Amazon.com, Inc.
Intelligent hierarchical caching based on metrics for objects in different cache levels

Abstract:

A cache system may maintain size and/or request rate metrics for objects in a lower level cache and for objects in a higher level cache. When an L1 cache does not have an object, it requests the object from an L2 cache and sends to the L2 cache aggregate size and request rate metrics for objects in the L1 cache. The L2 cache may obtain a size metric and a request rate metric for the requested object and then determine, based on the aggregate size and request rate metrics for the objects in the L1 cache and the size metric and the request rate metric for the requested object in the L2 cache, an indication of whether or not the L1 cache should cache the requested object. The L2 cache provides the object and the indication to the L1 cache.