path: root/Documentation
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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2008-10-18 20:28:10 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-10-20 08:52:38 -0700
commit5b4e655e948d8b6e9b0d001616d4c9d7e7ffe924 (patch)
tree2822f944d1bdbc8414a65cd94b982c51b5032b50 /Documentation
parentb7abea9630bc8ffc663a751e46680db25c4cdf8d (diff)
memcg: avoid accounting special pages
There are not-on-LRU pages which can be mapped and they are not worth to be accounted. (becasue we can't shrink them and need dirty codes to handle specical case) We'd like to make use of usual objrmap/radix-tree's protcol and don't want to account out-of-vm's control pages. When special_mapping_fault() is called, page->mapping is tend to be NULL and it's charged as Anonymous page. insert_page() also handles some special pages from drivers. This patch is for avoiding to account special pages. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Cc: Balbir Singh <balbir@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation')
1 files changed, 16 insertions, 8 deletions
diff --git a/Documentation/controllers/memory.txt b/Documentation/controllers/memory.txt
index 9b53d582736..1c07547d3f8 100644
--- a/Documentation/controllers/memory.txt
+++ b/Documentation/controllers/memory.txt
@@ -112,14 +112,22 @@ the per cgroup LRU.
2.2.1 Accounting details
-All mapped pages (RSS) and unmapped user pages (Page Cache) are accounted.
-RSS pages are accounted at the time of page_add_*_rmap() unless they've already
-been accounted for earlier. A file page will be accounted for as Page Cache;
-it's mapped into the page tables of a process, duplicate accounting is carefully
-avoided. Page Cache pages are accounted at the time of add_to_page_cache().
-The corresponding routines that remove a page from the page tables or removes
-a page from Page Cache is used to decrement the accounting counters of the
+All mapped anon pages (RSS) and cache pages (Page Cache) are accounted.
+(some pages which never be reclaimable and will not be on global LRU
+ are not accounted. we just accounts pages under usual vm management.)
+RSS pages are accounted at page_fault unless they've already been accounted
+for earlier. A file page will be accounted for as Page Cache when it's
+inserted into inode (radix-tree). While it's mapped into the page tables of
+processes, duplicate accounting is carefully avoided.
+A RSS page is unaccounted when it's fully unmapped. A PageCache page is
+unaccounted when it's removed from radix-tree.
+At page migration, accounting information is kept.
+Note: we just account pages-on-lru because our purpose is to control amount
+of used pages. not-on-lru pages are tend to be out-of-control from vm view.
2.3 Shared Page Accounting