chapter 9

什么是 write-back vs write-through (需要回去看第6章)

The data on disk is partitioned into blocks that serve as the transfer units between the disk and the main memory. Virtual memory systems handle this by partitioning the virtual memory into fixed-size blocks called virtual pages(VPs). Physical memory is partitioned into physical pages also P bytes in size.

所以pages就是对应disk上面的partition, 是transfer units between disk and main memory

These capabilities are provided by a combination of operating system software, address translation hardware in the MMU (memory management unit), and a data structure stored in physical memory known as a page table that maps virtual pages to physical pages. The address translation hardware

In virtual memory parlance, a DRAM cache miss is known as a page fault.

真的要首先理解各种名词……不然看起来感觉很高深，实际上只是个定义

Figure 9.6 shows the state of our example page table before the fault.

The CPU has referenced a word in VP 3, which is not cached in DRAM. The address translation hardware reads PTE 3 from memory, infers from the valid bit that VP 3 is not cached, and triggers a page fault exception. The page fault exception invokes a page fault exception handler in the kernel, which selects a victim page

这里exception就是第八章讲到的exception，是计算机实现进程切换的底层原理。让program counter 转移到另一个位置的实现方法

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