Apple Inc.
Cache Memory with Transient Storage for Cache Lines

Abstract:

Techniques are disclosed relating to caches that support transient storage fields for cache entries. In some embodiments, cache circuitry includes a set of multiple cache entries that each include a tag field and a data field. In some embodiments, transient storage circuitry includes a transient storage field for each of the multiple cache entries. In some embodiments, cache control circuitry stores received first data in the data field of a cache entry and stores received transient data in a corresponding transient storage field. In response to an eviction determination for the cache entry, however, the cache control circuitry may write the first data but not the transient data to a backing memory for the cache circuitry. In various embodiments, disclosed techniques may allow caching additional data that is transient without increasing bandwidth to the backing memory.