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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Tue, 12 May 2020 16:08:56 +0200
Message-ID: <CAJZ5v0hN708uvurZ-3oo90qUJFw3=Eg0OmtTaOKXQgNPXhCkFg@mail.gmail.com>
Subject: Re: [PATCH 00/14] Modularize schedutil
To:     Quentin Perret <qperret@google.com>
Cc:     "Rafael J. Wysocki" <rafael@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Greg KH <gregkh@linuxfoundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux PM <linux-pm@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Sudeep Holla <sudeep.holla@arm.com>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Benjamin Segall <bsegall@google.com>,
        Mel Gorman <mgorman@suse.de>,
        "Luis R. Rodriguez" <mcgrof@kernel.org>,
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On Tue, May 12, 2020 at 3:58 PM Quentin Perret <qperret@google.com> wrote:
>
> On Tuesday 12 May 2020 at 12:25:17 (+0200), Rafael J. Wysocki wrote:
> > Still, IMO it would be fair to say that if uclamps are used, schedutil
> > is very likely to be preferred.
> >
> > Kconfig can be made select schedutil when enabling uclamps or similar
> > to express that preference.
>
> Right, fair enough. Making schedutil default to y when uclamp is
> compiled in should do the trick (and avoid using 'select'). Would that
> work for you?

I think so.

> > What you are proposing is basically to add complexity and the reason
> > for doing that seems to be convenience (and that's not the users'
> > convenience for that matter) which is not really super-convincing.
>
> Forcing our users to build in their products something they don't want
> to use tends to be a very real problem for what we're trying to achieve,
> so it's certainly not just convenience from our perspective. I can
> understand that yours might be different, though.

I would like to understand the nature of the problem here.

If some piece of kernel code is modular, it still needs to be build.
The difference is when and how it gets loaded, so can you possibly
elaborate here?

Cheers!