linux-kernel - Re: [PATCH 2/2] sched: Distangle worker accounting from rq lock

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Date:   Tue, 9 Apr 2019 10:22:50 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Tejun Heo <tj@...nel.org>
Cc:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        linux-kernel@...r.kernel.org,
        Lai Jiangshan <jiangshanlai@...il.com>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Daniel Bristot de Oliveira <bristot@...hat.com>
Subject: Re: [PATCH 2/2] sched: Distangle worker accounting from rq lock

On Mon, Apr 08, 2019 at 12:45:05PM -0700, Tejun Heo wrote:
> Hello,
> 
> On Wed, Mar 13, 2019 at 05:55:48PM +0100, Sebastian Andrzej Siewior wrote:
> > From: Thomas Gleixner <tglx@...utronix.de>
> > 
> > The worker accounting for CPU bound workers is plugged into the core
> > scheduler code and the wakeup code. This is not a hard requirement and
> > can be avoided by keeping track of the state in the workqueue code
> > itself.
> > 
> > Keep track of the sleeping state in the worker itself and call the
> > notifier before entering the core scheduler. There might be false
> > positives when the task is woken between that call and actually
> > scheduling, but that's not really different from scheduling and being
> > woken immediately after switching away. When nr_running is updated when
> > the task is retunrning from schedule() then it is later compared when it
> > is done from ttwu().
> > 
> > Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> > Cc: Daniel Bristot de Oliveira <bristot@...hat.com>
> > Link: http://lkml.kernel.org/r/20110622174919.135236139@linutronix.de
> > Link: http://lkml.kernel.org/r/ad2b29b5715f970bffc1a7026cabd6ff0b24076a.1532952814.git.bristot@redhat.com
> > Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> > [bigeasy: preempt_disable() around wq_worker_sleeping() by Daniel Bristot de
> >           Oliveira]
> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
> 
> This looks good from wq side.  Peter, are you okay with routing this
> through the wq tree?  If you wanna take it through the sched tree,
> please feel free to add
> 
> Acked-by: Tejun Heo <tj@...nel.org>

If you don't mind I'll take it through the sched tree, because while
looking at it I did a few cleanups on top.

Thanks!