There may be ranks that have no clusters at all or far fewer clusters than that rank has the memory to accommodate. When attempting to swap, it should be allowed to swap a whole cluster from an overloaded rank with nothing from the underloaded rank (i.e., move a whole cluster from an overloaded to an underloaded rank even if there is nothing there to swap with).
There may be ranks that have no clusters at all or far fewer clusters than that rank has the memory to accommodate. When attempting to swap, it should be allowed to swap a whole cluster from an overloaded rank with nothing from the underloaded rank (i.e., move a whole cluster from an overloaded to an underloaded rank even if there is nothing there to swap with).