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: Tue, 11 Apr 2017 17:39:00 -0400 [thread overview]
Message-ID: <20170411173900.00f4b6c6@gandalf.local.home> (raw)
In-Reply-To: <20170411173447.0bdb9f77@gandalf.local.home>
On Tue, 11 Apr 2017 17:34:47 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
> On Tue, 11 Apr 2017 17:31:33 -0400
> Steven Rostedt <rostedt@goodmis.org> wrote:
>
> > The thread gets created when I enable the benchmark tracepoint. It just
> > so happens that my test enables *all* tracepoints, which would of
> > course include this one as well.
> >
> > I'll have to look at this code to see why it is getting missed.
>
> Yep, this thread never goes to sleep, but will call cond_resched()
> periodically. This keeps rcu_tasks() from finishing.
>
> Should I add a direct "schedule()" in there instead of a
> cond_resched(), or do you think rcu_tasks should have cond_resched() be
> a quiescent state as well?
Actually, I believe this found a bug in my trace_event benchmark
thread. On a preempt kernel, cond_resched() is a nop and expects to
only be preempted. Calling schedule() directly should fix everything. I
shouldn't depend on cond_resched() here.
-- Steve
next prev parent reply other threads:[~2017-04-11 21:39 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 [this message]
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
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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