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 <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index e2f8e7c..cee3761 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -163,7 +163,7 @@
void mem_cgroup_count_vm_event(struct mm_struct *mm, enum vm_event_item idx);
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-void mem_cgroup_split_huge_fixup(struct page *head, struct page *tail);
+void mem_cgroup_split_huge_fixup(struct page *head);
#endif
#ifdef CONFIG_DEBUG_VM
@@ -379,8 +379,7 @@
return 0;
}
-static inline void mem_cgroup_split_huge_fixup(struct page *head,
- struct page *tail)
+static inline void mem_cgroup_split_huge_fixup(struct page *head)
{
}