[PATCH v3 1/7] mm/lru: add per lruvec lock for memcg

[Alex Shi <alex.shi@linux.alibaba.com>]

Currently memcg still use per node pgdat->lru_lock to guard its lruvec.
That causes some lru_lock contention in a high container density system.

If we can use per lruvec lock, that could relief much of the lru_lock
contention.

The later patches will replace the pgdat->lru_lock with lruvec->lru_lock
and show the performance benefit by benchmarks.

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Arun KS <arunks@codeaurora.org>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Hugh Dickins <hughd@google.com>
Cc: cgroups@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
 include/linux/mmzone.h | 2 ++
 mm/mmzone.c            | 1 +
 2 files changed, 3 insertions(+)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 07b784ffbb14..a13b8a602ee5 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -267,6 +267,8 @@ struct lruvec {
 	unsigned long			refaults;
 	/* Various lruvec state flags (enum lruvec_flags) */
 	unsigned long			flags;
+	/* per lruvec lru_lock for memcg */
+	spinlock_t			lru_lock;
 #ifdef CONFIG_MEMCG
 	struct pglist_data *pgdat;
 #endif
diff --git a/mm/mmzone.c b/mm/mmzone.c
index 4686fdc23bb9..3750a90ed4a0 100644
--- a/mm/mmzone.c
+++ b/mm/mmzone.c
@@ -91,6 +91,7 @@ void lruvec_init(struct lruvec *lruvec)
 	enum lru_list lru;
 
 	memset(lruvec, 0, sizeof(struct lruvec));
+	spin_lock_init(&lruvec->lru_lock);
 
 	for_each_lru(lru)
 		INIT_LIST_HEAD(&lruvec->lists[lru]);
-- 
1.8.3.1