Cache coherence is a concept used in systems with multiple processors and shared memory to ensure uniformity in the data stored across different local caches. Since each processor has distinct cache memory, different copies of the same memory block may be available on different caches, creating inconsistent data.

So, if one copy stored in one processor is updated or changed, all other copies must be updated or changed to avoid inconsistency. Cache coherence ensures all processors have a consistent memory view by updating each cache with any changes made to one copy on time.

Cache Coherence Protocols in a Multiprocessor System

Let’s discuss the above terms:

Cache Coherence Mechanisms