From 451ea25da71590361c71bf3044c55b870a887d53 Mon Sep 17 00:00:00 2001 From: Johannes Weiner Date: Mon, 21 Sep 2009 17:01:48 -0700 Subject: [PATCH] mm: perform non-atomic test-clear of PG_mlocked on free By the time PG_mlocked is cleared in the page freeing path, nobody else is looking at our page->flags anymore. It is thus safe to make the test-and-clear non-atomic and thereby removing an unnecessary and expensive operation from a hotpath. Signed-off-by: Johannes Weiner Reviewed-by: Christoph Lameter Reviewed-by: KOSAKI Motohiro Cc: Christoph Lameter Cc: Mel Gorman Cc: Nick Piggin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/page-flags.h | 12 +++++++++--- mm/page_alloc.c | 4 ++-- 2 files changed, 11 insertions(+), 5 deletions(-) diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 2b87acf..d07c0bb 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -158,6 +158,9 @@ static inline int TestSetPage##uname(struct page *page) \ static inline int TestClearPage##uname(struct page *page) \ { return test_and_clear_bit(PG_##lname, &page->flags); } +#define __TESTCLEARFLAG(uname, lname) \ +static inline int __TestClearPage##uname(struct page *page) \ + { return __test_and_clear_bit(PG_##lname, &page->flags); } #define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \ SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname) @@ -184,6 +187,9 @@ static inline void __ClearPage##uname(struct page *page) { } #define TESTCLEARFLAG_FALSE(uname) \ static inline int TestClearPage##uname(struct page *page) { return 0; } +#define __TESTCLEARFLAG_FALSE(uname) \ +static inline int __TestClearPage##uname(struct page *page) { return 0; } + struct page; /* forward declaration */ TESTPAGEFLAG(Locked, locked) TESTSETFLAG(Locked, locked) @@ -250,11 +256,11 @@ PAGEFLAG(Unevictable, unevictable) __CLEARPAGEFLAG(Unevictable, unevictable) #ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT #define MLOCK_PAGES 1 PAGEFLAG(Mlocked, mlocked) __CLEARPAGEFLAG(Mlocked, mlocked) - TESTSCFLAG(Mlocked, mlocked) + TESTSCFLAG(Mlocked, mlocked) __TESTCLEARFLAG(Mlocked, mlocked) #else #define MLOCK_PAGES 0 -PAGEFLAG_FALSE(Mlocked) - SETPAGEFLAG_NOOP(Mlocked) TESTCLEARFLAG_FALSE(Mlocked) +PAGEFLAG_FALSE(Mlocked) SETPAGEFLAG_NOOP(Mlocked) + TESTCLEARFLAG_FALSE(Mlocked) __TESTCLEARFLAG_FALSE(Mlocked) #endif #ifdef CONFIG_ARCH_USES_PG_UNCACHED diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 81926c7..9242d13 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -557,7 +557,7 @@ static void __free_pages_ok(struct page *page, unsigned int order) unsigned long flags; int i; int bad = 0; - int wasMlocked = TestClearPageMlocked(page); + int wasMlocked = __TestClearPageMlocked(page); kmemcheck_free_shadow(page, order); @@ -1026,7 +1026,7 @@ static void free_hot_cold_page(struct page *page, int cold) struct zone *zone = page_zone(page); struct per_cpu_pages *pcp; unsigned long flags; - int wasMlocked = TestClearPageMlocked(page); + int wasMlocked = __TestClearPageMlocked(page); kmemcheck_free_shadow(page, 0); -- 1.8.2.3