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-rw-r--r--Documentation/cgroups/blkio-controller.txt29
1 files changed, 16 insertions, 13 deletions
diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt
index 465351d4cf85..b1b1bfadc9c0 100644
--- a/Documentation/cgroups/blkio-controller.txt
+++ b/Documentation/cgroups/blkio-controller.txt
@@ -28,16 +28,19 @@ cgroups. Here is what you can do.
28- Enable group scheduling in CFQ 28- Enable group scheduling in CFQ
29 CONFIG_CFQ_GROUP_IOSCHED=y 29 CONFIG_CFQ_GROUP_IOSCHED=y
30 30
31- Compile and boot into kernel and mount IO controller (blkio). 31- Compile and boot into kernel and mount IO controller (blkio); see
32 cgroups.txt, Why are cgroups needed?.
32 33
33 mount -t cgroup -o blkio none /cgroup 34 mount -t tmpfs cgroup_root /sys/fs/cgroup
35 mkdir /sys/fs/cgroup/blkio
36 mount -t cgroup -o blkio none /sys/fs/cgroup/blkio
34 37
35- Create two cgroups 38- Create two cgroups
36 mkdir -p /cgroup/test1/ /cgroup/test2 39 mkdir -p /sys/fs/cgroup/blkio/test1/ /sys/fs/cgroup/blkio/test2
37 40
38- Set weights of group test1 and test2 41- Set weights of group test1 and test2
39 echo 1000 > /cgroup/test1/blkio.weight 42 echo 1000 > /sys/fs/cgroup/blkio/test1/blkio.weight
40 echo 500 > /cgroup/test2/blkio.weight 43 echo 500 > /sys/fs/cgroup/blkio/test2/blkio.weight
41 44
42- Create two same size files (say 512MB each) on same disk (file1, file2) and 45- Create two same size files (say 512MB each) on same disk (file1, file2) and
43 launch two dd threads in different cgroup to read those files. 46 launch two dd threads in different cgroup to read those files.
@@ -46,12 +49,12 @@ cgroups. Here is what you can do.
46 echo 3 > /proc/sys/vm/drop_caches 49 echo 3 > /proc/sys/vm/drop_caches
47 50
48 dd if=/mnt/sdb/zerofile1 of=/dev/null & 51 dd if=/mnt/sdb/zerofile1 of=/dev/null &
49 echo $! > /cgroup/test1/tasks 52 echo $! > /sys/fs/cgroup/blkio/test1/tasks
50 cat /cgroup/test1/tasks 53 cat /sys/fs/cgroup/blkio/test1/tasks
51 54
52 dd if=/mnt/sdb/zerofile2 of=/dev/null & 55 dd if=/mnt/sdb/zerofile2 of=/dev/null &
53 echo $! > /cgroup/test2/tasks 56 echo $! > /sys/fs/cgroup/blkio/test2/tasks
54 cat /cgroup/test2/tasks 57 cat /sys/fs/cgroup/blkio/test2/tasks
55 58
56- At macro level, first dd should finish first. To get more precise data, keep 59- At macro level, first dd should finish first. To get more precise data, keep
57 on looking at (with the help of script), at blkio.disk_time and 60 on looking at (with the help of script), at blkio.disk_time and
@@ -68,13 +71,13 @@ Throttling/Upper Limit policy
68- Enable throttling in block layer 71- Enable throttling in block layer
69 CONFIG_BLK_DEV_THROTTLING=y 72 CONFIG_BLK_DEV_THROTTLING=y
70 73
71- Mount blkio controller 74- Mount blkio controller (see cgroups.txt, Why are cgroups needed?)
72 mount -t cgroup -o blkio none /cgroup/blkio 75 mount -t cgroup -o blkio none /sys/fs/cgroup/blkio
73 76
74- Specify a bandwidth rate on particular device for root group. The format 77- Specify a bandwidth rate on particular device for root group. The format
75 for policy is "<major>:<minor> <byes_per_second>". 78 for policy is "<major>:<minor> <byes_per_second>".
76 79
77 echo "8:16 1048576" > /cgroup/blkio/blkio.read_bps_device 80 echo "8:16 1048576" > /sys/fs/cgroup/blkio/blkio.read_bps_device
78 81
79 Above will put a limit of 1MB/second on reads happening for root group 82 Above will put a limit of 1MB/second on reads happening for root group
80 on device having major/minor number 8:16. 83 on device having major/minor number 8:16.
@@ -149,7 +152,7 @@ Proportional weight policy files
149 152
150 Following is the format. 153 Following is the format.
151 154
152 #echo dev_maj:dev_minor weight > /path/to/cgroup/blkio.weight_device 155 # echo dev_maj:dev_minor weight > blkio.weight_device
153 Configure weight=300 on /dev/sdb (8:16) in this cgroup 156 Configure weight=300 on /dev/sdb (8:16) in this cgroup
154 # echo 8:16 300 > blkio.weight_device 157 # echo 8:16 300 > blkio.weight_device
155 # cat blkio.weight_device 158 # cat blkio.weight_device