disk wait mystery

[Warren Block]

On Thu, 31 Jan 2013, Gary Palmer wrote:

> On Thu, Jan 31, 2013 at 07:12:44AM -0700, Warren Block wrote:
>> On Wed, 30 Jan 2013, Andrew wrote:
>>
>>> On 30 Jan 2013, at 17:05, Brett Wynkoop wrote:
>>>
>>>> I appreciate the education on this point!  I wonder if this should be
>>>> considered a man page bug?
>>>
>>> The man page does say "(or other short term, uninterruptible) wait". I
>>> don't know what sort of wait the kernel threads may or may not be in
>>> but if they are in one, and its short-term then the man page is
>>> correct. Maybe an FAQ entry though.
>>
>> If the man page is misleading or incomplete, it should be fixed.  Based
>> on the source, the mention of disk at the start is misleading.  Maybe:
>>
>> D       Marks a process in short term, uninterruptible wait.
>>
>> Or
>>
>> D       Marks a process in short term, uninterruptible wait (typically,
>>          disk wait).
>>
>> Which explains the "D" but may reintroduce the confusion.
>
> D       Marks a process in short term, uninterruptible wait (In non-kernel
>        processes, this is typically waiting on disk I/O)

The followup question that creates is "what are kernel threads waiting
on?"  Which is covered by the uninterruptable part earlier.  I think the
"typically" handles it without creating more questions.

Leaving out the redundant "Marks a process" wording:

D	Disk wait, or other short-term, uninterruptable wait.

"disk wait" was the original term in that man page.  "Also shown for 
uninterruptable kernel threads." is just repeating.