From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 18 Aug 2008 14:24:28 +0200 From: Nick Piggin Subject: [patch] mm: pagecache insertion fewer atomics Message-ID: <20080818122428.GA9062@wotan.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton , Linux Memory Management List List-ID: Setting and clearing the page locked when inserting it into swapcache / pagecache when it has no other references can use non-atomic page flags operations because no other CPU may be operating on it at this time. This saves one atomic operation when inserting a page into pagecache. Signed-off-by: Nick Piggin --- include/linux/pagemap.h | 37 +++++++++++++++++++++++++++++++++---- mm/swap_state.c | 4 ++-- 2 files changed, 35 insertions(+), 6 deletions(-) Index: linux-2.6/mm/swap_state.c =================================================================== --- linux-2.6.orig/mm/swap_state.c +++ linux-2.6/mm/swap_state.c @@ -302,7 +302,7 @@ struct page *read_swap_cache_async(swp_e * re-using the just freed swap entry for an existing page. * May fail (-ENOMEM) if radix-tree node allocation failed. */ - set_page_locked(new_page); + __set_page_locked(new_page); err = add_to_swap_cache(new_page, entry, gfp_mask & GFP_KERNEL); if (likely(!err)) { /* @@ -312,7 +312,7 @@ struct page *read_swap_cache_async(swp_e swap_readpage(NULL, new_page); return new_page; } - clear_page_locked(new_page); + __clear_page_locked(new_page); swap_free(entry); } while (err != -ENOMEM); Index: linux-2.6/include/linux/pagemap.h =================================================================== --- linux-2.6.orig/include/linux/pagemap.h +++ linux-2.6/include/linux/pagemap.h @@ -271,14 +271,14 @@ extern int __lock_page_killable(struct p extern void __lock_page_nosync(struct page *page); extern void unlock_page(struct page *page); -static inline void set_page_locked(struct page *page) +static inline void __set_page_locked(struct page *page) { - set_bit(PG_locked, &page->flags); + __set_bit(PG_locked, &page->flags); } -static inline void clear_page_locked(struct page *page) +static inline void __clear_page_locked(struct page *page) { - clear_bit(PG_locked, &page->flags); + __clear_bit(PG_locked, &page->flags); } static inline int trylock_page(struct page *page) @@ -410,17 +410,17 @@ extern void __remove_from_page_cache(str /* * Like add_to_page_cache_locked, but used to add newly allocated pages: - * the page is new, so we can just run set_page_locked() against it. + * the page is new, so we can just run __set_page_locked() against it. */ static inline int add_to_page_cache(struct page *page, struct address_space *mapping, pgoff_t offset, gfp_t gfp_mask) { int error; - set_page_locked(page); + __set_page_locked(page); error = add_to_page_cache_locked(page, mapping, offset, gfp_mask); if (unlikely(error)) - clear_page_locked(page); + __clear_page_locked(page); return error; } -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org