memcg: document cgroup dirty/writeback memory statistics

Signed-off-by: Sha Zhengju <handai.szj@taobao.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index 2a33306963727fba16c047610d9738b1076db38e..8af4ad12182869c4f972eeb9a5029c35e383b19a 100644 (file)
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -490,6 +490,8 @@ pgpgin              - # of charging events to the memory cgroup. The charging
 pgpgout                - # of uncharging events to the memory cgroup. The uncharging
                event happens each time a page is unaccounted from the cgroup.
 swap           - # of bytes of swap usage
+writeback      - # of bytes of file/anon cache that are queued for syncing to
+               disk.
 inactive_anon  - # of bytes of anonymous and swap cache memory on inactive
                LRU list.
 active_anon    - # of bytes of anonymous and swap cache memory on active