Re: [PATCH 00/14] Modularize schedutil

[Viresh Kumar]

On 07-05-20, 19:09, Quentin Perret wrote:
> Android is trying very hard to use a single kernel image (commonly
> called Generic Kernel Image, or GKI), closely aligned with mainline, to
> run on all Android devices regardless of the vendor.
> 
> The GKI project intends to not only improve the status quo for Android
> users directly (less fragmentation simplifies updatability), but also
> to benefit upstream by forcing all vendors to agree on one common
> kernel, that we push hard to be aligned with mainline.
> 
> 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.
> 
> Indeed, in practice, Android devices often ship with only one CPUFreq
> governor enabled, and don't require any other that would simply waste
> memory for no benefits. All CPUFreq governors can already be built as
> modules with one notable exception: schedutil. Though popular in
> Android, some devices do not use schedutil, which is why it would be
> preferable to not have it unconditionally built in GKI. This series is
> an attempt to solve this problem, by making schedutil tristate.
> 
> While modularization is usually not something we want to see near the
> scheduler, it appeared to me as I wrote those patches that the
> particular case of schedutil was actually not too bad to implement.
> We already have to support switching governors at run-time, simply
> because userspace is free to do that, so the infrastructure for turning
> sugov on and off dynamically is already there. Loading the code a little
> later doesn't seem to make that a lot worse.
> 
> Patches 01-05 refactor some code to break the few dependencies on
> schedutil being builtin (notably EAS). Patches 06-12 export various
> symbols that schedutil needs when compiled as a module. And finally,
> patches 13-14 finish off the work by making the Kconfig tristate.

IMHO, you have over-broken the patches, like first two could be merged
together and all exports could have been done in a single patch, etc.
i.e. all related or similar changes together...

Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>

-- 
viresh