[PATCH 1/6] memcg: move per-node objcg to the read-mostly fields

[Shakeel Butt]

current_obj_cgroup() reads memcg->nodeinfo[nid]->objcg on every
accounted allocation. The field sits at the end of struct
mem_cgroup_per_node, on the same cache line as lru_zone_size[] and
iter. lru_zone_size[] is written on every LRU add and remove, and iter
is written on every reclaim iteration.

Move objcg next to the other read-mostly pointers at the start of the
struct.

No functional change.

Signed-off-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
---
 include/linux/memcontrol.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index f932b1ddda8c..ac575fcc5f1e 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -94,6 +94,7 @@ struct mem_cgroup_per_node {
 	struct lruvec_stats_percpu __percpu	*lruvec_stats_percpu;
 	struct lruvec_stats			*lruvec_stats;
 	struct shrinker_info __rcu	*shrinker_info;
+	struct obj_cgroup __rcu		*objcg;
 
 	CACHELINE_PADDING(_pad1_);
 
@@ -104,11 +105,9 @@ struct mem_cgroup_per_node {
 	struct mem_cgroup_reclaim_iter	iter;
 
 	/*
-	 * objcg is wiped out as a part of the objcg repaprenting process.
 	 * orig_objcg preserves a pointer (and a reference) to the original
-	 * objcg until the end of live of memcg.
+	 * objcg until the end of life of memcg.
 	 */
-	struct obj_cgroup __rcu	*objcg;
 	struct obj_cgroup	*orig_objcg;
 	/* list of inherited objcgs, protected by objcg_lock */
 	struct list_head objcg_list;
-- 
2.53.0-Meta