Applying the WT Protocol
•Consider the transactions
PrRd/--
PrWr/BusWr
PrWr/BusWr
V
I
PrRd/BusRd
BusWr/--
P1 reads a into its cache
P3 reads a into its cache
P1 changes a to 5 and writes through to main memory
P3 sees the action and invalidates the location
P2 reads a into its cache
P1 : I --> V  PrRd/BusRd P3 : I --> V  PrRd/BusRd P1 : V --> V PrWr/BusWr P3 : V --> I   BusWr/--     P2 :  I --> V  PrRd/BusRd