Write Streaming Mode

Write Streaming Mode

数据从PCI总线，IO Controller直接到Memory Controller，而不经过cache的模式。不妨翻译为写穿透？或者流式写？

参考Cortex_A55手册——Write Streaming Mode一节。

在aarch64下通过CPUECTLR_EL1寄存器使Core进入Write streaming mode，进入该模式后Bus Interface Unit（BIU）的作用

When a core has dropped into write streaming mode, the BIU continues to monitor the bus traffic and will signal to the L2 for it to go into write streaming mode when a further number of full cache line writes are seen.

就是说BIU在打开Write streaming模式后一直监控总线，如果出现大量的连续写，那么在一定的数量（CPUECTRL_EL1寄存器中指定）之后，写入的cacheline大小的数据就绕过cache。