linux-kernel - Re: [patch v8 8/9] sched: consider runnable load average in move

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Date:	Mon, 17 Jun 2013 03:58:32 -0700
From:	Paul Turner <pjt@...gle.com>
To:	Alex Shi <alex.shi@...el.com>
Cc:	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Borislav Petkov <bp@...en8.de>,
	Namhyung Kim <namhyung@...nel.org>,
	Mike Galbraith <efault@....de>,
	Morten Rasmussen <morten.rasmussen@....com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...hat.com>,
	Michael Wang <wangyun@...ux.vnet.ibm.com>,
	Jason Low <jason.low2@...com>,
	Changlong Xie <changlongx.xie@...el.com>, sgruszka@...hat.com,
	Frédéric Weisbecker <fweisbec@...il.com>
Subject: Re: [patch v8 8/9] sched: consider runnable load average in move_tasks

On Fri, Jun 7, 2013 at 12:20 AM, Alex Shi <alex.shi@...el.com> wrote:
> Except using runnable load average in background, move_tasks is also
> the key functions in load balance. We need consider the runnable load
> average in it in order to the apple to apple load comparison.
>
> Morten had caught a div u64 bug on ARM, thanks!
>
> Signed-off-by: Alex Shi <alex.shi@...el.com>
> ---
>  kernel/sched/fair.c | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index eadd2e7..3aa1dc0 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -4178,11 +4178,14 @@ static int tg_load_down(struct task_group *tg, void *data)
>         long cpu = (long)data;
>
>         if (!tg->parent) {
> -               load = cpu_rq(cpu)->load.weight;
> +               load = cpu_rq(cpu)->avg.load_avg_contrib;
>         } else {
> +               unsigned long tmp_rla;
> +               tmp_rla = tg->parent->cfs_rq[cpu]->runnable_load_avg + 1;
> +
>                 load = tg->parent->cfs_rq[cpu]->h_load;
> -               load *= tg->se[cpu]->load.weight;
> -               load /= tg->parent->cfs_rq[cpu]->load.weight + 1;
> +               load *= tg->se[cpu]->avg.load_avg_contrib;
> +               load /= tmp_rla;

Why do we need the temporary here?

>         }
>
>         tg->cfs_rq[cpu]->h_load = load;
> @@ -4208,12 +4211,9 @@ static void update_h_load(long cpu)
>  static unsigned long task_h_load(struct task_struct *p)
>  {
>         struct cfs_rq *cfs_rq = task_cfs_rq(p);
> -       unsigned long load;
> -
> -       load = p->se.load.weight;
> -       load = div_u64(load * cfs_rq->h_load, cfs_rq->load.weight + 1);
>
> -       return load;
> +       return div64_ul(p->se.avg.load_avg_contrib * cfs_rq->h_load,
> +                       cfs_rq->runnable_load_avg + 1);
>  }
>  #else
>  static inline void update_blocked_averages(int cpu)
> --
> 1.7.12
>
--
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