[PATCH v2 6/6] mm: lru_add_drain_all() do local lru_add_drain() first

[Hugh Dickins]

No numbers to back this up, but it seemed obvious to me, that if there
are competing lru_add_drain_all()ers, the work will be minimized if each
flushes its own local queues before locking and doing cross-CPU drains.

Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
---
 mm/swap.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/swap.c b/mm/swap.c
index b74ebe865dd9..881e53b2877e 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -834,6 +834,9 @@ static inline void __lru_add_drain_all(bool force_all_cpus)
 	 */
 	this_gen = smp_load_acquire(&lru_drain_gen);
 
+	/* It helps everyone if we do our own local drain immediately. */
+	lru_add_drain();
+
 	mutex_lock(&lock);
 
 	/*
-- 
2.51.0