[RFC][PATCH 6/5] softlimit document

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

Sorry...6th patch.
==
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

Documentation for softlimit

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
 Documentation/cgroups/memory.txt |   19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

Index: mmotm-2.6.29-Mar10/Documentation/cgroups/memory.txt
===================================================================
--- mmotm-2.6.29-Mar10.orig/Documentation/cgroups/memory.txt
+++ mmotm-2.6.29-Mar10/Documentation/cgroups/memory.txt
@@ -322,6 +322,25 @@ will be charged as a new owner of it.
   - a cgroup which uses hierarchy and it has child cgroup.
   - a cgroup which uses hierarchy and not the root of hierarchy.
 
+5.4 softlimit
+  Memory cgroup supports softlimit and has 2 params for control.
+    - memory.softlimit_in_bytes
+	- softlimit to this cgroup.
+    - memory.softlimit_priority.
+	- priority of this cgroup at softlimit reclaim.
+	  Allowed priority level is 3-0 and 3 is the lowest.
+	  If 0, this cgroup will not be target of softlimit.
+
+  At memory shortage of the system (or local node/zone), softlimit helps
+  kswapd(), a global memory recalim kernel thread, and inform victim cgroup
+  to be shrinked to kswapd.
+
+  Victim selection logic:
+  The kernel searches from the lowest priroty(3) up to the highest(1).
+  If it find a cgroup witch has memory larger than softlimit, steal memory
+  from it.
+  If multiple cgroups are on the same priority, each cgroup wil be a
+  victim in turn.
 
 6. Hierarchy support