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authorLinus Torvalds <torvalds@linux-foundation.org>2011-01-13 10:45:01 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-01-13 10:45:01 -0800
commit275220f0fcff1adf28a717076e00f575edf05fda (patch)
treed249bccc80c64443dab211639050c4fb14332648 /Documentation
parentfe3c560b8a22cb28e54fe8950abef38e88d75831 (diff)
parent81c5e2ae33c4b19e53966b427e33646bf6811830 (diff)
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Merge branch 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-block
* 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-block: (43 commits) block: ensure that completion error gets properly traced blktrace: add missing probe argument to block_bio_complete block cfq: don't use atomic_t for cfq_group block cfq: don't use atomic_t for cfq_queue block: trace event block fix unassigned field block: add internal hd part table references block: fix accounting bug on cross partition merges kref: add kref_test_and_get bio-integrity: mark kintegrityd_wq highpri and CPU intensive block: make kblockd_workqueue smarter Revert "sd: implement sd_check_events()" block: Clean up exit_io_context() source code. Fix compile warnings due to missing removal of a 'ret' variable fs/block: type signature of major_to_index(int) to major_to_index(unsigned) block: convert !IS_ERR(p) && p to !IS_ERR_NOR_NULL(p) cfq-iosched: don't check cfqg in choose_service_tree() fs/splice: Pull buf->ops->confirm() from splice_from_pipe actors cdrom: export cdrom_check_events() sd: implement sd_check_events() sr: implement sr_check_events() ...
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