From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1754316AbcFTJwf (ORCPT <rfc822;w@1wt.eu>);
	Mon, 20 Jun 2016 05:52:35 -0400
Received: from merlin.infradead.org ([205.233.59.134]:43019 "EHLO
	merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1753881AbcFTJwY (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Mon, 20 Jun 2016 05:52:24 -0400
Date: Mon, 20 Jun 2016 11:52:14 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Yuyang Du <yuyang.du@intel.com>, Ingo Molnar <mingo@kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Mike Galbraith <umgwanakikbuti@gmail.com>,
        Benjamin Segall <bsegall@google.com>, Paul Turner <pjt@google.com>,
        Morten Rasmussen <morten.rasmussen@arm.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Matt Fleming <matt@codeblueprint.co.uk>
Subject: Re: [PATCH 4/4] sched,fair: Fix PELT integrity for new tasks
Message-ID: <20160620095214.GF30154@twins.programming.kicks-ass.net>
References: <20160617120136.064100812@infradead.org>
 <20160617120454.150630859@infradead.org>
 <CAKfTPtAUtteP0V5-1u2n0YFDdFbZfwSqigHjOfM32Vbw3iAPbg@mail.gmail.com>
 <20160617142814.GT30154@twins.programming.kicks-ass.net>
 <20160617160239.GL30927@twins.programming.kicks-ass.net>
 <20160617161831.GM30927@twins.programming.kicks-ass.net>
 <20160620092339.GA4526@vingu-laptop>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20160620092339.GA4526@vingu-laptop>
User-Agent: Mutt/1.5.23.1 (2014-03-12)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Mon, Jun 20, 2016 at 11:23:39AM +0200, Vincent Guittot wrote:

> > @@ -738,7 +739,20 @@ void post_init_entity_util_avg(struct sc
> >  		sa->util_sum = sa->util_avg * LOAD_AVG_MAX;
> >  	}
> >  
> > -	update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq, false);
> > +	if (entity_is_task(se)) {
> 
> Why only task ?

Only tasks can be of another class, the cgroup se's must be fair.

> > +		struct task_struct *p = task_of(se);
> > +		if (p->sched_class != &fair_sched_class) {
> > +			/*
> > +			 * For !fair tasks do attach_entity_load_avg()
> > +			 * followed by detach_entity_load_avg() as per
> > +			 * switched_from_fair().
> > +			 */
> > +			se->avg.last_update_time = now;
> > +			return;
> > +		}
> > +	}
> > +
> > +	update_cfs_rq_load_avg(now, cfs_rq, false);
> >  	attach_entity_load_avg(cfs_rq, se);
> 
> Don't we have to do a complete attach with attach_task_cfs_rq instead
> of just the load_avg ? to set also depth ?

init_tg_cfs_entity() sets depth for cgroup entities,
attach_task_cfs_rq() reset depth on switched_to().

So that should be fine.

> ---
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -723,6 +723,7 @@ void post_init_entity_util_avg(struct sched_entity *se)
>  	struct cfs_rq *cfs_rq = cfs_rq_of(se);
>  	struct sched_avg *sa = &se->avg;
>  	long cap = (long)(SCHED_CAPACITY_SCALE - cfs_rq->avg.util_avg) / 2;
> +	u64 now = cfs_rq_clock_task(cfs_rq);
>  
>  	if (cap > 0) {
>  		if (cfs_rq->avg.util_avg != 0) {
> @@ -737,8 +738,18 @@ void post_init_entity_util_avg(struct sched_entity *se)
>  		sa->util_sum = sa->util_avg * LOAD_AVG_MAX;
>  	}
>  
> -	update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq, false);
> -	attach_entity_load_avg(cfs_rq, se);

There is no p here...

> +	if (p->sched_class == &fair_sched_class) {
> +		/* fair entity must be attached to cfs_rq */
> +		attach_task_cfs_rq(se);
> +	} else {
> +		/*
> +		 * For !fair tasks do attach_entity_load_avg()
> +		 * followed by detach_entity_load_avg() as per
> +		 * switched_from_fair().
> +		 */
> +		se->avg.last_update_time = now;
> +	}
> +
>  }

And you're now not attaching new cgroup thingies.