There are not many situations in which broadcasting is more effective than a directory-based coherency system: even if you have a high number of sharers, each sharer will get the lock to write relatively infrequently, so it doesn't usually matter what the new value is, just that a value is wrong.
There are not many situations in which broadcasting is more effective than a directory-based coherency system: even if you have a high number of sharers, each sharer will get the lock to write relatively infrequently, so it doesn't usually matter what the new value is, just that a value is wrong.