lkml.org 
[lkml]   [2006]   [Apr]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Date
    Subject[RFC][PATCH 9/9] CPU controller - Documents how to use the controller
    9/9: ckrm_cpu_docs

    Documents how to use the CPU controller

    Signed-off-by: MAEDA Naoaki <maeda.naoaki@jp.fujitsu.com>
    Signed-off-by: Kurosawa Takahiro <kurosawa@valinux.co.jp>

    Documentation/ckrm/cpurc | 70 +++++++++++++++++++++++++++++++++++++++++++++++
    1 files changed, 70 insertions(+)

    Index: linux-2.6.17-rc2/Documentation/ckrm/cpurc
    ===================================================================
    --- /dev/null
    +++ linux-2.6.17-rc2/Documentation/ckrm/cpurc
    @@ -0,0 +1,71 @@
    +Introduction
    +------------
    +
    +CPU resource controller enables user/sysadmin to control CPU time
    +percentage of tasks in a class. It controls time_slice of tasks based on
    +the feedback of difference between the target value and the current usage
    +in order to control the percentage of the CPU usage to the target value.
    +
    +Installation
    +------------
    +
    +1. Configure "CPU Resource Controller" under CKRM. Currently, this cannot be
    +configured as a module.
    +
    +2. Reboot the system with the new kernel.
    +
    +3. Verify that the CPU resource controller is present by reading
    +the file /config/ckrm/shares (should show a line with res=cpu).
    +
    +Assigning shares
    +----------------
    +
    +Follows the general approach of setting shares for a class in CKRM.
    +
    +# echo "res=cpu,min_shares=val" > shares
    +
    +sets the min_shares of a class.
    +
    +The CPU resource controller calculates an effective min_shares in percent
    +for each class. Following is an example of class/min_shares settings
    +and each effective min_shares.
    +
    + /
    + effective_min_shares
    + = 100% - 50% - 30%
    + = 20%
    + +---------------+---------------+
    + /A min_shares=50% /B min_shares=30%
    + effective_min_shares effective_min_shares
    + = 50% - 10% - 25% = 30% - 0%
    + = 15% = 30%
    ++---------------+---------------+
    +/C min_shares=20% /D min_shares=50%
    +effective_min_shares effective_min_shares
    += 20% of 50% - 0% = 10% = 50% of 50% - 0 %
    += 10% = 25%
    +
    +If the min_shares in the class /A is changed 50% to 40% in the above
    +example, the effective_min_shares of the class /A, /C and /D are automatically
    +changed to 12%, 8% and 20% respectively.
    +
    +Although the child_shares_divisor can be changed, the effective_min_shares is
    +always calculated in percent.
    +
    +Note that the CPU resource controller doesn't support the limit, so assigning
    +the limit for "res=cpu" will have no effect.
    +
    +Monitoring
    +----------
    +
    +stats file shows the effective min_shares and the current cpu usage of a class
    +in percentage.
    +
    +# cat stats
    +cpu:effective_min_shares=50, load=40
    +
    +That means the effective min_shares of the class is 50% and the current load
    +average of the class is 40%.
    +
    +Since the tasks in the class do not always try to consume CPU, the load could be
    +less or greater than the effective_min_shares. Both cases are normal.
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/
    \
     
     \ /
      Last update: 2006-04-21 04:32    [W:4.186 / U:0.012 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site