kernel : Process states

kernel : Process states

quoted from : professional linux kernel architecture by Wolfgang mauerer
page. 44

1.TASK_RUNNING : means that a task is in arunnable state. It does NOT mean that a CPU is actually allocated.
The task can wait until it is selecte by the scheduler. This state guarantees that the process really is ready to run and is not waiting for an externel event.

2. TASK_INTERRUPTIBLE is set for s sleeping process that is waiting for some event or other. When the kernel signals to the process that the event has occurred, it is placed in the TASK_RUNNING state and may resume execution as soon as it is selected by the scheduler.

3. TASK_UNINTERRUPTIBLE is used for sleeping process DISABLED on the instructions of the kernel. They may NOT be woken by external signals, only by the kernel itself.

4. TASK_STOPPED indicated that the process was STOPPED on purpose -- by a debugger, eg.

5. TASK_TRACED is NOT a process state per se -- it is used to distinguish stopped tasks that are currently being traced ( using the ptrace mechanism) from regular stopped tasks.