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| author | Johannes Weiner <hannes@cmpxchg.org> | 2009-09-21 17:01:48 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-22 07:17:30 -0700 |
| commit | 451ea25da71590361c71bf3044c55b870a887d53 (patch) | |
| tree | e2e9de6e7c1fb4f79c0413a3c4d401ec9263b722 | |
| parent | bf88c8c83e4425d17e29daa5354ffb1f8ba7b225 (diff) | |
| download | blackbird-op-linux-451ea25da71590361c71bf3044c55b870a887d53.tar.gz blackbird-op-linux-451ea25da71590361c71bf3044c55b870a887d53.zip | |
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 <hannes@cmpxchg.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | include/linux/page-flags.h | 12 | ||||
| -rw-r--r-- | 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 2b87acfc5f87..d07c0bb2203a 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 81926c7ef6f0..9242d13f4ff3 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); |
