Re: Next round: revised futex(2) man page for review
From: Michael Kerrisk (man-pages)
Date: Sat Aug 08 2015 - 02:56:20 EST
On 07/28/2015 11:03 PM, Thomas Gleixner wrote:
> On Tue, 28 Jul 2015, Peter Zijlstra wrote:
>
>> On Tue, Jul 28, 2015 at 10:23:51PM +0200, Thomas Gleixner wrote:
>>
>>>> FUTEX_WAKE (since Linux 2.6.0)
>>>> This operation wakes at most val of the waiters that are
>>>> waiting (e.g., inside FUTEX_WAIT) on the futex word at the
>>>> address uaddr. Most commonly, val is specified as either
>>>> 1 (wake up a single waiter) or INT_MAX (wake up all waitâ
>>>> ers). No guarantee is provided about which waiters are
>>>> awoken (e.g., a waiter with a higher scheduling priority
>>>> is not guaranteed to be awoken in preference to a waiter
>>>> with a lower priority).
>>>
>>> That's only correct up to Linux 2.6.21.
>>>
>>> Since 2.6.22 we have a priority ordered wakeup. For SCHED_OTHER
>>> threads this takes the nice level into account. Threads with the same
>>> priority are woken in FIFO order.
>>
>> Maybe don't mention the effects of SCHED_OTHER, order by nice value is
>> 'wrong'.
>
> Indeed.
>
>> Also, this code seems to use plist, which means it won't do the right
>> thing for SCHED_DEADLINE either.
>>
>> Do we want to go fix that?
>
> I think so.
So, no change to this piece of text then?
Cheers,
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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