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    SubjectRe: [PATCH 00/14] Modularize schedutil
    On Tue, May 12, 2020 at 5:11 PM Quentin Perret <qperret@google.com> wrote:
    >
    > On Tuesday 12 May 2020 at 16:08:56 (+0200), Rafael J. Wysocki wrote:
    > > 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?
    >
    > Sure thing, sorry if that wasn't clear.

    No worries.

    > The end goal with GKI is the following: Google will release a single
    > binary kernel image (signed, etc etc) that all devices using a given
    > Android version will be required to use. That image is however going to
    > be only for the core of the kernel (no drivers or anything of the sort).
    > Vendors and OEMs, on their end, will be responsible to build and ship
    > GKI-compatible modules for their respective devices. So, Android devices
    > will eventually ship with a Google-issued GKI, plus a bunch of
    > vendor-provided modules loaded during boot.

    If that is the case, then I absolutely think that schedutil should be
    part of the GKI.

    Moreover, that would have been my opinion even if it had been modular
    in the first place.

    > This is a significant shift from the current model where vendors
    > completely own the kernel, and are largely free to use the kernel config
    > they want. Today, those who don't use schedutil are free to turn the
    > config off, for example.

    So why is this regarded as a good thing?

    > But GKI changes that. The 'core' GKI config is effectively imposed to
    > the entire ecosystem. As of now, because it is 'bool' we have no choice
    > but to compile schedutil in the core GKI as some (most) partners use it.
    > But as you can imagine, that is not the preferred option of those who
    > _don't_ use schedutil.

    OTOH, it may as well be an incentive for them to switch over and
    report problems with it that they see.

    I absolutely would like to make schedutil the clearly preferred option
    and IMO avoiding to use it, especially for non-technical reasons,
    should be clearly less attractive.

    > Modularizing avoids any potential friction since
    > the vendors who want to use it will be able load the module, and the
    > others will simply not. That really is the reason for that series.

    If the long-term target is for everyone to use schedutil, then I don't
    quite see why making it easy to not include it in one's system is
    going to help.

    > Then there is an important question: why should upstream care about all
    > that stuff? That's obviously debatable, but my biased opinion is that
    > GKI is a good thing(TM). It's our opportunity to put some order in the
    > android ecosystem and to reduce the delta with mainline. That'll
    > definitely take time, and there will be Android-specific churn in GKI in
    > the beginning, but we'd like to keep that as small as possible, and to
    > converge to 0 looking forwards.

    That's a good goal, but I'm not sure if the least resistance path to
    it is the right one. :-)

    Cheers!

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