Power control for cache structures

An apparatus, comprising:

• a power management unit configured to:
• receive an indication from a cache having a set of tag structures in response to the cache determining that the cache does not include valid data;
• in response to the indication, power down the cache and a duplicate set of tag structures corresponding to the set of tag structures in the cache;
• and
• power up the duplicate set of tag structures in response to a request for data missing in the cache.

An apparatus, comprising:

• a cache including a first set of tag structures, wherein the cache is configured to:
• store tag data in the first set of tag structures;
• determine whether the cache contains valid data;
• and
• in response to determining that the cache does not contain valid data, issue a request to be powered down;
• a second set of tag structures configured to store a duplicate copy of the tag data;
• and
• wherein the apparatus is configured to power down the cache and the second set of tag structures in response to the request.

An apparatus, comprising:

• a coherence point configured to maintain cache coherency between one or more caches and a memory, including maintain a duplicate set of tag structures for a set of tag structures in the one or more caches;
• and
• a power management unit is configured to:
• receiving an indication that the one or more caches do not include valid data;
• in response to the indication:
• reduce power to the one or more caches;
• and
• reduce power to at least a portion of the coherence point, wherein the portion includes the duplicate set of tag structures;
• and
• power up the portion of the coherence point in response to a request for data missing in one of the one or more caches.

A method, comprising:

• a cache of a processor determining that the cache does not include valid data, wherein the cache includes a set of tag structures storing tag data;
• in response to the determining, the cache sending, to a power management unit, a request to reduce power to the cache and a duplicate set of tag structures storing the tag data;
• and
• in response to the request, the power management unit reducing power to the cache and the duplicate set of tag structures.