A survey of cache coherence schemes for multiprocessors

Schemes for cache coherence that exhibit various degrees of hardware complexity, ranging from protocols that maintain coherence in hardware, to software policies that prevent the existence of copies of shared, writable data, are surveyed. Some examples of the use of shared data are examined. These examples help point out a number of performance issues. Hardware protocols are considered. It is seen that consistency can be maintained efficiently, although in some cases with considerable hardware complexity, especially for multiprocessors with many processors. Software schemes are investigated as an alternative capable of reducing the hardware cost.<>