Thank you for the clarification. Why is MPI_COMM_SELF not the correct communicator for MPI_Comm_spawn(). My application will have a single master only.
Also, can I merge the intercommunicator into an intracommunicator via MPI_Intercomm_merge(intercomm, 0, &intracomm) and use MPI_Bcast(..., 0, intracomm) instead of sending MPI_ROOT or 0 (root's rank in local group). Thanks. On 7/18/06, Bert Wesarg <wes...@informatik.uni-halle.de> wrote:
hi, yes sorry for my first reply, my words were to rough. a bcast for a intercomm works this way (in your words): - your masters want to send a buffer to your slaves - one of the masters must provide the MPI_ROOT as root in the MPI_BCAST call - all slaves must provide the rank of this MPI_ROOT as the root argument - all others ranks from the masters, must provide MPI_PROC_NULL as root so the buffer will be send from MPI_ROOT to all slaves if this isn't that clear, you should understand the concept of mpi intercomms. a good starting point could be the standard: http://www.mpi-forum.org/docs/mpi-11-html/node111.html by the way: * your one_int is never intitialized * i don't know if the MPI_COMM_SELF is the right comm for the MPI_COMM_SPAWN by bert wesarg s anwar wrote: > I don't think I blamed the implementation in any way in my original > email. My intent is to gain understanding of why my code does/should not > work. I assumed that I was not passing the correct intercommunicator. > However, I am at a loss on how to construct a proper intercommunicator > in this case. You have mentioned that I haven't defined any group to be > the root group. Could you care to elaborate on how can I make a group a > root group? > > Thanks. > > On 7/18/06, *Bert Wesarg* <wes...@informatik.uni-halle.de > <mailto:wes...@informatik.uni-halle.de>> wrote: > > Hi, > > s anwar wrote: > > Please see attached source file. > > > > According to my understanding of MPI_Comm_spawn(), the > intercommunicator > > returned is the same as it is returned by MPI_Comm_get_parent() in > the > > spawned processes. I am assuming that there is one intercommunicator > > which contains all the (spawned) child processes as well as the parent > > process. If this is the case, then why does an MPI_Bcast() using > such an > > intercommunicator wait indefinately? > > your code from line 75: > > MPI_Bcast(&one_int, 1, MPI_INT, 0, intercomm); > > from the mpi 2 standard "7.3.2.1 <http://7.3.2.1>. Broadcast" > > "If comm is an intercommunicator, then the call involves all > processes in > the intercommunicator, but with one group (group A) defining the root > process. All processes in the other group (group B) pass the same > value in > argument root, which is the rank of the root in group A. The root passes > the value MPI_ROOT in root. All other processes in group A pass the > value > MPI_PROC_NULL in root. Data is broadcast from the root to all > processes in > group B. The receive buffer arguments of the processes in group B > must be > consistent with the send buffer argument of the root." > > so, you define no group to be the root group (group A). i don't know > what > schould happen, when no root group is defined, but your code firstly > don't > conform to the standard, so don't blame the implementation first. > > by > bert wesarg > > _______________________________________________ > users mailing list > us...@open-mpi.org <mailto: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 _______________________________________________ users mailing list us...@open-mpi.org http://www.open-mpi.org/mailman/listinfo.cgi/users
