What does the 'M' state in MESI protocol signify for a cache line?
The Modified (M) state indicates that a cache has modified the data in its cache line. This copy is therefore the only correct, most up-to-date version, and it is dirty (inconsistent with main memory). Before any other cache or the CPU can read the data, the cache holding the 'M' copy is responsible for writing the data back to main memory.
