linux-kernel - Re: [PATCH 2/4] sched: cpufreq: Keep track of cpufreq utilization update flags

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Message-ID: <20171219032647.GO19815@vireshk-i7>
Date:   Tue, 19 Dec 2017 08:56:47 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Joel Fernandes <joelaf@...gle.com>
Cc:     Patrick Bellasi <patrick.bellasi@....com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Morten Rasmussen <morten.rasmussen@....com>,
        Juri Lelli <juri.lelli@...hat.com>,
        Todd Kjos <tkjos@...roid.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/4] sched: cpufreq: Keep track of cpufreq utilization
 update flags

On 19-12-17, 08:52, Viresh Kumar wrote:
> On 18-12-17, 19:18, Joel Fernandes wrote:
> > Hi Viresh,
> > 
> > On Mon, Dec 18, 2017 at 7:12 PM, Viresh Kumar <viresh.kumar@...aro.org> wrote:
> > > On 18-12-17, 12:14, Patrick Bellasi wrote:
> > >> For example, swithing from:
> > >>
> > >>  - void (*func)(struct update_util_data *data, u64 time,
> > >>  -              unsigned int flags))
> > >>  + void (*func)(struct update_util_data *data, u64 time,
> > >>  +              unsigned int flags, bool set))
> > >>
> > >> Where the additional boolean is actually used to define which
> > >> operation we wanna perform on the flags?
> > >
> > > The code will eventually have the same complexity or ugliness in both
> > > the cases. I would like to start with another flag for now and see if
> > > people prefer another parameter.
> > 
> > Though I think that will solve Rafael's concern of polluting the flags
> > for something schedutil specific. I also feel adding extra callback
> > parameter is cleaner than 2 new clear flags.
> 
> Okay, I will then wait for Rafael to come online and comment on what
> he would prefer before posting.

I thought about it once more. If we decide eventually to add another
parameter, then why isn't the approach that this patch takes better
than that? i.e. Use the 31st bit of flags for clear bit ? We can
remove setting/clearing flags for CFS, that's it.

-- 
viresh