The Dirty-Block Index
On-chip caches maintain multiple pieces of metadata about each cached block - e.g., dirty bit, coherence information, ECC. Traditionally, such metadata for each block is stored in the corresponding tag entry in the tag store. While this approach is simple to implement and scalable, it necessitates a full tag store lookup for any metadata query - resulting in high latency and energy consumption. The authors find that this approach is inefficient and inhibits several cache optimizations. In this paper, they propose a new way of organizing the dirty bit information that enables simpler and more efficient implementations of several optimizations.