* [patch] mm: memcontrol: micro-optimize mem_cgroup_update_page_stat()
@ 2014-10-20 15:17 Johannes Weiner
2014-10-20 18:59 ` Michal Hocko
0 siblings, 1 reply; 2+ messages in thread
From: Johannes Weiner @ 2014-10-20 15:17 UTC (permalink / raw)
To: Andrew Morton
Cc: Michal Hocko, Vladimir Davydov, linux-mm, cgroups, linux-kernel
Do not look up the page_cgroup when the memory controller is
runtime-disabled, but do assert that the locking protocol is followed
under DEBUG_VM regardless. Also remove the unused flags variable.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
mm/memcontrol.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 76892eb89d26..bea3fddb3372 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2177,13 +2177,14 @@ void mem_cgroup_update_page_stat(struct page *page,
enum mem_cgroup_stat_index idx, int val)
{
struct mem_cgroup *memcg;
- struct page_cgroup *pc = lookup_page_cgroup(page);
- unsigned long uninitialized_var(flags);
+ struct page_cgroup *pc;
+
+ VM_BUG_ON(!rcu_read_lock_held());
if (mem_cgroup_disabled())
return;
- VM_BUG_ON(!rcu_read_lock_held());
+ pc = lookup_page_cgroup(page);
memcg = pc->mem_cgroup;
if (unlikely(!memcg || !PageCgroupUsed(pc)))
return;
--
2.1.2
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [patch] mm: memcontrol: micro-optimize mem_cgroup_update_page_stat()
2014-10-20 15:17 [patch] mm: memcontrol: micro-optimize mem_cgroup_update_page_stat() Johannes Weiner
@ 2014-10-20 18:59 ` Michal Hocko
0 siblings, 0 replies; 2+ messages in thread
From: Michal Hocko @ 2014-10-20 18:59 UTC (permalink / raw)
To: Johannes Weiner
Cc: Andrew Morton, Vladimir Davydov, linux-mm, cgroups, linux-kernel
On Mon 20-10-14 11:17:39, Johannes Weiner wrote:
> Do not look up the page_cgroup when the memory controller is
> runtime-disabled, but do assert that the locking protocol is followed
> under DEBUG_VM regardless. Also remove the unused flags variable.
>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
mem_cgroup_split_huge_fixup is following the same pattern and might be
folded into this one. I can send a separate patch if you prefer, though.
---
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 3a203c7ec6c7..544e32292c7f 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3167,7 +3167,7 @@ static inline void memcg_unregister_all_caches(struct mem_cgroup *memcg)
*/
void mem_cgroup_split_huge_fixup(struct page *head)
{
- struct page_cgroup *head_pc = lookup_page_cgroup(head);
+ struct page_cgroup *head_pc;
struct page_cgroup *pc;
struct mem_cgroup *memcg;
int i;
@@ -3175,6 +3175,8 @@ void mem_cgroup_split_huge_fixup(struct page *head)
if (mem_cgroup_disabled())
return;
+ head_pc = lookup_page_cgroup(head);
+
memcg = head_pc->mem_cgroup;
for (i = 1; i < HPAGE_PMD_NR; i++) {
pc = head_pc + i;
--
Michal Hocko
SUSE Labs
^ permalink raw reply related [flat|nested] 2+ messages in thread
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