From: Steven Rostedt <rostedt@goodmis.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: There is a Tasks RCU stall warning
Date: Wed, 12 Apr 2017 10:59:37 -0400 [thread overview]
Message-ID: <20170412105937.43175471@gandalf.local.home> (raw)
In-Reply-To: <20170412144800.GA12365@linux.vnet.ibm.com>
On Wed, 12 Apr 2017 07:48:00 -0700
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote:
> > > > Like this? (Untested, but builds at least some of the time.)
> > >
> > > Not like that... :-/ Update on its way.
> >
> > Perhaps more like this. Started rcutorture on it, will see how it goes.
I just love the above discussion with yourself ;-)
>
> Do you need this patch? If so, I should do some more work on it to
> eliminate the extra common-case branch on the scheduler fastpath.
>
Do I still need this patch? Maybe. :-)
I changed my benchmark test to call cond_resched_rcu_qs() instead and
that appears to fix the issue. But I'm not sure if there's any other
kthread out there that just calls cond_resched() or schedule().
Actually, I think it is still a good idea to have it. I believe that it
will still allow synchronize_rcu_tasks() to progress even if there's a
kthread task that is constantly being woken up, and never sleeps when
it calls schedule(), as it may always have the R state.
-- Steve
next prev parent reply other threads:[~2017-04-12 14:59 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-11 21:18 There is a Tasks RCU stall warning Paul E. McKenney
2017-04-11 21:21 ` Steven Rostedt
2017-04-11 21:32 ` Paul E. McKenney
2017-04-11 21:31 ` Steven Rostedt
2017-04-11 21:34 ` Steven Rostedt
2017-04-11 21:39 ` Steven Rostedt
2017-04-11 21:44 ` Paul E. McKenney
2017-04-11 21:49 ` Steven Rostedt
2017-04-11 21:56 ` Paul E. McKenney
2017-04-11 22:15 ` Steven Rostedt
2017-04-11 23:01 ` Paul E. McKenney
2017-04-11 23:04 ` Paul E. McKenney
2017-04-11 23:11 ` Paul E. McKenney
2017-04-12 3:23 ` Paul E. McKenney
2017-04-12 13:18 ` Steven Rostedt
2017-04-12 14:19 ` Paul E. McKenney
2017-04-12 14:42 ` Steven Rostedt
2017-04-12 15:18 ` Paul E. McKenney
2017-04-12 15:53 ` Steven Rostedt
2017-04-12 16:26 ` Paul E. McKenney
2017-04-12 16:49 ` Steven Rostedt
2017-04-12 14:48 ` Paul E. McKenney
2017-04-12 14:59 ` Steven Rostedt [this message]
2017-04-12 16:27 ` Paul E. McKenney
2017-04-12 16:57 ` Steven Rostedt
2017-04-12 17:07 ` Paul E. McKenney
2017-04-12 17:13 ` Steven Rostedt
2017-04-12 20:02 ` Paul E. McKenney
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