From 89e004ea55abe201b29e2d6e35124101f1288ef7 Mon Sep 17 00:00:00 2001 From: Lee Schermerhorn Date: Sat, 18 Oct 2008 20:26:43 -0700 Subject: SHM_LOCKED pages are unevictable Shmem segments locked into memory via shmctl(SHM_LOCKED) should not be kept on the normal LRU, since scanning them is a waste of time and might throw off kswapd's balancing algorithms. Place them on the unevictable LRU list instead. Use the AS_UNEVICTABLE flag to mark address_space of SHM_LOCKed shared memory regions as unevictable. Then these pages will be culled off the normal LRU lists during vmscan. Add new wrapper function to clear the mapping's unevictable state when/if shared memory segment is munlocked. Add 'scan_mapping_unevictable_page()' to mm/vmscan.c to scan all pages in the shmem segment's mapping [struct address_space] for evictability now that they're no longer locked. If so, move them to the appropriate zone lru list. Changes depend on [CONFIG_]UNEVICTABLE_LRU. [kosaki.motohiro@jp.fujitsu.com: revert shm change] Signed-off-by: Lee Schermerhorn Signed-off-by: Rik van Riel Signed-off-by: Kosaki Motohiro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/pagemap.h | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) (limited to 'include/linux/pagemap.h') diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 09164d2c5c27..4b6c4d8d26b8 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -40,14 +40,20 @@ static inline void mapping_set_unevictable(struct address_space *mapping) set_bit(AS_UNEVICTABLE, &mapping->flags); } +static inline void mapping_clear_unevictable(struct address_space *mapping) +{ + clear_bit(AS_UNEVICTABLE, &mapping->flags); +} + static inline int mapping_unevictable(struct address_space *mapping) { - if (mapping && (mapping->flags & AS_UNEVICTABLE)) - return 1; - return 0; + if (likely(mapping)) + return test_bit(AS_UNEVICTABLE, &mapping->flags); + return !!mapping; } #else static inline void mapping_set_unevictable(struct address_space *mapping) { } +static inline void mapping_clear_unevictable(struct address_space *mapping) { } static inline int mapping_unevictable(struct address_space *mapping) { return 0; -- cgit v1.2.1