linux-kernel - Re: [PATCH v4 1/5] sched/fair: Clean up attach_entity_load

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Date:	Mon, 6 Jun 2016 14:30:45 +0100
From:	Matt Fleming <matt@...eblueprint.co.uk>
To:	Yuyang Du <yuyang.du@...el.com>
Cc:	peterz@...radead.org, mingo@...nel.org,
	linux-kernel@...r.kernel.org, bsegall@...gle.com, pjt@...gle.com,
	morten.rasmussen@....com, vincent.guittot@...aro.org,
	dietmar.eggemann@....com
Subject: Re: [PATCH v4 1/5] sched/fair: Clean up attach_entity_load_avg()

On Mon, 06 Jun, at 08:20:37AM, Yuyang Du wrote:
> attach_entity_load_avg() is called (indirectly) from:
> 
>  - switched_to_fair(): switch between classes to fair
>  - task_move_group_fair(): move between task groups
>  - enqueue_entity_load_avg(): enqueue entity
> 
> Only in switched_to_fair() is it possible that the task's last_update_time
> is not 0 and therefore the task needs sched avgs update, so move the task
> sched avgs update to switched_to_fair() only. In addition, the code is
> refactored and code comments are updated.
> 
> No functionality change.
> 
> Signed-off-by: Yuyang Du <yuyang.du@...el.com>
> ---
>  kernel/sched/fair.c |   43 ++++++++++++++++++++-----------------------
>  1 file changed, 20 insertions(+), 23 deletions(-)

What about when tasks are moved between groups on CONFIG_SMP=n ?
Doesn't this change fail to age the load in that case?