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Date:   Wed, 13 Sep 2023 11:03:30 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     mingo@kernel.org, vincent.guittot@linaro.org,
        linux-kernel@vger.kernel.org, juri.lelli@redhat.com,
        dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com,
        mgorman@suse.de, bristot@redhat.com, corbet@lwn.net,
        qyousef@layalina.io, chris.hyser@oracle.com,
        patrick.bellasi@matbug.net, pjt@google.com, pavel@ucw.cz,
        qperret@google.com, tim.c.chen@linux.intel.com, joshdon@google.com,
        timj@gnu.org, kprateek.nayak@amd.com, yu.c.chen@intel.com,
        youssefesmat@chromium.org, joel@joelfernandes.org, efault@gmx.de,
        tglx@linutronix.de
Subject: Re: [PATCH 07/15] sched/smp: Use lag to simplify cross-runqueue
 placement
Message-ID: <20230913090330.GC692@noisy.programming.kicks-ass.net>
References: <20230531115839.089944915@infradead.org>
 <20230531124604.068911180@infradead.org>
 <20230912153221.lSL8YgJJ@linutronix.de>
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On Tue, Sep 12, 2023 at 05:32:21PM +0200, Sebastian Andrzej Siewior wrote:
> On 2023-05-31 13:58:46 [+0200], Peter Zijlstra wrote:
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -12492,22 +12440,9 @@ static void task_fork_fair(struct task_s
> >  
> >  	cfs_rq = task_cfs_rq(current);
> >  	curr = cfs_rq->curr;
> > -	if (curr) {
> > +	if (curr)
> >  		update_curr(cfs_rq);
> > -		se->vruntime = curr->vruntime;
> > -	}
> >  	place_entity(cfs_rq, se, 1);
> > -
> > -	if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) {
> 
> Since the removal of sysctl_sched_child_runs_first there is no user of
> this anymore. There is still the sysctl file sched_child_runs_first with
> no functionality.
> Is this intended or should it be removed?

Hurmph... I think that knob has been somewat dysfunctional for a long
while and it might be time to remove it.

Ingo?