RetroBBS - comp.unix.programmer - Re: Ordering of sem

Re: Ordering of sem_wait waiters

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Date: Wed, 9 Mar 2022 19:27:46 -0800 (PST)
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Subject: Re: Ordering of sem_wait waiters
From: zhtzeng@gmail.com (Tseng ZH)
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by: Tseng ZH - Thu, 10 Mar 2022 03:27 UTC

Kaz Kylheku 在 2017年2月24日星期五上午11:20:10 [UTC+8] 的信中寫道：
> On 2017-02-24, zhan...@conew.com <zhan...@conew.com> wrote:
> > 在 2012年4月25日星期三 UTC+8下午11:17:09，Noob写道：
> ^^^^^
> >> Hello everyone,
> >>
> >> The (proprietary) OS I've been working with provides two "types"
> >> of semaphores: fifo or prio.
> >
> > This discussion is useful.
>
> It's also almost five years old and not going on any more.

According to below link, I think it doesn't guarantee any order.
https://man7.org/linux/man-pages/man2/futex.2.html

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
waiters). 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).

Slowly and surely the unix crept up on the Nintendo user ...

devel / comp.unix.programmer / Re: Ordering of sem_wait waiters

Subject	Author
Re: Ordering of sem_wait waiters	Tseng ZH