When a modified permanent storage page needs to be paged out (moved from memory to disk), it is written to a file system.
当经过修改的永久存储分页需要换出(从内存移动到磁盘)的时候，会将它写入到文件系统中。
2
The page section in the output indicates current paging status of your system; pi column indicates number of pages read into the memory and po column indicates number of pages paged out of the memory.
输出的 page 部分指示系统的当前分页状态；pi 列指示读入内存的页数目，而 po 列则指示移出内存的页数目。