Re: [RFC PATCH] mm, thp: make deferred_split_shrinker memcg-aware

[Michal Hocko]

On Thu 19-10-17 13:03:23, Neha Agarwal wrote:
> deferred_split_shrinker is NUMA aware. Making it memcg-aware if
> CONFIG_MEMCG is enabled to prevent shrinking memory of memcg(s) that are
> not under memory pressure. This change isolates memory pressure across
> memcgs from deferred_split_shrinker perspective, by not prematurely
> splitting huge pages for the memcg that is not under memory pressure.

Why do we need this? THP pages are usually not shared between memcgs. Or
do you have a real world example where this is not the case? Your patch
is adding quite a lot of (and to be really honest very ugly) code so
there better should be a _very_ good reason to justify it. I haven't
looked very closely to the code, at least all those ifdefs in the code
are too ugly to live.
-- 
Michal Hocko
SUSE Labs