memcg: fix documentation

The description about various statistics from memory.stat is not accurate
and confusing at times.

Correct this along with a few other minor cleanups.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 32 insertions, 23 deletions

diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index a98a7fe7aabb..1a608877b14e 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -6,15 +6,14 @@ used here with the memory controller that is used in hardware.
 
 Salient features
 
-a. Enable control of both RSS (mapped) and Page Cache (unmapped) pages
+a. Enable control of Anonymous, Page Cache (mapped and unmapped) and
+   Swap Cache memory pages.
 b. The infrastructure allows easy addition of other types of memory to control
 c. Provides *zero overhead* for non memory controller users
 d. Provides a double LRU: global memory pressure causes reclaim from the
    global LRU; a cgroup on hitting a limit, reclaims from the per
    cgroup LRU
 
-NOTE: Swap Cache (unmapped) is not accounted now.
-
 Benefits and Purpose of the memory controller
 
 The memory controller isolates the memory behaviour of a group of tasks
@@ -290,34 +289,44 @@ will be charged as a new owner of it.
   moved to the parent. If you want to avoid that, force_empty will be useful.
 
 5.2 stat file
-  memory.stat file includes following statistics (now)
-        cache                   - # of pages from page-cache and shmem.
-        rss                     - # of pages from anonymous memory.
-        pgpgin                  - # of event of charging
-        pgpgout                 - # of event of uncharging
-        active_anon             - # of pages on active lru of anon, shmem.
-        inactive_anon           - # of pages on active lru of anon, shmem
-        active_file             - # of pages on active lru of file-cache
-        inactive_file           - # of pages on inactive lru of file cache
-        unevictable             - # of pages cannot be reclaimed.(mlocked etc)
-
-        Below is depend on CONFIG_DEBUG_VM.
-        inactive_ratio          - VM internal parameter. (see mm/page_alloc.c)
-        recent_rotated_anon     - VM internal parameter. (see mm/vmscan.c)
-        recent_rotated_file     - VM internal parameter. (see mm/vmscan.c)
-        recent_scanned_anon     - VM internal parameter. (see mm/vmscan.c)
-        recent_scanned_file     - VM internal parameter. (see mm/vmscan.c)
-
-  Memo:
+
+memory.stat file includes following statistics
+
+cache           - # of bytes of page cache memory.
+rss             - # of bytes of anonymous and swap cache memory.
+pgpgin          - # of pages paged in (equivalent to # of charging events).
+pgpgout         - # of pages paged out (equivalent to # of uncharging events).
+active_anon     - # of bytes of anonymous and  swap cache memory on active
+                  lru list.
+inactive_anon   - # of bytes of anonymous memory and swap cache memory on
+                  inactive lru list.
+active_file     - # of bytes of file-backed memory on active lru list.
+inactive_file   - # of bytes of file-backed memory on inactive lru list.
+unevictable     - # of bytes of memory that cannot be reclaimed (mlocked etc).
+
+The following additional stats are dependent on CONFIG_DEBUG_VM.
+
+inactive_ratio          - VM internal parameter. (see mm/page_alloc.c)
+recent_rotated_anon     - VM internal parameter. (see mm/vmscan.c)
+recent_rotated_file     - VM internal parameter. (see mm/vmscan.c)
+recent_scanned_anon     - VM internal parameter. (see mm/vmscan.c)
+recent_scanned_file     - VM internal parameter. (see mm/vmscan.c)
+
+Memo:
         recent_rotated means recent frequency of lru rotation.
         recent_scanned means recent # of scans to lru.
         showing for better debug please see the code for meanings.
 
+Note:
+        Only anonymous and swap cache memory is listed as part of 'rss' stat.
+        This should not be confused with the true 'resident set size' or the
+        amount of physical memory used by the cgroup. Per-cgroup rss
+        accounting is not done yet.
 
 5.3 swappiness
   Similar to /proc/sys/vm/swappiness, but affecting a hierarchy of groups only.
 
-  Following cgroup's swapiness can't be changed.
+  Following cgroups' swapiness can't be changed.
   - root cgroup (uses /proc/sys/vm/swappiness).
   - a cgroup which uses hierarchy and it has child cgroup.
   - a cgroup which uses hierarchy and not the root of hierarchy.