Re: [PATCH 2/2] zsmalloc: fine-grained inuse ratio based fullness grouping

[Yosry Ahmed <yosryahmed@google.com>]

On Thu, Feb 9, 2023 at 8:30 PM Sergey Senozhatsky
<senozhatsky@chromium.org> wrote:
>
> On (23/02/09 20:25), Yosry Ahmed wrote:
> > > On (23/02/07 10:47), Sergey Senozhatsky wrote:
> [..]
> > > Forgot to mention, I was also thinking about extending zsmalloc stats
> > > file and providing values for each fullness group per class, as opposed
> > > to current ALMOST_EMPTY and ALMOST_FULL stats, which don't tell much.
> >
> > Makes sense.
> >
> > >
> > > I can get rid of static const arrays and pass "begin / end" group IDs to
> > > functions that iterate fullness lists and pick the first head page, but
> > > I think that enum values will stay.
> >
> > Do they have to stay for a technical reason or just to make reviews simpler?
>
> We need to be able to do zs_stat_get(class, CLASS_USAGE_70) or
> zs_stat_get(class, CLASS_USAGE_10) in zs_stats_size_show() to
> show class's fullness stats.

If we use #define FULLNESS_GROUPS 10 for example, we can break down
struct zs_size_stat from a single array to two arrays, one of the for
fullness groups and the other one for the rest of the stats (e.g.
OBJ_USED). We can have different helpers to update each, the former
taking in a fullness value (0 to FULLNESS_GROUPS-1), and the latter an
enum. WDYT?