Re: [PATCH 0/3] mm: add per-migratetype counts to buddy allocator and optimize pagetypeinfo access

[Hongru Zhang]

> > Despite the above challenges, Android device manufacturers hope to ensure
> > a good user experience (no UI jank) across all situations.
> >
> > Even at 60 Hz frame refresh rate (90 Hz, 120 Hz also supported now), all
> > work from user input to render and display should be done within 16.7 ms.
> > To achieve this goal, the management components perform tasks such as:
> > - Track system resource status: what system has
> >   (system resource awareness)
> > - Learn and predict app resource demands: what app needs
> >   (resource demand awareness)
> > - Monitor app launch, exit, and foreground-background switches: least
> >   important app gives back resource to system to serve most important
> >   one, usually the foreground app
> >   (user intent awareness)
> >
> > Tracking system resources seems necessary for Android devices, not
> > optional. So the related paths are not that cold on Android devices.
>
> These are all good background information. But how does userspace monitor
> utilize pageblock migratetype information? Can you give a concrete example?
>
> Something like when free_movable is low, background apps is killed to
> provide more free pages? Or is userspace monitor even trying to attribute
> different pageblock usage to each app by monitoring /proc/pagetypeinfo
> before and after an app launch?
>
> Thanks.

AOSP:
https://android.googlesource.com/platform/frameworks/base/+/refs/heads/main/core/java/com/android/internal/app/procstats/ProcessStats.java#:~:text=public%20void%20updateFragmentation()

We have proprietary algorithms, but they are confidential. I cannot
describe them publicly, sorry about that.