memcg: fix pgpgin/pgpgout documentation
The two memcg stats pgpgin/pgpgout have different meaning than the ones
in vmstat, which indicates that we picked a bad naming for them.
It might be late to change the stat name, but better documentation is
always helpful.
Signed-off-by: Ying Han <yinghan@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
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 c7de7da..4c95c00 100644
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -410,8 +410,11 @@
cache - # of bytes of page cache memory.
rss - # of bytes of anonymous and swap cache memory.
mapped_file - # of bytes of mapped file (includes tmpfs/shmem)
-pgpgin - # of pages paged in (equivalent to # of charging events).
-pgpgout - # of pages paged out (equivalent to # of uncharging events).
+pgpgin - # of charging events to the memory cgroup. The charging
+ event happens each time a page is accounted as either mapped
+ anon page(RSS) or cache page(Page Cache) to the cgroup.
+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
inactive_anon - # of bytes of anonymous memory and swap cache memory on
LRU list.