• David Goodell's avatar
    [svn-r4001] Compute sub-communicator context IDs from the parent's context ID. · 85ae9cf1
    David Goodell authored
    This change removes the MPIR_Allreduces that were added to MPI_Init time as part
    of the SMP collectives work.  It also brings the number of MPI_Allreduces on
    each communicator creation back down to 1 instead of 3.  It does this by shaving
    2 bits from the context ID to indicate parent, intranode, or internode.
    
    This change also removes one of the context suffix (also called offset) bits
    from context IDs, for a final number of 1 bit.
    
    The net change in the context ID space after this change is a reduction by a
    factor of 2 (1 bit).
    
    Reviewed by buntinas@.
    85ae9cf1