1. An information processing system comprising: a plurality of managed servers for providing access to a storage device and for processing information; a plurality of cooling machines for cooling said servers; and a power-saving controller for sending and receiving information to and from said servers via a network to detect workload of said servers and for controlling said cooling machines and said servers in accordance with a detection result, wherein said power-saving controller controls the cooling ability of said cooling machines in accordance with the workload of said servers and also controls task allocation with respect to said servers.