Energy optimized cache memory architecture exploiting spatial locality

摘要

Aspects of the present invention provide a “SuperTag” cache that manages cache at three granularities: (i) coarse grain, multi-block “super blocks,” (ii) single cache blocks and (iii) fine grain, fractional block “data segments.” Since contiguous blocks have the same tag address, by tracking multi-block super blocks, the SuperTag cache inherently increases per-block tag space, allowing higher compressibility without incurring high area overheads. To improve compression ratio, the SuperTag cache uses variable-packing compression allowing variable-size compressed blocks without requiring costly compactions. The SuperTag cache also stores data segments dynamically. In addition, the SuperTag cache is able to further improve the compression ratio by co-compressing contiguous blocks. As a result, the Super Tag cache improves energy and performance for memory intensive applications over conventional compressed caches.

主权项

1. A cache memory system comprising:
a cache memory storing a plurality of data segments, wherein the data segments are compressed from a multi-block including contiguous data blocks originating from a higher level of memory; a tag, memory array coupled to the cache memory, wherein the tag memory array stores a plurality of tag addresses with each tag address corresponding to a multi-block originating from the higher level of memory; and a back pointer array coupled to the cache memory and the tag memory array, wherein the back pointer array stores a plurality of back pointer entries with each back pointer entry corresponding to a data segment in the cache memory and each back pointer entry identifying a multi-block associated with a tag address in the tag memory array and a data block of the multi-block compressed to form the data segment; wherein the data segments are stored non-contiguously in the cache memory.