| Message ID | 20231012161504.3445042-1-longman@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: memcontrol: Don't css_get() on root_mem_cgroup in get_mem_cgroup_from_mm() | expand |
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
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;
As reference counting in the root memcg is disabled, there is no need to get a reference if root memcg is to be returned. Signed-off-by: Waiman Long <longman@redhat.com> --- mm/memcontrol.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)