MSI protocol

For example, bus architectures often perform snooping, where the read request is broadcast to all of the caches.

These include: State Transitions: This protocol is similar to the one used in the SGI 4D machine.

[3] Modern systems use variants of the MSI protocol to reduce the amount of traffic in the coherency interconnect.

The MESI protocol adds an "Exclusive" state to reduce the traffic caused by writes of blocks that only exist in one cache.

The MOSI protocol adds an "Owned" state to reduce the traffic caused by write-backs of blocks that are read by other caches.