[Devel] [PATCH 08/13] mm/list_lru.c: set bit in memcg shrinker bitmap on first list_lru item appearance

[Kirill Tkhai]

ms commit fae91d6d8be5

Introduce set_shrinker_bit() function to set shrinker-related bit in
memcg shrinker bitmap, and set the bit after the first item is added and
in case of reparenting destroyed memcg's items.

This will allow next patch to make shrinkers be called only, in case of
they have charged objects at the moment, and to improve shrink_slab()
performance.

[ktkhai at virtuozzo.com: v9]
Link: http://lkml.kernel.org/r/153112557572.4097.17315791419810749985.stgit@localhost.localdomain
Link: http://lkml.kernel.org/r/153063065671.1818.15914674956134687268.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev at gmail.com>
Tested-by: Shakeel Butt <shakeelb at google.com>
Cc: Al Viro <viro at zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin at virtuozzo.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Cc: Guenter Roeck <linux at roeck-us.net>
Cc: "Huang, Ying" <ying.huang at intel.com>
Cc: Johannes Weiner <hannes at cmpxchg.org>
Cc: Josef Bacik <jbacik at fb.com>
Cc: Li RongQing <lirongqing at baidu.com>
Cc: Matthew Wilcox <willy at infradead.org>
Cc: Matthias Kaehlcke <mka at chromium.org>
Cc: Mel Gorman <mgorman at techsingularity.net>
Cc: Michal Hocko <mhocko at kernel.org>
Cc: Minchan Kim <minchan at kernel.org>
Cc: Philippe Ombredanne <pombredanne at nexb.com>
Cc: Roman Gushchin <guro at fb.com>
Cc: Sahitya Tummala <stummala at codeaurora.org>
Cc: Stephen Rothwell <sfr at canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: Waiman Long <longman at redhat.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
 include/linux/memcontrol.h |    4 ++++
 mm/list_lru.c              |   24 ++++++++++++++++++++++--
 mm/memcontrol.c            |   12 ++++++++++++
 3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 4d881adf12b5..6270653cfb91 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -633,6 +633,8 @@ static __always_inline struct mem_cgroup *mem_cgroup_from_kmem(void *ptr)
 	return __mem_cgroup_from_kmem(ptr);
 }
 extern int memcg_expand_shrinker_maps(int new_id);
+extern void memcg_set_shrinker_bit(struct mem_cgroup *memcg,
+				   int nid, int shrinker_id);
 #else
 #define for_each_memcg_cache_index(_idx)	\
 	for (; NULL; )
@@ -692,6 +694,8 @@ static inline struct mem_cgroup *mem_cgroup_from_kmem(void *ptr)
 {
 	return NULL;
 }
+static inline void memcg_set_shrinker_bit(struct mem_cgroup *memcg,
+					  int nid, int shrinker_id) { }
 #endif /* CONFIG_MEMCG_KMEM */
 #endif /* _LINUX_MEMCONTROL_H */
 
diff --git a/mm/list_lru.c b/mm/list_lru.c
index aca7dd7da162..21e12a8364ff 100644
--- a/mm/list_lru.c
+++ b/mm/list_lru.c
@@ -29,6 +29,11 @@ static void list_lru_unregister(struct list_lru *lru)
 	list_del(&lru->list);
 	mutex_unlock(&list_lrus_mutex);
 }
+
+static int lru_shrinker_id(struct list_lru *lru)
+{
+	return lru->shrinker_id;
+}
 #else
 static void list_lru_register(struct list_lru *lru)
 {
@@ -37,6 +42,11 @@ static void list_lru_register(struct list_lru *lru)
 static void list_lru_unregister(struct list_lru *lru)
 {
 }
+
+static int lru_shrinker_id(struct list_lru *lru)
+{
+	return -1;
+}
 #endif /* CONFIG_MEMCG_KMEM */
 
 #ifdef CONFIG_MEMCG_KMEM
@@ -113,13 +123,18 @@ bool list_lru_add(struct list_lru *lru, struct list_head *item)
 {
 	int nid = page_to_nid(virt_to_page(item));
 	struct list_lru_node *nlru = &lru->node[nid];
+	struct mem_cgroup *memcg;
 	struct list_lru_one *l;
 
 	spin_lock(&nlru->lock);
-	l = list_lru_from_kmem(nlru, item, NULL);
+	l = list_lru_from_kmem(nlru, item, &memcg);
 	if (list_empty(item)) {
 		list_add_tail(item, &l->list);
-		l->nr_items++;
+		/* Set shrinker bit if the first element was added */
+		if (!l->nr_items++)
+			memcg_set_shrinker_bit(memcg, nid,
+					       lru_shrinker_id(lru));
+
 		spin_unlock(&nlru->lock);
 		return true;
 	}
@@ -496,6 +511,7 @@ static void memcg_drain_list_lru_node(struct list_lru *lru, int nid,
 	struct list_lru_node *nlru = &lru->node[nid];
 	int dst_idx = memcg_cache_id(dst_memcg);
 	struct list_lru_one *src, *dst;
+	bool set;
 
 	/*
 	 * Since list_lru_{add,del} may be called under an IRQ-safe lock,
@@ -507,9 +523,13 @@ static void memcg_drain_list_lru_node(struct list_lru *lru, int nid,
 	dst = list_lru_from_memcg_idx(nlru, dst_idx);
 
 	list_splice_init(&src->list, &dst->list);
+	set = (!dst->nr_items && src->nr_items);
 	dst->nr_items += src->nr_items;
+	if (set)
+		memcg_set_shrinker_bit(dst_memcg, nid, lru_shrinker_id(lru));
 	src->nr_items = 0;
 
+
 	spin_unlock_irq(&nlru->lock);
 }
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0ba355d1e47a..19d7d6553f59 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -824,6 +824,18 @@ int memcg_expand_shrinker_maps(int new_id)
 	mutex_unlock(&memcg_shrinker_map_mutex);
 	return ret;
 }
+
+void memcg_set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id)
+{
+	if (shrinker_id >= 0 && memcg && !mem_cgroup_is_root(memcg)) {
+		struct memcg_shrinker_map *map;
+
+		rcu_read_lock();
+		map = rcu_dereference(memcg->info.nodeinfo[nid]->shrinker_map);
+		set_bit(shrinker_id, map->map);
+		rcu_read_unlock();
+	}
+}
 #else
 static void disarm_kmem_keys(struct mem_cgroup *memcg)
 {