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Date:   Fri, 8 May 2020 13:26:09 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     Quentin Perret <qperret@google.com>, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com,
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        vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
        rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
        mcgrof@kernel.org, keescook@chromium.org, yzaikin@google.com,
        fweisbec@gmail.com, tkjos@google.com, kernel-team@android.com
Subject: Re: [PATCH 00/14] Modularize schedutil
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 <20200508103721.GA3860390@kroah.com>
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On Fri, May 08, 2020 at 12:37:21PM +0200, Greg KH wrote:
> On Fri, May 08, 2020 at 10:11:28AM +0200, Peter Zijlstra wrote:
> > On Thu, May 07, 2020 at 07:09:58PM +0100, Quentin Perret wrote:
> > > One challenge to implement GKI is to avoid bloating the kernel by
> > > compiling too many things in, especially given that different devices
> > > need different things. As such, anything that can be turned into a
> > > module helps GKI, by offering an alternative to having that component
> > > built-in. This is true for pretty much anything that can be made
> > > modular, including drivers as well as other kernel components, such as
> > > CPUFreq governors.
> > 
> > The idea is to move to 1 governor, schedutil. Also, I abhor all the
> > exports this thing does. Modules have no business touching most of that.
> > 
> > Look at every EXPORT you do and wonder ask yourself how you can abuse
> > it. Modules are not a good thing, they're horrible pieces of crap.
> 
> Quentin, what is missing from schedutil that warrants the need for a
> totally different governor?  Is there specific problems with the
> existing ones or is this just an instance of "we wrote our own a long
> time ago and never pushed it upstream" from various SoC companies?

At the very least there's that interactive governor that's really
popular with Android. But IIRC there's a whole scala of home-brew
governors and tweaks out there.

And instead of enabling that crap, we should be discouraging it.
Consolidate and kill the governor interface.