hi, s anwar wrote: > 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. yes for a single master this should be the same, but never try this. > > 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). dito, never try this, but it should work
bye bert wesarg > > Thanks. > > On 7/18/06, *Bert Wesarg* <wes...@informatik.uni-halle.de > <mailto: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 > <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> > > <mailto: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> > <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> <mailto: > 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 <mailto:us...@open-mpi.org> > > http://www.open-mpi.org/mailman/listinfo.cgi/users > _______________________________________________ > 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
