From e94c8a9cbce1aee4af9e1285802785481b7f93c5 Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki Date: Thu, 12 Jan 2012 17:18:20 -0800 Subject: memcg: make mem_cgroup_split_huge_fixup() more efficient In split_huge_page(), mem_cgroup_split_huge_fixup() is called to handle page_cgroup modifcations. It takes move_lock_page_cgroup() and modifies page_cgroup and LRU accounting jobs and called HPAGE_PMD_SIZE - 1 times. But thinking again, - compound_lock() is held at move_accout...then, it's not necessary to take move_lock_page_cgroup(). - LRU is locked and all tail pages will go into the same LRU as head is now on. - page_cgroup is contiguous in huge page range. This patch fixes mem_cgroup_split_huge_fixup() as to be called once per hugepage and reduce costs for spliting. [akpm@linux-foundation.org: fix typo, per Michal] Signed-off-by: KAMEZAWA Hiroyuki Cc: Johannes Weiner Cc: Andrea Arcangeli Reviewed-by: Michal Hocko Cc: Balbir Singh Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/huge_memory.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'mm/huge_memory.c') diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 36b3d98..db522e1 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1207,6 +1207,8 @@ static void __split_huge_page_refcount(struct page *page) /* prevent PageLRU to go away from under us, and freeze lru stats */ spin_lock_irq(&zone->lru_lock); compound_lock(page); + /* complete memcg works before add pages to LRU */ + mem_cgroup_split_huge_fixup(page); for (i = 1; i < HPAGE_PMD_NR; i++) { struct page *page_tail = page + i; @@ -1278,7 +1280,6 @@ static void __split_huge_page_refcount(struct page *page) BUG_ON(!PageDirty(page_tail)); BUG_ON(!PageSwapBacked(page_tail)); - mem_cgroup_split_huge_fixup(page, page_tail); lru_add_page_tail(zone, page, page_tail); } -- cgit v1.1