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authorJens Axboe <jaxboe@fusionio.com>2010-11-16 10:10:12 +0100
committerJens Axboe <jaxboe@fusionio.com>2010-11-16 10:10:12 +0100
commit5fbf85639287b6ea287f4f5e5e7e36608f0f60bd (patch)
tree608a51e6ee572dba94b43f1933e49ab88562e4c0 /Documentation
parenta02056349cdea2252cd2b21643ebf025e83a29f2 (diff)
parentbdc85df7a8417b9893443ff5520804699416b6f3 (diff)
downloadop-kernel-dev-5fbf85639287b6ea287f4f5e5e7e36608f0f60bd.zip
op-kernel-dev-5fbf85639287b6ea287f4f5e5e7e36608f0f60bd.tar.gz
Merge branch 'for-2.6.38/rc2-holder' into for-2.6.38/core
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/cgroups/blkio-controller.txt27
1 files changed, 27 insertions, 0 deletions
diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt
index d6da611..4ed7b5c 100644
--- a/Documentation/cgroups/blkio-controller.txt
+++ b/Documentation/cgroups/blkio-controller.txt
@@ -89,6 +89,33 @@ Throttling/Upper Limit policy
Limits for writes can be put using blkio.write_bps_device file.
+Hierarchical Cgroups
+====================
+- Currently none of the IO control policy supports hierarhical groups. But
+ cgroup interface does allow creation of hierarhical cgroups and internally
+ IO policies treat them as flat hierarchy.
+
+ So this patch will allow creation of cgroup hierarhcy but at the backend
+ everything will be treated as flat. So if somebody created a hierarchy like
+ as follows.
+
+ root
+ / \
+ test1 test2
+ |
+ test3
+
+ CFQ and throttling will practically treat all groups at same level.
+
+ pivot
+ / | \ \
+ root test1 test2 test3
+
+ Down the line we can implement hierarchical accounting/control support
+ and also introduce a new cgroup file "use_hierarchy" which will control
+ whether cgroup hierarchy is viewed as flat or hierarchical by the policy..
+ This is how memory controller also has implemented the things.
+
Various user visible config options
===================================
CONFIG_BLK_CGROUP
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