That's a great suggestion...Thanks! amb
-----Original Message----- From: users-boun...@open-mpi.org on behalf of Bowen Zhou Sent: Thu 9/23/2010 1:18 PM To: Open MPI Users Subject: Re: [OMPI users] "self scheduled" work & mpi receive??? > Hi All: > > I've written an openmpi program that "self schedules" the work. > > The master task is in a loop chunking up an input stream and handing off > jobs to worker tasks. At first the master gives the next job to the > next highest rank. After all ranks have their first job, the master > waits via an MPI receive call for the next free worker. The master > parses out the rank from the MPI receive and sends the next job to this > node. The jobs aren't all identical, so they run for slightly different > durations based on the input data. > > > > When I plot a histogram of the number of jobs each worker performed, the > lower mpi ranks are doing much more work than the higher ranks. For > example, in a 120 process run, rank 1 did 32 jobs while rank 119 only > did 2. My guess is that openmpi returns the lowest rank from the MPI > Recv when I've got MPI_ANY_SOURCE set and multiple sends have happened > since the last call. > > > > Is there a different Recv call to make that will spread out the data better? > > How about using MPI_Irecv? Let the master issue an MPI_Irecv for each worker and call MPI_Test to get the list of idle workers, then choose one from the idle list by some randomization? > > THANXS! > > amb > > > > > ------------------------------------------------------------------------ > > _______________________________________________ > 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
