Editing Bus snooping (section)

== How it works ==
When specific data are shared by several caches and a processor modifies the value of the shared data, the change must be propagated to all the other caches which have a copy of the data. This change propagation prevents the system from violating [[Cache coherence|cache coherency]]. The notification of data change can be done by bus snooping. All the snoopers monitor every transaction on a bus. If a transaction modifying a shared cache block appears on a bus, all the snoopers check whether their caches have the same copy of the shared block. If a cache has a copy of the shared block, the corresponding snooper performs an action to ensure cache coherency. The action can be a flush or an [[Cache invalidation|invalidation]] of the cache block. It also involves a change of cache block state depending on the cache coherence protocol.<ref name=":0">{{Cite book|title=Fundamentals of Parallel Computer Architecture|last=Yan Solihin|year=2016|pages=239–246}}</ref>