Further, the guest operating system has the most information about the workload's memory use and should be able to make the best page replacement decisions.
更进一步，客户操作系统具有最多的关于工作负载的内存使用的信息，应该能做出最好的页面替换决策。
2
If the page is unmodified, the page replacement daemon can simply mark the physical memory block as free, and the physical memory block can then be re-used for another page.
Because the page replacement algorithm is always looking for free frames while it is doing its scanning on systems with a lot of memory, the number of frames to scan can be significant.