1. A method for processing an atomic operation received by an intermediate cache coupled to one or more clients and to an external memory, the method comprising: receiving the atomic operation from a client, the atomic operation including an atomic command and an atomic data payload; transmitting the atomic command to a tag look-up unit; determining whether a cache line within a data cache unit associated with the atomic command is available; incrementing a cache line reference counter associated with the cache line; and transmitting the atomic command and the atomic payload data to an arithmetic logic unit residing external to the intermediate cache for processing.