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    Subject[PATCH 1/2] range-bw documentation
    This is the patch file for range-bw documentation

    From: Dong-Jae Kang <> or <>

    Range-BW is an I/O controller supports the process group-based range bandwidth
    according to the priority or importance of the group.
    Range bandwidth means the predicable I/O bandwidth with minimum and
    maximum value
    defined by administrator.

    Signed-off-by: Dong-Jae Kang <>
    Signed-off-by: Chei-Yol Kim <>


    diff -urN linux-2.6.29-orig/Documentation/device-mapper/range-bw.txt
    --- linux-2.6.29-orig/Documentation/device-mapper/range-bw.txt 1970-01-01
    09:00:00.000000000 +0900
    +++ linux-2.6.29-patch/Documentation/device-mapper/range-bw.txt 2009-05-04
    15:38:02.000000000 +0900
    @@ -0,0 +1,91 @@
    +Range-BW I/O controller by Dong-Jae Kang <>
    +1. Introduction
    +The design of Range-BW is related with three another parts, Cgroup,
    bio-cgroup (or blkio-cgroup) and dm-ioband
    +and it was implemented as an additional controller for dm-ioband.
    +Cgroup framework is used to support process grouping mechanism and
    bio-cgroup is used to control delayed I/O or
    +non-direct I/O. Finally, dm-ioband is a kind of I/O controller
    allowing the proportional I/O bandwidth
    +to process groups based on its priority.
    +The supposed controller supports the process group-based range
    bandwidth according to the priority or
    +importance of the group. Range bandwidth means the predicable I/O
    bandwidth with minimum and maximum value
    +defined by administrator.
    +Minimum I/O bandwidth should be guaranteed for stable performance or
    reliability of specific service
    +and I/O bandwidth over maximum should be throttled to protect the
    limited I/O resource from over-provisioning
    +in unnecessary usage or to reserve the I/O bandwidth for another use.
    +So, Range-BW was implemented to include the two concepts,
    guaranteeing of minimum I/O requirement
    +and limitation of unnecessary bandwidth depending on its priority.
    +And it was implemented as device mapper driver such like dm-ioband.
    +So, it is independent of the underlying specific I/O scheduler, for
    example, CFQ, AS, NOOP, deadline and so on.
    +Range-BW has two kinds of operation modes, min-max and max mode.
    Min-max mode is to supports guaranteeing
    +the minimum I/O requirement and limitation of unnecessary I/O
    bandwidth at the same time.
    +And max mode is to support only limitation. So in case of min-max
    mode, you need to configure min-bw
    +and max-bw values and in case of max mode, configure only max-bw.
    +* Attention
    +Range-BW supports the predicable I/O bandwidth, but it should be
    configured in the scope of total I/O bandwidth
    +of the I/O system to guarantee the minimum I/O requirement. For
    example, if total I/O bandwidth is 40Mbytes/sec,
    +the summary of I/O bandwidth configured in each process group should
    be equal or smaller than 40Mbytes/sec.
    +So, we need to check total I/O bandwidth before set it up.
    +2. Setup and Installation
    +This part is same with dm-ioband,
    ../../Documentation/device-mapper/ioband.txt or
    +You must first install the appropriate bio-cgroup and dm-ioband
    patches before using range-bw patch.
    +3. Usage
    +It is very useful to refer the documentation for dm-ioband in
    ../../Documentation/device-mapper/ioband.txt or
    +, because Range-BW
    follows the basic semantics of dm-ioband.
    +This example is for min-max mode.
    +# mount the cgroup
    +mount -t cgroup -o bio none /root/cgroup/bio
    +# create the process groups (3 groups)
    +mkdir /root/cgroup/bio/bgroup1
    +mkdir /root/cgroup/bio/bgroup2
    +mkdir /root/cgroup/bio/bgroup3
    +# create the ioband device ( name : ioband1 )
    +echo "0 $(blockdev --getsize /dev/sdb2) ioband /dev/sdb2 1 0 0 none
    +range-bw 0 :0" | dmsetup create ioband1
    +: device name (/dev/sdb2) should be modified depending on your system
    +# init ioband device ( type and policy )
    +dmsetup message ioband1 0 type cgroup
    +dmsetup message ioband1 0 policy range-bw
    +# attach the groups to the ioband device
    +dmsetup message ioband1 0 attach 2
    +dmsetup message ioband1 0 attach 3
    +dmsetup message ioband1 0 attach 4
    +: group number can be referred in /root/cgroup/bio/bgroup1/
    +# allocate the values ( min-bw and max-bw ) : XXX Kbytes
    +: the sum of minimum I/O bandwidth in each group should be equal or
    smaller than total bandwidth
    + to be supported by your system
    +# range : about 100~500 Kbytes
    +dmsetup message ioband1 0 min-bw 2:100
    +dmsetup message ioband1 0 max-bw 2:500
    +# range : about 700~1000 Kbytes
    +dmsetup message ioband1 0 min-bw 3:700
    +dmsetup message ioband1 0 max-bw 3:1000
    +# range : about 50~60Mbytes
    +dmsetup message ioband1 0 min-bw 4:50000
    +dmsetup message ioband1 0 max-bw 4:60000
    +You can confirm the configuration of range-bw by using this command :
    +[root@localhost range-bw]# dmsetup table --target ioband
    +ioband1: 0 305235000 ioband 8:18 1 4 128 cgroup range-bw 16384 :0
    2:100:500 3:700:1000 4:30000:60000
    Best Regards,
    Dong-Jae Kang

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