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Date: Mon, 13 Dec 2010 09:45:22 +0800 From: Gui Jianfeng <guijianfeng@...fujitsu.com> To: Jens Axboe <axboe@...nel.dk>, Vivek Goyal <vgoyal@...hat.com> CC: Gui Jianfeng <guijianfeng@...fujitsu.com>, Corrado Zoccolo <czoccolo@...il.com>, Chad Talbott <ctalbott@...gle.com>, Nauman Rafique <nauman@...gle.com>, Divyesh Shah <dpshah@...gle.com>, linux kernel mailing list <linux-kernel@...r.kernel.org> Subject: [PATCH 8/8] blkio-cgroup: Document for blkio.use_hierarchy. Document for blkio.use_hierarchy. Signed-off-by: Gui Jianfeng <guijianfeng@...fujitsu.com> --- Documentation/cgroups/blkio-controller.txt | 58 +++++++++++++++++++--------- 1 files changed, 39 insertions(+), 19 deletions(-) diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt index 4ed7b5c..9c6dc9e 100644 --- a/Documentation/cgroups/blkio-controller.txt +++ b/Documentation/cgroups/blkio-controller.txt @@ -91,30 +91,44 @@ Throttling/Upper Limit policy 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. +- Cgroup interface allows creation of hierarchical cgroups. Currently, + internally IO policies are able to treat them as flat hierarchy or + hierarchical hierarchy. Both hierarchical bandwidth division and flat + bandwidth division are supported. "blkio.use_hierarchy" can be used to + switch between flat mode and hierarchical mode. - 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. + Consider the following CGroup hierarchy: - root - / \ - test1 test2 - | - test3 + Root + / | \ + Grp1 Grp2 tsk1 + / \ + Grp3 tsk2 - CFQ and throttling will practically treat all groups at same level. + If flat mode is enabled, CFQ and throttling will practically treat all + groups at the same level. - pivot - / | \ \ - root test1 test2 test3 + Pivot tree + / | | \ + Root Grp1 Grp2 Grp3 + / | + tsk1 tsk2 - 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. + If hierarchical mode is enabled, CFQ will treat groups and tasks as the same + view in CGroup hierarchy. + + Root + / | \ + Grp1 Grp2 tsk1 + / \ + Grp3 tsk2 + + Grp1, Grp2 and tsk1 are treated at the same level under Root group. Grp3 and + tsk2 are treated at the same level under Grp1. Below is the mapping between + task io priority and io weight: + + prio 0 1 2 3 4 5 6 7 + weight 1000 868 740 612 484 356 228 100 Various user visible config options =================================== @@ -169,6 +183,12 @@ Proportional weight policy files dev weight 8:16 300 +- blkio.use_hierarchy + - Switch between hierarchical mode and flat mode as stated above. + blkio.use_hierarchy == 1 means hierarchical mode is enabled. + blkio.use_hierarchy == 0 means flat mode is enabled. + The default mode is flat mode. + - blkio.time - disk time allocated to cgroup per device in milliseconds. First two fields specify the major and minor number of the device and -- 1.6.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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