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From: Peter Zijlstra <peterz@infradead.org>
To: Yuyang Du <yuyang.du@intel.com>
Cc: 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,
	matt@codeblueprint.co.uk
Subject: Re: [PATCH v5 4/5] sched/fair: Skip detach sched avgs for new task when changing task groups
Date: Tue, 14 Jun 2016 16:45:53 +0200	[thread overview]
Message-ID: <20160614144553.GA7381@worktop> (raw)
In-Reply-To: <20160614143649.GC3704@worktop>

On Tue, Jun 14, 2016 at 04:36:49PM +0200, Peter Zijlstra wrote:
> On Thu, Jun 09, 2016 at 07:15:53AM +0800, Yuyang Du wrote:
> > Newly forked task has not been enqueued, so should not be removed from
> > cfs_rq in task_move_group_fair(). To do so, we identify newly forked
> > tasks by their sched_avg's last_update_time in detach_entity_load_avg().
> 
> >  static void detach_entity_load_avg(struct cfs_rq *cfs_rq, struct sched_entity *se)
> >  {
> > +	/* Newly forked tasks are not attached yet. */
> > +	if (!se->avg.last_update_time)
> > +		return;
> 
> Urgh, so this results in two different heuristics to detect 'new' tasks
> and gives two different meanings to !last_update_time.
> 
> How about you use the existing heuristic as per vruntime_normalized()
> and do:
> 
> 	if (!se->sum_exec_runtime)
> 		return;

Hurm,. I see we already have this confusion as per
remove_entity_load_avg(). Could we fix it there too?

  reply	other threads:[~2016-06-14 14:46 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
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 [this message]
2016-06-08 23:15 ` [PATCH v5 5/5] sched/fair: Add inline to detach_entity_load_evg() Yuyang Du

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