LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
To: Vivek Goyal <vgoyal@redhat.com>, Jens Axboe <axboe@kernel.dk>
Cc: Gui Jianfeng <guijianfeng@cn.fujitsu.com>,
	linux kernel mailing list <linux-kernel@vger.kernel.org>,
	Corrado Zoccolo <czoccolo@gmail.com>,
	Chad Talbott <ctalbott@google.com>,
	Nauman Rafique <nauman@google.com>,
	Divyesh Shah <dpshah@google.com>,
	jmoyer@redhat.com, Shaohua Li <shaohua.li@intel.com>
Subject: [PATCH 6/6 v3] blkio-cgroup: Document for blkio.use_hierarchy interface
Date: Mon, 27 Dec 2010 16:51:20 +0800	[thread overview]
Message-ID: <4D185388.4080104@cn.fujitsu.com> (raw)
In-Reply-To: <4D180ECE.4000305@cn.fujitsu.com>

Document for blkio.use_hierarchy interface

Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
---
 Documentation/cgroups/blkio-controller.txt |   70 ++++++++++++++++++++--------
 1 files changed, 51 insertions(+), 19 deletions(-)

diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt
index 4ed7b5c..bd01d6c 100644
--- a/Documentation/cgroups/blkio-controller.txt
+++ b/Documentation/cgroups/blkio-controller.txt
@@ -91,30 +91,51 @@ 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 blkio.use_hierarchy is disabled in all CGroups, CFQ 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 blkio.use_hierarchy is enabled in Grp1 and Grp3, CFQ will treat groups and tasks as the
+  same view in CGroup hierarchy, it looks as follows.
+
+
+			     Pivot tree
+			    /    |    \
+			  Root  Grp1  Grp2
+			  /     /  \
+		       tsk1   Grp3 tsk2
+
+  Root, Grp1 and Grp2 are treated at the same level under Pivot tree. tsk1 stays under Root.
+  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
+
+  Note1: Regardless of the use_hierarchy setting in Root group, Root group is always put onto
+  Pivot tree.
+
+  Note2: Currently, "blkio.use_hierarchy" only effects proportional bandwidth division. For
+  Throttling logic, it still continue to treat everything as flat.
 
 Various user visible config options
 ===================================
@@ -169,6 +190,17 @@ 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.
+	  You can set this interface only if there isn't any child CGroup under
+	  this CGroup. If one CGroup's blkio.use_hierarchy is set, the created
+	  children will inherit it. it's not allowed to unset it in children.
+	  The default mode in Root CGroup is flat.
+	  blkio.use_hierarchy only works for proportional bandwidth division
+	  as of today and doesn't have any effect on throttling logic.
+
 - 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








  parent reply	other threads:[~2010-12-27  8:51 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <4D180ECE.4000305@cn.fujitsu.com>
2010-12-27  8:50 ` [PATCH 1/6 v3] cfq-iosched: Introduce cfq_entity for CFQ queue Gui Jianfeng
2010-12-27  8:50 ` [PATCH 2/6 v3] cfq-iosched: Introduce cfq_entity for CFQ group Gui Jianfeng
2011-01-18 21:20   ` Vivek Goyal
2011-01-19  1:25     ` Gui Jianfeng
2011-01-23  2:15     ` Gui Jianfeng
2010-12-27  8:51 ` [PATCH 3/6 v3] cfq-iosched: Introduce vdisktime and io weight for CFQ queue Gui Jianfeng
2010-12-28  2:50   ` Shaohua Li
2010-12-28  3:59     ` Gui Jianfeng
2010-12-28  6:03       ` Shaohua Li
2010-12-28  6:59         ` Gui Jianfeng
2011-01-19 22:58   ` Vivek Goyal
2011-01-20  3:58     ` Gui Jianfeng
2011-01-20 11:09       ` Vivek Goyal
2011-01-24  4:45         ` Gui Jianfeng
2011-01-24 18:51           ` Vivek Goyal
2010-12-27  8:51 ` [PATCH 4/6 v3] cfq-iosched: Extract some common code of service tree handling for CFQ queue and CFQ group Gui Jianfeng
2010-12-27  8:51 ` [PATCH 5/6 v3] cfq-iosched: CFQ group hierarchical scheduling and use_hierarchy interface Gui Jianfeng
2011-01-24 22:52   ` Vivek Goyal
2010-12-27  8:51 ` Gui Jianfeng [this message]
2011-01-18 20:27   ` [PATCH 6/6 v3] blkio-cgroup: Document for blkio.use_hierarchy interface Vivek Goyal
2011-01-19  1:20     ` Gui Jianfeng

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=4D185388.4080104@cn.fujitsu.com \
    --to=guijianfeng@cn.fujitsu.com \
    --cc=axboe@kernel.dk \
    --cc=ctalbott@google.com \
    --cc=czoccolo@gmail.com \
    --cc=dpshah@google.com \
    --cc=jmoyer@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=nauman@google.com \
    --cc=shaohua.li@intel.com \
    --cc=vgoyal@redhat.com \
    --subject='Re: [PATCH 6/6 v3] blkio-cgroup: Document for blkio.use_hierarchy interface' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).