Storage Key Cache Proposal
Original Publication Date: 1988-Jul-01
Included in the Prior Art Database: 2005-Feb-15
This article describes a key cache that is mapped the same as the L2 data cache. For each line entry that is valid in the L2 cache there will be a corresponding key entry in the L2 key cache. This storage protection key cache has two advantages. The key cache will always get a hit unless there is a miss in the L2 cache. In the event of a miss in the L2 key cache, the key can be loaded from the key array while the line needed by the L2 cache is being loaded from L3 storage. The second advantage is that, because the key cache is mapped the same as the L2 cache, both caches can share the same directory and, thus, save a large portion of the logic needed to implement a key cache. The mapping that is required can be accomplished if the L2 cache is configured, as shown in the figure.