can you tell me some simple example of “uninterruptible sleep” state? I'm learning unix and example with NFS is not much obvious for me.
The difference between interruptible and uninterruptible sleep is that the latter ignores signals:
Linux has two fundamental ways in which a process can be put to sleep. A process which is placed in the TASK_INTERRUPTIBLE state will sleep until either (1) something explicitly wakes it up, or (2) a non-masked signal is received. The TASK_UNINTERRUPTIBLE state, instead, ignores signals; processes in that state will require an explicit wakeup before they can run again.