memcg: update memcg_test.txt

Update memcg_test.txt to describe how to test the move-charge feature.

Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 20 insertions, 2 deletions

diff --git a/Documentation/cgroups/memcg_test.txt b/Documentation/cgroups/memcg_test.txt
index 72db89ed0609..e01148886b5b 100644
--- a/Documentation/cgroups/memcg_test.txt
+++ b/Documentation/cgroups/memcg_test.txt
@@ -1,6 +1,6 @@
 Memory Resource Controller(Memcg)  Implementation Memo.
-Last Updated: 2009/1/20
-Base Kernel Version: based on 2.6.29-rc2.
+Last Updated: 2010/2
+Base Kernel Version: based on 2.6.33-rc7-mm(candidate for 34).
 
 Because VM is getting complex (one of reasons is memcg...), memcg's behavior
 is complex. This is a document for memcg's internal behavior.
@@ -378,3 +378,21 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y.
         #echo 50M > memory.limit_in_bytes
         #echo 50M > memory.memsw.limit_in_bytes
         run 51M of malloc
+
+ 9.9 Move charges at task migration
+        Charges associated with a task can be moved along with task migration.
+
+        (Shell-A)
+        #mkdir /cgroup/A
+        #echo $$ >/cgroup/A/tasks
+        run some programs which uses some amount of memory in /cgroup/A.
+
+        (Shell-B)
+        #mkdir /cgroup/B
+        #echo 1 >/cgroup/B/memory.move_charge_at_immigrate
+        #echo "pid of the program running in group A" >/cgroup/B/tasks
+
+        You can see charges have been moved by reading *.usage_in_bytes or
+        memory.stat of both A and B.
+        See 8.2 of Documentation/cgroups/memory.txt to see what value should be
+        written to move_charge_at_immigrate.