Caches have accounted for a significant fraction of the over- all chip dynamic energy. For instance, the Alpha 21264 CPU consumes about 16% energy in caches, even without on-chip L2 caches. The Pentium Pro consumes about 33% of the chip power in instruction fetch and d-cache together. Large L2 caches typically consume even more power. For example, the Intel 200 MHz P2 processor with 256 KB L2 Cache has a typical thermal design power consumption of 27.3W. When the L2-Cache size is increased to
1MB, the typical power consumption for the same processor jumps In real situation, the MRU information is not available. Even larger average latency will be introduced in order to wait for the prediction information to be generated to 47W, a 72% increase. In today’s computer systems, even larger caches are packed into the processor. Thus lowering the power-consumption of the cache system is an important research topic.