memcg: update document to mention that swapoff should be tested
Considering the recently found problem "memcg: fix refcnt handling at
swapoff", it's better to mention swapoff behavior in the memcg_test
document.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/cgroups/memcg_test.txt b/Documentation/cgroups/memcg_test.txt
index 19533f9..523a9c1 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: 2008/12/15
-Base Kernel Version: based on 2.6.28-rc8-mm.
+Last Updated: 2009/1/19
+Base Kernel Version: based on 2.6.29-rc2.
Because VM is getting complex (one of reasons is memcg...), memcg's behavior
is complex. This is a document for memcg's internal behavior.
@@ -340,3 +340,23 @@
# mount -t cgroup none /cgroup -t cpuset,memory,cpu,devices
and do task move, mkdir, rmdir etc...under this.
+
+ 9.7 swapoff.
+ Besides management of swap is one of complicated parts of memcg,
+ call path of swap-in at swapoff is not same as usual swap-in path..
+ It's worth to be tested explicitly.
+
+ For example, test like following is good.
+ (Shell-A)
+ # mount -t cgroup none /cgroup -t memory
+ # mkdir /cgroup/test
+ # echo 40M > /cgroup/test/memory.limit_in_bytes
+ # echo 0 > /cgroup/test/tasks
+ Run malloc(100M) program under this. You'll see 60M of swaps.
+ (Shell-B)
+ # move all tasks in /cgroup/test to /cgroup
+ # /sbin/swapoff -a
+ # rmdir /test/cgroup
+ # kill malloc task.
+
+ Of course, tmpfs v.s. swapoff test should be tested, too.