The special replacemetlt algorithin of this information cache assures that the nodes in the cache are the k most overloaded nodes and the k most underloaded nodes in the cluster system 信息cache通过特殊的替换算法，保证两个cache中的信息分别为系统中负载最大的k个超载节点的信息和负载最小的k个欠载节点的信息。
