Coherency protocol for computer cache

摘要

A lower level cache detects when a line of memory has been evicted from a higher level cache. The cache coherency protocol for the lower level cache places the line into a special state. If a line in the special state is evicted from the lower level cache, the lower level cache knows that the line is not cached at a higher level, and therefore a back-invalidate transaction is not needed. Reducing the number of back-invalidate transactions improves the performance of the system.