Messages in this thread | | | Date | Fri, 13 Oct 2023 16:17:21 +0200 | From | Michal Hocko <> | Subject | Re: [PATCH] mm: memcontrol: Don't css_get() on root_mem_cgroup in get_mem_cgroup_from_mm() |
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On Thu 12-10-23 12:15:04, Waiman Long wrote: > As reference counting in the root memcg is disabled, there is no need > to get a reference if root memcg is to be returned.
Does this give any measurable wins?
> Signed-off-by: Waiman Long <longman@redhat.com> > --- > mm/memcontrol.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 5b009b233ab8..2b3864194042 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1060,8 +1060,10 @@ struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm) > rcu_read_lock(); > do { > memcg = mem_cgroup_from_task(rcu_dereference(mm->owner)); > - if (unlikely(!memcg)) > + if (unlikely(!memcg)) { > memcg = root_mem_cgroup; > + break; > + } > } while (!css_tryget(&memcg->css)); > rcu_read_unlock(); > return memcg; > -- > 2.39.3
-- Michal Hocko SUSE Labs
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