https://blog.xupeng.me/2009/07/09/linux-uninterruptible-sleep-state/
另linux进程状态:https://cnbin.github.io/blog/2015/06/24/linux-duo-jin-cheng-1/
D和Z比喻很形象:这些垃圾进程要么是求而不得,像怨妇一般等待资源(D),要么是僵而不死,像冤魂一样等待超度(Z)
http://stevenlee87.blog.51cto.com/996623/1210516