1. A method for processing packets in a system that comprises a plurality of interconnected processing cores, the method comprising: receiving packets into one or more queues that are each associated with a rate limit; providing a logical hierarchy of a plurality of levels of nodes, with nodes in the hierarchy associated with the one or more queues; selecting nodes for inclusion in a set of the associated nodes according to a sum of rate-limits of the selected nodes, the selected nodes provide a maximum rate at which at least portions of packets are transmitted from a first processor core; mapping the set of the associated nodes to the first processor core based on a first level of the hierarchy and based on at least one rate associated with a node not in the set of the associated nodes for performing a first function; mapping the set of the associated nodes to a second, different processor core for performing a second, different function on the set of the associated nodes by the second processor core; processing the received packets in the mapped first processor core according to the first function; and processing the received packets in the mapped second processor core according to the second, different function.