linux-kernel - Re: [PATCH 3/6] sched/fair: merge for each idle cpu loop of ILB

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Date:   Tue, 09 Feb 2021 13:09:34 +0000
From:   Valentin Schneider <valentin.schneider@....com>
To:     Vincent Guittot <vincent.guittot@...aro.org>, mingo@...hat.com,
        peterz@...radead.org, juri.lelli@...hat.com,
        dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
        mgorman@...e.de, fweisbec@...il.com, tglx@...utronix.de,
        bristot@...hat.com, linux-kernel@...r.kernel.org,
        joel@...lfernandes.org
Cc:     qais.yousef@....com, Vincent Guittot <vincent.guittot@...aro.org>
Subject: Re: [PATCH 3/6] sched/fair: merge for each idle cpu loop of ILB

On 05/02/21 12:48, Vincent Guittot wrote:
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 60b8c1c68ab9..c587af230010 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -10043,22 +10043,9 @@ static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle)
>        * When the cpu is attached to null domain for ex, it will not be
>        * updated.
>        */
> -	if (likely(update_next_balance)) {
> +	if (likely(update_next_balance))
>               rq->next_balance = next_balance;
>
> -#ifdef CONFIG_NO_HZ_COMMON
> -		/*
> -		 * If this CPU has been elected to perform the nohz idle
> -		 * balance. Other idle CPUs have already rebalanced with
> -		 * nohz_idle_balance() and nohz.next_balance has been
> -		 * updated accordingly. This CPU is now running the idle load
> -		 * balance for itself and we need to update the
> -		 * nohz.next_balance accordingly.
> -		 */
> -		if ((idle == CPU_IDLE) && time_after(nohz.next_balance, rq->next_balance))
> -			nohz.next_balance = rq->next_balance;
> -#endif
> -	}

I was never fond of this bit, so FWIW I'm happy to see it go!