MSI Protocol
•Rdx means that the cache
holds a modified value of the location and asks
for exclusive permission to read
•Reply means put the value on the bus for another processor to
read
PrWr/BusRdx
BusRd/Reply
PrRd/-
BusRd/-
BusRdx/--
PrRd/BusRd
PrWr/BusRdx
PrRd/--
PrWr/--
M
S
I
BusRdx/Reply
Conceptually: Manage dirty value within caches