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From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Byungchul Park <byungchul.park@lge.com>,
	jiangshanlai@gmail.com, josh@joshtriplett.org,
	mathieu.desnoyers@efficios.com, linux-kernel@vger.kernel.org,
	kernel-team@lge.com, peterz@infradead.org
Subject: Re: [PATCH] rcu: Report a quiescent state when it's exactly in the state
Date: Fri, 11 May 2018 10:27:35 -0700	[thread overview]
Message-ID: <20180511172735.GB26088@linux.vnet.ibm.com> (raw)
In-Reply-To: <20180511122712.2d67992b@gandalf.local.home>

On Fri, May 11, 2018 at 12:27:12PM -0400, Steven Rostedt wrote:
> On Fri, 11 May 2018 12:25:28 -0400
> Steven Rostedt <rostedt@goodmis.org> wrote:
> 
> > I would also say that one should never call schedule() directly without
> > changing its state to something other than TASK_RUNNING. Hence, calling
> > schedule directly is saying you are ready to sleep. But that is not the
> > case with cond_resched() which should always be called with the state
> > as TASK_RUNNING.
> 
> To continue this, with tracing, when a task is scheduled out in the
> RUNNING state, it is considered preempted, otherwise it is not.

I suppose another option would be for cond_resched_tasks_rcu_qs() to set
(and later clear) a per-CPU variable that causes rcu_note_context_switch()
to ignore its "preempt" parameter.  Byungchul's approach seems more
straightforward, though.

							Thanx, Paul

  reply	other threads:[~2018-05-11 17:26 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-11  8:30 [PATCH] rcu: Report a quiescent state when it's exactly in the state Byungchul Park
2018-05-11 12:57 ` Byungchul Park
2018-05-11 16:17   ` Paul E. McKenney
2018-05-11 16:23     ` Steven Rostedt
2018-05-11 16:25       ` Steven Rostedt
2018-05-11 16:27         ` Steven Rostedt
2018-05-11 17:27           ` Paul E. McKenney [this message]
2018-05-11 17:29             ` Steven Rostedt
2018-05-11 22:41     ` Joel Fernandes
2018-05-12  5:08       ` Paul E. McKenney
2018-05-12  6:30         ` Joel Fernandes
2018-05-12 14:41           ` Paul E. McKenney
2018-05-12 17:26             ` Steven Rostedt
2018-05-14  3:11               ` Byungchul Park
2018-05-13  0:09             ` Joel Fernandes
2018-05-14  2:59       ` Byungchul Park
2018-05-14 14:25         ` Byungchul Park
2018-05-14 21:04         ` Paul E. McKenney
2018-05-15  0:18           ` Byungchul Park

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