[PATCH] mm, swap_state.c: declare a few variables as __read_mostly

[changbin . du]

From: Changbin Du <changbin.du@xxxxxxxxx>

These global variables are only set during initialization or rarely
change, so declare them as __read_mostly.

Signed-off-by: Changbin Du <changbin.du@xxxxxxxxx>
---
 mm/swap_state.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/swap_state.c b/mm/swap_state.c
index ed91091..71e667d 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -35,13 +35,13 @@ static const struct address_space_operations swap_aops = {
 #endif
 };
 
-struct address_space *swapper_spaces[MAX_SWAPFILES];
-static unsigned int nr_swapper_spaces[MAX_SWAPFILES];
-bool swap_vma_readahead = true;
+struct address_space *swapper_spaces[MAX_SWAPFILES] __read_mostly;
+static unsigned int nr_swapper_spaces[MAX_SWAPFILES] __read_mostly;
+bool swap_vma_readahead __read_mostly = true;
 
 #define SWAP_RA_MAX_ORDER_DEFAULT	3
 
-static int swap_ra_max_order = SWAP_RA_MAX_ORDER_DEFAULT;
+static int swap_ra_max_order __read_mostly = SWAP_RA_MAX_ORDER_DEFAULT;
 
 #define SWAP_RA_WIN_SHIFT	(PAGE_SHIFT / 2)
 #define SWAP_RA_HITS_MASK	((1UL << SWAP_RA_WIN_SHIFT) - 1)
-- 
2.7.4