Hi Lewis, On Thu, Sep 23, 2010 at 9:38 AM, Lewis, Ambrose J. <ambrose.j.le...@saic.com> wrote: > 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. >
What is the time taken by each computation ? It is possible that computation time for longer tasks is much greater than computation time for shorter tasks ? > > > Is there a different Recv call to make that will spread out the data better? > > > > THANXS! > > amb > > > > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users >
