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From: Peter Zijlstra <peterz@infradead.org>
To: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Yuyang Du <yuyang.du@intel.com>,
	mingo@kernel.org, linux-kernel@vger.kernel.org,
	bsegall@google.com, pjt@google.com, morten.rasmussen@arm.com,
	vincent.guittot@linaro.org, dietmar.eggemann@arm.com
Subject: Re: [PATCH v5 1/5] sched/fair: Clean up attach_entity_load_avg()
Date: Tue, 14 Jun 2016 14:11:33 +0200	[thread overview]
Message-ID: <20160614121133.GF30921@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20160614111152.GG2658@codeblueprint.co.uk>

On Tue, Jun 14, 2016 at 12:11:52PM +0100, Matt Fleming wrote:
> On Thu, 09 Jun, at 07:15:50AM, 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@intel.com>
> > ---
> >  kernel/sched/fair.c |   43 ++++++++++++++++++++-----------------------
> >  1 file changed, 20 insertions(+), 23 deletions(-)
>  
> Looks OK to me and makes the code easier to understand. Chasing
> ->avg.last_update_time values is tricky at the best of times.
> 
> Reviewed-by: Matt Fleming <matt@codeblueprint.co.uk>

So I still wonder at the point of this patch, since the next patch
deletes this code entirely. What's the point of cleaning it up if the
next patch removes it out-right.

  reply	other threads:[~2016-06-14 12:11 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-08 23:15 [PATCH v5 0/5] sched/fair: Fix attach and detach sched avgs for task group change and sched class change Yuyang Du
2016-06-08 23:15 ` [PATCH v5 1/5] sched/fair: Clean up attach_entity_load_avg() Yuyang Du
2016-06-14 11:11   ` Matt Fleming
2016-06-14 12:11     ` Peter Zijlstra [this message]
2016-06-14 22:18     ` Yuyang Du
2016-06-08 23:15 ` [PATCH v5 2/5] sched/fair: Fix attaching task sched avgs twice when switching to fair or changing task group Yuyang Du
2016-06-08 23:15 ` [PATCH v5 3/5] sched/fair: Move load and util avgs from wake_up_new_task() to sched_fork() Yuyang Du
2016-06-08 23:15 ` [PATCH v5 4/5] sched/fair: Skip detach sched avgs for new task when changing task groups Yuyang Du
2016-06-14 11:38   ` Matt Fleming
2016-06-14 14:36   ` Peter Zijlstra
2016-06-14 14:45     ` Peter Zijlstra
2016-06-08 23:15 ` [PATCH v5 5/5] sched/fair: Add inline to detach_entity_load_evg() Yuyang Du

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