users/2014/08/25130.php> -- Rob Latham Mathematics and Computer Science Division Argonne National Lab, IL USA _________________________________________________ users mailing list us...@open-mpi.org <mailto:us...@open-mpi.org> Subscription: http://www.open-mpi.org/__mailman/listinfo.cgi/users <http://www.open-mpi.org/mailman/listinfo.cgi/users> Link to this post: http://www.open-mpi.org/__community/lists/users/2014/08/__25135.php <http://www.open-mpi.org/community/lists/users/2014/08/25135.php> -- Saliya Ekanayake esal...@gmail.com <mailto:esal...@gmail.com> Cell 812-391-4914 Home 812-961-6383 http://saliya.org _______________________________________________ users mailing list us...@open-mpi.org Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users Link to this post: http://www.open-mpi.org/community/lists/users/2014/08/25136.php
-- Rob Latham Mathematics and Computer Science Division Argonne National Lab, IL USA
