参考大牛:
http://www.searchtb.com/2014/04/%E5%BD%93cpu%E9%A3%99%E5%8D%87%E6%97%B6%EF%BC%8C%E6%89%BE%E5%87%BAphp%E4%B8%AD%E5%8F%AF%E8%83%BD%E6%9C%89%E9%97%AE%E9%A2%98%E7%9A%84%E4%BB%A3%E7%A0%81%E8%A1%8C.html