diff options
Diffstat (limited to 'Documentation/cgroups/blkio-controller.txt')
| -rw-r--r-- | Documentation/cgroups/blkio-controller.txt | 41 |
1 files changed, 22 insertions, 19 deletions
diff --git a/Documentation/cgroups/blkio-controller.txt b/Documentation/cgroups/blkio-controller.txt index 465351d..84f0a15 100644 --- a/Documentation/cgroups/blkio-controller.txt +++ b/Documentation/cgroups/blkio-controller.txt @@ -28,16 +28,19 @@ cgroups. Here is what you can do. - Enable group scheduling in CFQ CONFIG_CFQ_GROUP_IOSCHED=y -- Compile and boot into kernel and mount IO controller (blkio). +- Compile and boot into kernel and mount IO controller (blkio); see + cgroups.txt, Why are cgroups needed?. - mount -t cgroup -o blkio none /cgroup + 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 /cgroup/test1/ /cgroup/test2 + mkdir -p /sys/fs/cgroup/blkio/test1/ /sys/fs/cgroup/blkio/test2 - Set weights of group test1 and test2 - echo 1000 > /cgroup/test1/blkio.weight - echo 500 > /cgroup/test2/blkio.weight + 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. @@ -46,12 +49,12 @@ cgroups. Here is what you can do. echo 3 > /proc/sys/vm/drop_caches dd if=/mnt/sdb/zerofile1 of=/dev/null & - echo $! > /cgroup/test1/tasks - cat /cgroup/test1/tasks + echo $! > /sys/fs/cgroup/blkio/test1/tasks + cat /sys/fs/cgroup/blkio/test1/tasks dd if=/mnt/sdb/zerofile2 of=/dev/null & - echo $! > /cgroup/test2/tasks - cat /cgroup/test2/tasks + 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 @@ -68,13 +71,13 @@ Throttling/Upper Limit policy - Enable throttling in block layer CONFIG_BLK_DEV_THROTTLING=y -- Mount blkio controller - mount -t cgroup -o blkio none /cgroup/blkio +- 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 for policy is "<major>:<minor> <byes_per_second>". - echo "8:16 1048576" > /cgroup/blkio/blkio.read_bps_device + echo "8:16 1048576" > /sys/fs/cgroup/blkio/blkio.throttle.read_bps_device Above will put a limit of 1MB/second on reads happening for root group on device having major/minor number 8:16. @@ -87,7 +90,7 @@ Throttling/Upper Limit policy 1024+0 records out 4194304 bytes (4.2 MB) copied, 4.0001 s, 1.0 MB/s - Limits for writes can be put using blkio.write_bps_device file. + Limits for writes can be put using blkio.throttle.write_bps_device file. Hierarchical Cgroups ==================== @@ -108,7 +111,7 @@ Hierarchical Cgroups 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 @@ -149,7 +152,7 @@ Proportional weight policy files Following is the format. - #echo dev_maj:dev_minor weight > /path/to/cgroup/blkio.weight_device + # echo dev_maj:dev_minor weight > blkio.weight_device Configure weight=300 on /dev/sdb (8:16) in this cgroup # echo 8:16 300 > blkio.weight_device # cat blkio.weight_device @@ -283,28 +286,28 @@ Throttling/Upper limit policy files specified in bytes per second. Rules are per deivce. Following is the format. - echo "<major>:<minor> <rate_bytes_per_second>" > /cgrp/blkio.read_bps_device + echo "<major>:<minor> <rate_bytes_per_second>" > /cgrp/blkio.throttle.read_bps_device - blkio.throttle.write_bps_device - Specifies upper limit on WRITE rate to the device. IO rate is specified in bytes per second. Rules are per deivce. Following is the format. - echo "<major>:<minor> <rate_bytes_per_second>" > /cgrp/blkio.write_bps_device + echo "<major>:<minor> <rate_bytes_per_second>" > /cgrp/blkio.throttle.write_bps_device - blkio.throttle.read_iops_device - Specifies upper limit on READ rate from the device. IO rate is specified in IO per second. Rules are per deivce. Following is the format. - echo "<major>:<minor> <rate_io_per_second>" > /cgrp/blkio.read_iops_device + echo "<major>:<minor> <rate_io_per_second>" > /cgrp/blkio.throttle.read_iops_device - blkio.throttle.write_iops_device - Specifies upper limit on WRITE rate to the device. IO rate is specified in io per second. Rules are per deivce. Following is the format. - echo "<major>:<minor> <rate_io_per_second>" > /cgrp/blkio.write_iops_device + echo "<major>:<minor> <rate_io_per_second>" > /cgrp/blkio.throttle.write_iops_device Note: If both BW and IOPS rules are specified for a device, then IO is subjectd to both the constraints. |
