Storage overhead can be reduced using limited pointer schemes and sparse directories. However, both of these workarounds introduce other problems. Limited pointer schemes can only store a fixed number of sharers, and sparse directories have the additional cost of sending invalidation messages through the whole linked list. These workarounds are more complicated to implement as well, so unless we have a very large number of processors and limited memory, it is not worth it.
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All processors/caches much communicate via the interconnect. The interconnect traffic limits the scalability of snooping based approaches.
Storage overhead can be reduced using limited pointer schemes and sparse directories. However, both of these workarounds introduce other problems. Limited pointer schemes can only store a fixed number of sharers, and sparse directories have the additional cost of sending invalidation messages through the whole linked list. These workarounds are more complicated to implement as well, so unless we have a very large number of processors and limited memory, it is not worth it.
All processors/caches much communicate via the interconnect. The interconnect traffic limits the scalability of snooping based approaches.