memcg: oom notifier

[safe/jmp/linux-2.6] / Documentation / cgroups / memory.txt

diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt
index 6cab1f2..eac22d3 100644 (file)
--- a/Documentation/cgroups/memory.txt
+++ b/Documentation/cgroups/memory.txt
@@ -184,6 +184,9 @@ limits on the root cgroup.
 
 Note2: When panic_on_oom is set to "2", the whole system will panic.
 
+When oom event notifier is registered, event will be delivered.
+(See oom_control section)
+
 2. Locking
 
 The memory controller uses the following hierarchy
@@ -488,7 +491,22 @@ threshold in any direction.
 
 It's applicable for root and non-root cgroup.
 
-10. TODO
+10. OOM Control
+
+Memory controler implements oom notifier using cgroup notification
+API (See cgroups.txt). It allows to register multiple oom notification
+delivery and gets notification when oom happens.
+
+To register a notifier, application need:
+ - create an eventfd using eventfd(2)
+ - open memory.oom_control file
+ - write string like "<event_fd> <memory.oom_control>" to cgroup.event_control
+
+Application will be notifier through eventfd when oom happens.
+OOM notification doesn't work for root cgroup.
+
+
+11. TODO
 
 1. Add support for accounting huge pages (as a separate controller)
 2. Make per-cgroup scanner reclaim not-shared pages first