Decoupled sectored caches: conciliating low tag implementation cost and low miss ratio

Sectored caches have been used for many years in order to reconcile low tag array size and small or medium block size. In a sectored cache, a single address tag is associated with a sector consisting on several cache lines, while validity, dirty and coherency tags are associated with each of the inner cache lines. Usually in a cache, a cache line location is statically linked to one and only one address tag word location. In the decoupled sectored cache introduced in the paper, this monolithic association is broken; the address tag location associated with a cache line location is dynamically chosen at fetch time among several possible locations. The tag volume on a decoupled sectored cache is in the same range as the tag volume in a traditional sectored cache; but the hit ratio on a decoupled sectored cache is very close to the hit ratio on a non-sectored cache. A decoupled sectored cache will allow the same level of performance as a non-sectored cache, but at a significantly lower hardware cost.<<ETX>>