linux-kernel - Re: [PATCH 7/7 v3] sched: fix wrong utilization accounting when switching to fair class

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Message-ID: <20160926145354.GL5020@twins.programming.kicks-ass.net>
Date:   Mon, 26 Sep 2016 16:53:54 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Vincent Guittot <vincent.guittot@...aro.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Yuyang Du <yuyang.du@...el.com>,
        Morten Rasmussen <Morten.Rasmussen@....com>,
        Linaro Kernel Mailman List <linaro-kernel@...ts.linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Paul Turner <pjt@...gle.com>,
        Benjamin Segall <bsegall@...gle.com>
Subject: Re: [PATCH 7/7 v3] sched: fix wrong utilization accounting when
 switching to fair class

On Thu, Sep 22, 2016 at 02:25:18PM +0200, Peter Zijlstra wrote:
> On Tue, Sep 20, 2016 at 03:06:04PM +0200, Vincent Guittot wrote:
> > > Also, even it things magically worked out, its still very icky to mix
> > > the normalized vruntime into things.
> > 
> > I agree
> 
> In any case, I pushed out a bunch of patches to:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/tmp
> 
> they appear to be able to build a kernel, but that's not much testing.

Hurmph, its buggered for cgroups. When we get the newidle lockbreak
between dequeue and put_prev_task, the load-balance pull can add a task
to the 'current' cgroup.

Which suggests we cannot do that enqueue_entity() optimization, unless
we fix that dequeue+put atomicy muck.