linux-kernel - Re: [PATCH v5 2/7] sched: remove SMP cover for runnable variables in cfs

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Message-ID: <CAPM31R+oBDRF4geM451-ySCtkU1NpqFT_R1mtB95jV-pnLBimQ@mail.gmail.com>
Date:	Mon, 6 May 2013 01:01:41 -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>
Subject: Re: [PATCH v5 2/7] sched: remove SMP cover for runnable variables in cfs_rq

On Sun, May 5, 2013 at 6:45 PM, Alex Shi <alex.shi@...el.com> wrote:
> The following variables were covered under CONFIG_SMP in struct cfs_rq.
> but similar runnable variables work for UP in struct rq and task_group.
> like rq->avg, task_group->load_avg.
> So move them out, they also can work with UP.

Is there a proposed use-case for UP?  My apologies if I missed it in
an alternate patch.

It would seem the only possibly useful thing there would the the
per-rq average for p-state selection; but we can get that without the
per-entity values already.

>
>          u64 runnable_load_avg, blocked_load_avg;
>          atomic64_t decay_counter, removed_load;
>          u64 last_decay;
>
>          u32 tg_runnable_contrib;
>          u64 tg_load_contrib;
>
> Signed-off-by: Alex Shi <alex.shi@...el.com>
> ---
>  kernel/sched/sched.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index 7f36024f..1a02b90 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -226,7 +226,6 @@ struct cfs_rq {
>         unsigned int nr_spread_over;
>  #endif
>
> -#ifdef CONFIG_SMP
>         /*
>          * CFS Load tracking
>          * Under CFS, load is tracked on a per-entity basis and aggregated up.
> @@ -242,6 +241,7 @@ struct cfs_rq {
>         u64 tg_load_contrib;
>  #endif /* CONFIG_FAIR_GROUP_SCHED */
>
> +#ifdef CONFIG_SMP
>         /*
>          *   h_load = weight * f(tg)
>          *
> --
> 1.7.12
>
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