Cache memory with reduced power consumption mode

A method of operating a cache memory system, comprising:

• receiving an indicator that a cache memory in an operable power consumption state is to be placed into a reduced power consumption state, the cache memory organized as a set of cache lines and a set of tag entries, the tag entries providing an index to the cache lines in the cache memory;
• based at least in part on the indicator, copying at least a set of valid cache lines from the cache memory to a memory located separate from the cache memory based on the index such that locations in the set of tag entries are related to corresponding location in the memory;
• placing the cache memory in the reduced power consumption state, wherein the set of cache lines are not accessed while the cache memory is in the reduced power consumption state;
• while the cache memory is in the reduced power consumption state, receiving a cache access request for a cache line;
• while the cache memory is in the reduced power consumption state, performing, using the set of tag entries, a tag lookup corresponding to the cache access request;
• and
• based on a result of the tag lookup, determining a location in the memory that corresponds to the cache line and retrieving data at the location in the memory corresponding to the cache line.

A method of operating a processing system, comprising:

• receiving, at a cache memory and while the cache memory is in a first power consumption state, a first cache access request corresponding to a cache line stored in a storage array of the cache memory, the cache memory including a tag array providing an index that is used to determine whether the storage array holds the cache line;
• before placing the cache memory in a second power consumption state, copying the cache line to an archive memory that is separate from the cache memory;
• placing the cache memory in the second power consumption state, the storage array not operable while the cache memory is in the second power consumption state, the tag array being operable while the cache memory is in the second power consumption state such that a location of the cache line in the storage array is related to a corresponding location in the archive memory based on the index;
• while the cache memory is in the second power consumption state, receiving a second cache access request corresponding to the cache line;
• and
• based at least in part on the second cache access request, and while the cache memory is in the second power consumption state, determining, using the tag array, the corresponding location of the cache line in the archive memory and retrieving data at the corresponding location of the cache line in the archive memory.