linux-kernel - Re: [PATCH] sched: Distinguish sched_wakeup event when wake up a task which did schedule out or not.

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Message-ID: <536C1E50.5020806@cn.fujitsu.com>
Date:	Fri, 9 May 2014 09:16:16 +0900
From:	Dongsheng Yang <yangds.fnst@...fujitsu.com>
To:	Dongsheng Yang <yangds.fnst@...fujitsu.com>
CC:	<rostedt@...dmis.org>, <peterz@...radead.org>,
	<bsegall@...gle.com>, <mingo@...hat.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] sched: Distinguish sched_wakeup event when wake up a
 task which did schedule out or not.

Hi steven, does this version look good to you?

Thanx :)

On 05/06/2014 10:52 AM, Dongsheng Yang wrote:
> ttwu_do_wakeup() is called when the task's state is switched back to
> TASK_RUNNING, whether or not the task actually scheduled out. Tracing
> the wakeup event when the task never scheduled out is quite confusing.
>
> This patch take the use of 'success' parameter in sched_wakeup tracepoint,
> to indicate that the task we are waking up did schedule out or just
> change its state to TASK_RUNNING.
>
> success is true:
> 	task was out of run queue and sleeping, we are really wake it up.
> success is false:
> 	taks was on run queue all the time and we just change its state
> 	to TASK_RUNNING.
>
> Signed-off-by: Dongsheng Yang <yangds.fnst@...fujitsu.com>
> ---
>   kernel/sched/core.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 9074c6d..14b9fe4 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -1420,6 +1420,7 @@ static void ttwu_activate(struct rq *rq, struct task_struct *p, int en_flags)
>   {
>   	activate_task(rq, p, en_flags);
>   	p->on_rq = 1;
> +	trace_sched_wakeup(p, true);
>   
>   	/* if a worker is waking up, notify workqueue */
>   	if (p->flags & PF_WQ_WORKER)
> @@ -1433,7 +1434,6 @@ static void
>   ttwu_do_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
>   {
>   	check_preempt_curr(rq, p, wake_flags);
> -	trace_sched_wakeup(p, true);
>   
>   	p->state = TASK_RUNNING;
>   #ifdef CONFIG_SMP
> @@ -1481,6 +1481,7 @@ static int ttwu_remote(struct task_struct *p, int wake_flags)
>   	if (p->on_rq) {
>   		/* check_preempt_curr() may use rq clock */
>   		update_rq_clock(rq);
> +		trace_sched_wakeup(p, false);
>   		ttwu_do_wakeup(rq, p, wake_flags);
>   		ret = 1;
>   	}
> @@ -1675,6 +1676,8 @@ static void try_to_wake_up_local(struct task_struct *p)
>   
>   	if (!p->on_rq)
>   		ttwu_activate(rq, p, ENQUEUE_WAKEUP);
> +	else
> +		trace_sched_wakeup(p, false);
>   
>   	ttwu_do_wakeup(rq, p, 0);
>   	ttwu_stat(p, smp_processor_id(), 0);

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