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authorHugh Dickins <hugh.dickins@tiscali.co.uk>2009-09-21 17:02:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-22 07:17:32 -0700
commite178dfde3952192cf44eeb0612882f01fc96c0a9 (patch)
tree874b8dd5c2ebba6889621b14e01b7d503a098e4d
parentksm: rename kernel_pages_allocated (diff)
downloadlinux-dev-e178dfde3952192cf44eeb0612882f01fc96c0a9.tar.xz
linux-dev-e178dfde3952192cf44eeb0612882f01fc96c0a9.zip
ksm: move pages_sharing updates
The pages_shared count is incremented and decremented when adding a node to and removing a node from the stable tree: easy to understand. But the pages_sharing count was hard to follow, being adjusted in various places: increment and decrement it when adding to and removing from the stable tree. And the pages_sharing variable used to include the pages_shared, then those were subtracted when shown in the pages_sharing sysfs file: now keep it as an exclusive count of leaves hanging off the stable tree nodes, throughout. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Acked-by: Izik Eidus <ieidus@redhat.com> Acked-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
-rw-r--r--mm/ksm.c24
1 files changed, 9 insertions, 15 deletions
diff --git a/mm/ksm.c b/mm/ksm.c
index 46b4c522ea4f..ef89526fb862 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -152,7 +152,7 @@ static struct kmem_cache *mm_slot_cache;
/* The number of nodes in the stable tree */
static unsigned long ksm_pages_shared;
-/* The number of page slots sharing those nodes */
+/* The number of page slots additionally sharing those nodes */
static unsigned long ksm_pages_sharing;
/* Limit on the number of unswappable pages used */
@@ -382,6 +382,7 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
&next_item->node,
&root_stable_tree);
next_item->address |= NODE_FLAG;
+ ksm_pages_sharing--;
} else {
rb_erase(&rmap_item->node, &root_stable_tree);
ksm_pages_shared--;
@@ -395,10 +396,10 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
BUG_ON(next_item->prev != rmap_item);
next_item->prev = rmap_item->prev;
}
+ ksm_pages_sharing--;
}
rmap_item->next = NULL;
- ksm_pages_sharing--;
} else if (rmap_item->address & NODE_FLAG) {
unsigned char age;
@@ -786,8 +787,6 @@ static int try_to_merge_two_pages(struct mm_struct *mm1, unsigned long addr1,
*/
if (err)
break_cow(mm1, addr1);
- else
- ksm_pages_sharing += 2;
}
put_page(kpage);
@@ -816,9 +815,6 @@ static int try_to_merge_with_ksm_page(struct mm_struct *mm1,
err = try_to_merge_one_page(vma, page1, kpage);
up_read(&mm1->mmap_sem);
- if (!err)
- ksm_pages_sharing++;
-
return err;
}
@@ -928,13 +924,12 @@ static struct rmap_item *stable_tree_insert(struct page *page,
}
}
- ksm_pages_shared++;
-
rmap_item->address |= NODE_FLAG | STABLE_FLAG;
rmap_item->next = NULL;
rb_link_node(&rmap_item->node, parent, new);
rb_insert_color(&rmap_item->node, &root_stable_tree);
+ ksm_pages_shared++;
return rmap_item;
}
@@ -1019,6 +1014,8 @@ static void stable_tree_append(struct rmap_item *rmap_item,
tree_rmap_item->next = rmap_item;
rmap_item->address |= STABLE_FLAG;
+
+ ksm_pages_sharing++;
}
/*
@@ -1043,10 +1040,9 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item)
/* We first start with searching the page inside the stable tree */
tree_rmap_item = stable_tree_search(page, page2, rmap_item);
if (tree_rmap_item) {
- if (page == page2[0]) { /* forked */
- ksm_pages_sharing++;
+ if (page == page2[0]) /* forked */
err = 0;
- } else
+ else
err = try_to_merge_with_ksm_page(rmap_item->mm,
rmap_item->address,
page, page2[0]);
@@ -1107,7 +1103,6 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item)
break_cow(tree_rmap_item->mm,
tree_rmap_item->address);
break_cow(rmap_item->mm, rmap_item->address);
- ksm_pages_sharing -= 2;
}
}
@@ -1475,8 +1470,7 @@ KSM_ATTR_RO(pages_shared);
static ssize_t pages_sharing_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
- return sprintf(buf, "%lu\n",
- ksm_pages_sharing - ksm_pages_shared);
+ return sprintf(buf, "%lu\n", ksm_pages_sharing);
}
KSM_ATTR_RO(pages_sharing);