On Tue 14-08-18 17:36:20, Roman Gushchin wrote: > Memcg charge is batched using per-cpu stocks, so an offline memcg > can be pinned by a cached charge up to a moment, when a process > belonging to some other cgroup will charge some memory on the same > cpu. In other words, cached charges can prevent a memory cgroup > from being reclaimed for some time, without any clear need. > > Let's optimize it by explicit draining of all stocks on css offlining. > As draining is performed asynchronously, and is skipped if any > parallel draining is happening, it's cheap. Yes this makes sense. > Signed-off-by: Roman Gushchin <guro@xxxxxx> > Cc: Johannes Weiner <hannes@xxxxxxxxxxx> > Cc: Michal Hocko <mhocko@xxxxxxxxxx> > Cc: Konstantin Khlebnikov <koct9i@xxxxxxxxx> > Cc: Tejun Heo <tj@xxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> > --- > mm/memcontrol.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 4e3c1315b1de..cfb64b5b9957 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -4575,6 +4575,8 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) > memcg_offline_kmem(memcg); > wb_memcg_offline(memcg); > > + drain_all_stock(memcg); > + > mem_cgroup_id_put(memcg); > } > > -- > 2.14.4 -- Michal Hocko SUSE Labs
