Write-back Cache Cachet块状态 PrRd/- Invalid, Valid(clean), Modified(dirty PwR/ Processor/ Cache操作 PrRd, PrWr, block Replace M 总线事务 Bus read(BusRd), Write-Back BusWB) PrWr/- 仅传送 cache-b|ock Replace/BusWB PwR/BusRd 针对 Cache-致性的块状态调整 Replace/ Treat valid as shared PrRd/- Treat modified as Exclusive PrRd/BusRd ·引入新的总线事务 Bus Read-eXclusive(BusRdX) 其基本动作是:读进并修改 2021/2/1 计算机体系结构Write-back Cache • Cache块状态 – Invalid, Valid (clean), Modified (dirty) • Processor / Cache 操作 – PrRd, PrWr, block Replace • 总线事务 – Bus Read (BusRd), Write-Back (BusWB) – 仅传送cache-block • 针对Cache一致性的块状态调整 – Treat Valid as Shared – Treat Modified as Exclusive • 引入新的总线事务 – Bus Read-eXclusive (BusRdX) – 其基本动作是：读进并修改 2021/2/1 计算机体系结构 8 PrRd/— PrWr/— V M I Replace/BusWB PrWr/— PrRd/BusRd Replace/— PrWr/BusRd PrRd/—