linux-kernel - Re: [PATCH -next] sched/fair: Move update_nohz_stats() under CONFIG_NO_HZ

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Date:   Tue, 30 Mar 2021 14:22:01 +0200
From:   Vincent Guittot <vincent.guittot@...aro.org>
To:     Kefeng Wang <wangkefeng.wang@...wei.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Juri Lelli <juri.lelli@...hat.com>
Subject: Re: [PATCH -next] sched/fair: Move update_nohz_stats() under CONFIG_NO_HZ_COMMON

On Tue, 30 Mar 2021 at 14:06, Kefeng Wang <wangkefeng.wang@...wei.com> wrote:
>
> update_nohz_stats() only call _nohz_idle_balance() under CONFIG_NO_HZ_COMMON.

a similar patch has already been sent and reviewed :
20210329144029.29200-1-yuehaibing@...wei.com

>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
> ---
>  kernel/sched/fair.c | 40 ++++++++++++++++++----------------------
>  1 file changed, 18 insertions(+), 22 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 6d73bdbb2d40..2a20ada83cbb 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -8395,28 +8395,6 @@ group_type group_classify(unsigned int imbalance_pct,
>         return group_has_spare;
>  }
>
> -static bool update_nohz_stats(struct rq *rq)
> -{
> -#ifdef CONFIG_NO_HZ_COMMON
> -       unsigned int cpu = rq->cpu;
> -
> -       if (!rq->has_blocked_load)
> -               return false;
> -
> -       if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask))
> -               return false;
> -
> -       if (!time_after(jiffies, READ_ONCE(rq->last_blocked_load_update_tick)))
> -               return true;
> -
> -       update_blocked_averages(cpu);
> -
> -       return rq->has_blocked_load;
> -#else
> -       return false;
> -#endif
> -}
> -
>  /**
>   * update_sg_lb_stats - Update sched_group's statistics for load balancing.
>   * @env: The load balancing environment.
> @@ -10380,6 +10358,24 @@ void nohz_balance_enter_idle(int cpu)
>         WRITE_ONCE(nohz.has_blocked, 1);
>  }
>
> +static bool update_nohz_stats(struct rq *rq)
> +{
> +       unsigned int cpu = rq->cpu;
> +
> +       if (!rq->has_blocked_load)
> +               return false;
> +
> +       if (!cpumask_test_cpu(cpu, nohz.idle_cpus_mask))
> +               return false;
> +
> +       if (!time_after(jiffies, READ_ONCE(rq->last_blocked_load_update_tick)))
> +               return true;
> +
> +       update_blocked_averages(cpu);
> +
> +       return rq->has_blocked_load;
> +}
> +
>  /*
>   * Internal function that runs load balance for all idle cpus. The load balance
>   * can be a simple update of blocked load or a complete load balance with
> --
> 2.26.2
>