[PATCH 2/2] pagevec: Increase the size of LRU pagevecs

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

Tim Chen reports that increasing the size of LRU pagevecs is advantageous
with a workload he has:
https://lore.kernel.org/linux-mm/d1cc9f12a8ad6c2a52cb600d93b06b064f2bbc57.1593205965.git.tim.c.chen@linux.intel.com/

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/pagevec.h |  5 +++++
 mm/swap.c               | 27 +++++++++++++++------------
 2 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/include/linux/pagevec.h b/include/linux/pagevec.h
index ee5d3c4da8da..4dc45392d776 100644
--- a/include/linux/pagevec.h
+++ b/include/linux/pagevec.h
@@ -29,6 +29,11 @@ struct pagevec {
 	};
 };
 
+#define declare_pagevec(name, size) union {				\
+	struct pagevec name;						\
+	void *__p ##name [size + 1];					\
+}
+
 void __pagevec_release(struct pagevec *pvec);
 void __pagevec_lru_add(struct pagevec *pvec);
 void pagevec_remove_exceptionals(struct pagevec *pvec);
diff --git a/mm/swap.c b/mm/swap.c
index d093fb30f038..1e6f50b312ea 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -45,14 +45,17 @@
 /* How many pages do we try to swap or page in/out together? */
 int page_cluster;
 
+#define LRU_PAGEVEC_SIZE 63
+#define lru_pagevec(name)	declare_pagevec(name, LRU_PAGEVEC_SIZE)
+
 /* Protecting only lru_rotate.pvec which requires disabling interrupts */
 struct lru_rotate {
 	local_lock_t lock;
-	struct pagevec pvec;
+	lru_pagevec(pvec);
 };
 static DEFINE_PER_CPU(struct lru_rotate, lru_rotate) = {
 	.lock = INIT_LOCAL_LOCK(lock),
-	.pvec.sz = PAGEVEC_SIZE,
+	.pvec.sz = LRU_PAGEVEC_SIZE,
 };
 
 /*
@@ -61,22 +64,22 @@ static DEFINE_PER_CPU(struct lru_rotate, lru_rotate) = {
  */
 struct lru_pvecs {
 	local_lock_t lock;
-	struct pagevec lru_add;
-	struct pagevec lru_deactivate_file;
-	struct pagevec lru_deactivate;
-	struct pagevec lru_lazyfree;
+	lru_pagevec(lru_add);
+	lru_pagevec(lru_deactivate_file);
+	lru_pagevec(lru_deactivate);
+	lru_pagevec(lru_lazyfree);
 #ifdef CONFIG_SMP
-	struct pagevec activate_page;
+	lru_pagevec(activate_page);
 #endif
 };
 static DEFINE_PER_CPU(struct lru_pvecs, lru_pvecs) = {
 	.lock = INIT_LOCAL_LOCK(lock),
-	.lru_add.sz = PAGEVEC_SIZE,
-	.lru_deactivate_file.sz = PAGEVEC_SIZE,
-	.lru_deactivate.sz = PAGEVEC_SIZE,
-	.lru_lazyfree.sz = PAGEVEC_SIZE,
+	.lru_add.sz = LRU_PAGEVEC_SIZE,
+	.lru_deactivate_file.sz = LRU_PAGEVEC_SIZE,
+	.lru_deactivate.sz = LRU_PAGEVEC_SIZE,
+	.lru_lazyfree.sz = LRU_PAGEVEC_SIZE,
 #ifdef CONFIG_SMP
-	.activate_page.sz = PAGEVEC_SIZE,
+	.activate_page.sz = LRU_PAGEVEC_SIZE,
 #endif
 };
 
-- 
2.28.0