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@xxxxxxxxxx>
> ---
> 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
