那位操作系统知识扎实，帮？看看

nattyneat

If a page has to be read from\r\ndisk, it is called a hard or major page fault—otherwise, it is a soft or minor page\r\nfault. After a minor page fault has been resolved, the CPU switches back into user\r\nmode and restarts the current instruction. However, while a major page fault is\r\nbeing resolved, the CPU time may be used to service other processes.\r\n\r\n1。major page fault ：  \r\n   需要进行物理IO。\r\n2。soft page fault:\r\n     不需要进行物理IO。（什么情况下发生？）\r\n关于“CPU switches back into user\r\nmode and restarts the current instruction”\r\n不明白

nattyneat

anybody can give me a help???