linux-kernel - Re: [PATCH 1/4] PM / devfreq: Track overall load monitor state instead of 'stop

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Date:   Thu, 14 Feb 2019 08:59:47 -0800
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Chanwoo Choi <cwchoi00@...il.com>
Cc:     MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Linux PM list <linux-pm@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-tegra@...r.kernel.org,
        Lukasz Luba <l.luba@...tner.samsung.com>
Subject: Re: [PATCH 1/4] PM / devfreq: Track overall load monitor state
 instead of 'stop_polling'

Hi Chanwoo,

On Thu, Feb 14, 2019 at 11:25:52PM +0900, Chanwoo Choi wrote:
> Hi Matthias,
> 
> 2019년 2월 14일 (목) 오후 7:16, Matthias Kaehlcke <mka@...omium.org>님이 작성:
> >
> > The field ->stop_polling indicates whether load monitoring should be/is
> > stopped, it is set in devfreq_monitor_suspend(). Change the variable to
> > hold the general state of load monitoring (stopped, running, suspended).
> > Besides improving readability of conditions involving the field and this
> > prepares the terrain for moving some duplicated code from the governors
> > into the devfreq core.
> >
> > Hold the devfreq lock in devfreq_monitor_start/stop() to ensure proper
> > synchronization.
> 
> IMHO, I'm not sure that there are any benefits changing
> from 'stop_polling' to 'monitor_state'. I have no objections
> if Myungjoo confirms it.

I agree that as an isolated change there isn't a clear benefit.
However in the context of the series the change is needed to
avoid resuming a load monitor that wasn't even started.

In case this series isn't accepted I'd still suggest to change the
name from 'stop_polling' to 'suspended'. I read 'stop_polling' as a
call for action, while 'suspended' is a state. IMO at least in some
contexts conditions using a state is clearer.

Cheers

Matthias