From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
To: Peter Zijlstra <peterz@infradead.org>
Cc: minyard@acm.org, linux-rt-users@vger.kernel.org,
Corey Minyard <cminyard@mvista.com>,
linux-kernel@vger.kernel.org, tglx@linutronix.de,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [PATCH RT v2] Fix a lockup in wait_for_completion() and friends
Date: Tue, 14 May 2019 17:25:21 +0200 [thread overview]
Message-ID: <20190514152521.2gz6w2bahhgkxav7@linutronix.de> (raw)
In-Reply-To: <20190514113538.GL2589@hirez.programming.kicks-ass.net>
On 2019-05-14 13:35:38 [+0200], Peter Zijlstra wrote:
> On Tue, May 14, 2019 at 11:12:19AM +0200, Sebastian Andrzej Siewior wrote:
> > On 2019-05-14 10:43:56 [+0200], Peter Zijlstra wrote:
> > > Now.. that will fix it, but I think it is also wrong.
> > >
> > > The problem being that it violates FIFO, something that might be more
> > > important on -RT than elsewhere.
> >
> > Wouldn't -RT be more about waking the task with the highest priority
> > instead the one that waited the longest?
>
> Possibly, but that's a far larger patch. Also, even with that
> completions do not avoid inversions and thus don't really make nice RT
> primitives anyway.
See. So it does not really matter if a particular waiter ends up at the
end of the queue.
Anyway, I don't really think we need this but if you want it, let me add
it.
What about the other question I had regarding completion_done()?
Sebastian
next prev parent reply other threads:[~2019-05-14 15:25 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-08 20:57 [PATCH v2] Fix a lockup in wait_for_completion() and friends minyard
2019-05-09 16:19 ` [PATCH RT " Sebastian Andrzej Siewior
2019-05-09 17:46 ` Corey Minyard
2019-05-14 8:43 ` Peter Zijlstra
2019-05-14 9:12 ` Sebastian Andrzej Siewior
2019-05-14 11:35 ` Peter Zijlstra
2019-05-14 15:25 ` Sebastian Andrzej Siewior [this message]
2019-05-14 12:13 ` Corey Minyard
2019-05-14 15:36 ` Sebastian Andrzej Siewior
2019-05-15 16:22 ` Corey Minyard
2019-06-26 10:35 ` Peter Zijlstra
2019-05-09 19:33 minyard
2019-05-09 19:51 ` Steven Rostedt
2019-05-10 10:33 ` Sebastian Andrzej Siewior
2019-05-10 12:08 ` Corey Minyard
2019-05-10 12:26 ` Sebastian Andrzej Siewior
2019-06-29 1:49 ` Steven Rostedt
2019-07-01 19:09 ` Corey Minyard
2019-07-01 20:18 ` Steven Rostedt
2019-07-01 20:43 ` Corey Minyard
2019-07-01 21:06 ` Steven Rostedt
2019-07-01 21:13 ` Steven Rostedt
2019-07-01 21:28 ` Steven Rostedt
2019-07-01 21:34 ` Corey Minyard
2019-07-02 7:04 ` Kurt Kanzenbach
2019-07-02 8:35 ` Sebastian Andrzej Siewior
2019-07-02 11:40 ` Corey Minyard
2019-07-02 11:53 ` Sebastian Andrzej Siewior
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