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authorHugh Dickins <hugh.dickins@tiscali.co.uk>2009-09-21 20:02:10 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-22 10:17:32 -0400
commite178dfde3952192cf44eeb0612882f01fc96c0a9 (patch)
tree874b8dd5c2ebba6889621b14e01b7d503a098e4d
parentb4028260334e1ecf63fb5e0a95d65bb2db02c1ec (diff)
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>
-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;
152/* The number of nodes in the stable tree */ 152/* The number of nodes in the stable tree */
153static unsigned long ksm_pages_shared; 153static unsigned long ksm_pages_shared;
154 154
155/* The number of page slots sharing those nodes */ 155/* The number of page slots additionally sharing those nodes */
156static unsigned long ksm_pages_sharing; 156static unsigned long ksm_pages_sharing;
157 157
158/* Limit on the number of unswappable pages used */ 158/* Limit on the number of unswappable pages used */
@@ -382,6 +382,7 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
382 &next_item->node, 382 &next_item->node,
383 &root_stable_tree); 383 &root_stable_tree);
384 next_item->address |= NODE_FLAG; 384 next_item->address |= NODE_FLAG;
385 ksm_pages_sharing--;
385 } else { 386 } else {
386 rb_erase(&rmap_item->node, &root_stable_tree); 387 rb_erase(&rmap_item->node, &root_stable_tree);
387 ksm_pages_shared--; 388 ksm_pages_shared--;
@@ -395,10 +396,10 @@ static void remove_rmap_item_from_tree(struct rmap_item *rmap_item)
395 BUG_ON(next_item->prev != rmap_item); 396 BUG_ON(next_item->prev != rmap_item);
396 next_item->prev = rmap_item->prev; 397 next_item->prev = rmap_item->prev;
397 } 398 }
399 ksm_pages_sharing--;
398 } 400 }
399 401
400 rmap_item->next = NULL; 402 rmap_item->next = NULL;
401 ksm_pages_sharing--;
402 403
403 } else if (rmap_item->address & NODE_FLAG) { 404 } else if (rmap_item->address & NODE_FLAG) {
404 unsigned char age; 405 unsigned char age;
@@ -786,8 +787,6 @@ static int try_to_merge_two_pages(struct mm_struct *mm1, unsigned long addr1,
786 */ 787 */
787 if (err) 788 if (err)
788 break_cow(mm1, addr1); 789 break_cow(mm1, addr1);
789 else
790 ksm_pages_sharing += 2;
791 } 790 }
792 791
793 put_page(kpage); 792 put_page(kpage);
@@ -816,9 +815,6 @@ static int try_to_merge_with_ksm_page(struct mm_struct *mm1,
816 err = try_to_merge_one_page(vma, page1, kpage); 815 err = try_to_merge_one_page(vma, page1, kpage);
817 up_read(&mm1->mmap_sem); 816 up_read(&mm1->mmap_sem);
818 817
819 if (!err)
820 ksm_pages_sharing++;
821
822 return err; 818 return err;
823} 819}
824 820
@@ -928,13 +924,12 @@ static struct rmap_item *stable_tree_insert(struct page *page,
928 } 924 }
929 } 925 }
930 926
931 ksm_pages_shared++;
932
933 rmap_item->address |= NODE_FLAG | STABLE_FLAG; 927 rmap_item->address |= NODE_FLAG | STABLE_FLAG;
934 rmap_item->next = NULL; 928 rmap_item->next = NULL;
935 rb_link_node(&rmap_item->node, parent, new); 929 rb_link_node(&rmap_item->node, parent, new);
936 rb_insert_color(&rmap_item->node, &root_stable_tree); 930 rb_insert_color(&rmap_item->node, &root_stable_tree);
937 931
932 ksm_pages_shared++;
938 return rmap_item; 933 return rmap_item;
939} 934}
940 935
@@ -1019,6 +1014,8 @@ static void stable_tree_append(struct rmap_item *rmap_item,
1019 1014
1020 tree_rmap_item->next = rmap_item; 1015 tree_rmap_item->next = rmap_item;
1021 rmap_item->address |= STABLE_FLAG; 1016 rmap_item->address |= STABLE_FLAG;
1017
1018 ksm_pages_sharing++;
1022} 1019}
1023 1020
1024/* 1021/*
@@ -1043,10 +1040,9 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item)
1043 /* We first start with searching the page inside the stable tree */ 1040 /* We first start with searching the page inside the stable tree */
1044 tree_rmap_item = stable_tree_search(page, page2, rmap_item); 1041 tree_rmap_item = stable_tree_search(page, page2, rmap_item);
1045 if (tree_rmap_item) { 1042 if (tree_rmap_item) {
1046 if (page == page2[0]) { /* forked */ 1043 if (page == page2[0]) /* forked */
1047 ksm_pages_sharing++;
1048 err = 0; 1044 err = 0;
1049 } else 1045 else
1050 err = try_to_merge_with_ksm_page(rmap_item->mm, 1046 err = try_to_merge_with_ksm_page(rmap_item->mm,
1051 rmap_item->address, 1047 rmap_item->address,
1052 page, page2[0]); 1048 page, page2[0]);
@@ -1107,7 +1103,6 @@ static void cmp_and_merge_page(struct page *page, struct rmap_item *rmap_item)
1107 break_cow(tree_rmap_item->mm, 1103 break_cow(tree_rmap_item->mm,
1108 tree_rmap_item->address); 1104 tree_rmap_item->address);
1109 break_cow(rmap_item->mm, rmap_item->address); 1105 break_cow(rmap_item->mm, rmap_item->address);
1110 ksm_pages_sharing -= 2;
1111 } 1106 }
1112 } 1107 }
1113 1108
@@ -1475,8 +1470,7 @@ KSM_ATTR_RO(pages_shared);
1475static ssize_t pages_sharing_show(struct kobject *kobj, 1470static ssize_t pages_sharing_show(struct kobject *kobj,
1476 struct kobj_attribute *attr, char *buf) 1471 struct kobj_attribute *attr, char *buf)
1477{ 1472{
1478 return sprintf(buf, "%lu\n", 1473 return sprintf(buf, "%lu\n", ksm_pages_sharing);
1479 ksm_pages_sharing - ksm_pages_shared);
1480} 1474}
1481KSM_ATTR_RO(pages_sharing); 1475KSM_ATTR_RO(pages_sharing);
1482 1476