From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Tue, 9 Jul 2019 04:35:12 +0000 (-0700)
Subject: Merge branch 'for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
X-Git-Tag: tags/kvm-5.3-2~96
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=92c1d6522135050cb377a18cc6e30d08dfb87efb;p=users%2Fdwmw2%2Flinux.git
Merge branch 'for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
"Documentation updates and the addition of cgroup_parse_float() which
will be used by new controllers including blk-iocost"
* 'for-5.3' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
docs: cgroup-v1: convert docs to ReST and rename to *.rst
cgroup: Move cgroup_parse_float() implementation out of CONFIG_SYSFS
cgroup: add cgroup_parse_float()
---
92c1d6522135050cb377a18cc6e30d08dfb87efb
diff --cc Documentation/cgroup-v1/blkio-controller.rst
index d1a1b7bdd03ad,2c1b907afc147..fd3184537d238
--- a/Documentation/cgroup-v1/blkio-controller.rst
+++ b/Documentation/cgroup-v1/blkio-controller.rst
@@@ -15,15 -19,71 +17,18 @@@ level logical devices like device mappe
HOWTO
=====
-Proportional Weight division of bandwidth
------------------------------------------
-You can do a very simple testing of running two dd threads in two different
-cgroups. Here is what you can do.
-
-- Enable Block IO controller::
-
- CONFIG_BLK_CGROUP=y
-
-- Enable group scheduling in CFQ:
-
-
- CONFIG_CFQ_GROUP_IOSCHED=y
-
-- Compile and boot into kernel and mount IO controller (blkio); see
- cgroups.txt, Why are cgroups needed?.
-
- ::
-
- mount -t tmpfs cgroup_root /sys/fs/cgroup
- mkdir /sys/fs/cgroup/blkio
- mount -t cgroup -o blkio none /sys/fs/cgroup/blkio
-
-- Create two cgroups::
-
- mkdir -p /sys/fs/cgroup/blkio/test1/ /sys/fs/cgroup/blkio/test2
-
-- Set weights of group test1 and test2::
-
- echo 1000 > /sys/fs/cgroup/blkio/test1/blkio.weight
- echo 500 > /sys/fs/cgroup/blkio/test2/blkio.weight
-
-- Create two same size files (say 512MB each) on same disk (file1, file2) and
- launch two dd threads in different cgroup to read those files::
-
- sync
- echo 3 > /proc/sys/vm/drop_caches
-
- dd if=/mnt/sdb/zerofile1 of=/dev/null &
- echo $! > /sys/fs/cgroup/blkio/test1/tasks
- cat /sys/fs/cgroup/blkio/test1/tasks
-
- dd if=/mnt/sdb/zerofile2 of=/dev/null &
- echo $! > /sys/fs/cgroup/blkio/test2/tasks
- cat /sys/fs/cgroup/blkio/test2/tasks
-
-- At macro level, first dd should finish first. To get more precise data, keep
- on looking at (with the help of script), at blkio.disk_time and
- blkio.disk_sectors files of both test1 and test2 groups. This will tell how
- much disk time (in milliseconds), each group got and how many sectors each
- group dispatched to the disk. We provide fairness in terms of disk time, so
- ideally io.disk_time of cgroups should be in proportion to the weight.
-
Throttling/Upper Limit policy
-----------------------------
- - Enable Block IO controller
+ - Enable Block IO controller::
+
CONFIG_BLK_CGROUP=y
- - Enable throttling in block layer
+ - Enable throttling in block layer::
+
CONFIG_BLK_DEV_THROTTLING=y
- - Mount blkio controller (see cgroups.txt, Why are cgroups needed?)
+ - Mount blkio controller (see cgroups.txt, Why are cgroups needed?)::
+
mount -t cgroup -o blkio none /sys/fs/cgroup/blkio
- Specify a bandwidth rate on particular device for root group. The format