Re: [OMPI users] multi-threaded programming

[Eugene Loh]

Durga Choudhury wrote: A follow-up question (and pardon if this sounds stupid) is this: If I want to make my process multithreaded, BUT only one thread has anything to do with MPI (for example, using OpenMP inside MPI), then the results will be correct EVEN IF #1 or #2 of Eugene holds true. Is this correct? I believe this is thoroughly covered by the standard (though I suppose the same could have been said about my question). In any case, for your situation, initialize MPI with MPI_Init_thread().  Ask for thread level MPI_THREAD_FUNNELED and check that that level is provided.  That should cover your case.  See the man page for MPI_Init_thread().  My question should not have anything to do with your case. On Tue, Mar 8, 2011 at 12:34 PM, Eugene Loh <eugene....@oracle.com> wrote: Let's say you have multi-threaded MPI processes, you request MPI_THREAD_MULTIPLE and get MPI_THREAD_MULTIPLE, and you use the self,sm,tcp BTLs (which have some degree of threading support).  Is it okay to have an [MPI_Isend|MPI_Irecv] on one thread be completed by an MPI_Wait on another thread?  I'm assuming some sort of synchronization and memory barrier/flush in between to protect against funny race conditions. If it makes things any easier on you, we can do this multiple-choice style: 1)  Forbidden by the MPI standard. 2)  Not forbidden by the MPI standard, but will not work with OMPI (not even with the BTLs that claim to be multi-threaded). 3)  Works well with OMPI (provided you use a BTL that's multi-threaded). It's looking like #2 to me, but I'm not sure. _______________________________________________ users mailing list us...@open-mpi.org http://www.open-mpi.org/mailman/listinfo.cgi/users _______________________________________________ users mailing list us...@open-mpi.org http://www.open-mpi.org/mailman/listinfo.cgi/users