If you use only non-blocking communications I don't see how the behavior you describe can happen in the code of Open MPI. There might be something else going on there.
George. On Apr 27, 2013, at 00:14 , Stephan Wolf <wol...@in.tum.de> wrote: > Hi, > > I have encountered really bad performance when all the nodes send data > to all the other nodes. I use Isend and Irecv with multiple > outstanding sends per node. I debugged the behavior and came to the > following conclusion: It seems that one sender locks out all other > senders for one receiver. This sender releases the receiver only when > there are no more sends posted or a node with lower rank, wants to > send to this node (deadlock prevention). As a consequence, node 0 > sends all its data to all nodes, while all others are waiting, then > node 1 sends all the data, … > > What is the rationale behind this behaviour and can I change it by > some MCA parameter? > > Thanks > > Stephan > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users
