linux-kernel - Re: [tip: sched/core] sched,fair: skip newidle

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Message-ID: <YIEwnnhG9bFkPqQs@hirez.programming.kicks-ass.net>
Date:   Thu, 22 Apr 2021 10:15:26 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     linux-kernel@...r.kernel.org
Cc:     linux-tip-commits@...r.kernel.org, Rik van Riel <riel@...riel.com>,
        x86@...nel.org, Vincent Guittot <vincent.guittot@...aro.org>
Subject: Re: [tip: sched/core] sched,fair: skip newidle_balance if a wakeup
 is pending

On Thu, Apr 22, 2021 at 07:36:00AM -0000, tip-bot2 for Rik van Riel wrote:
> @@ -10684,7 +10693,12 @@ out:
>  	if (time_after(this_rq->next_balance, next_balance))
>  		this_rq->next_balance = next_balance;
>  
> -	if (pulled_task)
> +	/*
> +	 * If we are no longer idle, do not let the time spent here pull
> +	 * down this_rq->avg_idle. That could lead to newidle_balance not
> +	 * doing enough work, and the CPU actually going idle.
> +	 */
> +	if (pulled_task || this_rq->ttwu_pending)
>  		this_rq->idle_stamp = 0;

I've un-committed this patch, because vingu was reporting increased idle
time because of this hunk.  I had mistakenly assumed that was sorted
with v3, sorry for not keeping better track of things.

(also, now that I look again, please also fix the Subject to have a
capital after the :)