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    Subject[PATCH 0/7] CPU controller - V1
    This patch is an attempt to provide some minimal CPU controller for resource
    management purpose. Although we have seen several proposals for one before,
    none has gained acceptance yet. For ex: http://lkml.org/lkml/2006/8/4/137
    summarizes the feedback received against the last CPU controller posted by
    Fujitsu folks.

    This is V1 of the patch posted at http://lkml.org/lkml/2006/8/4/6
    and has been tested against 2.6.18-rc3.

    Change since last version:

    - Basic task-group aware SMP load balancing, based on SMP nice
    mechanism

    Still on my todo list:

    - Cleanup so that !CONFIG_CPUMETER has zero impact
    - Better timeslice management, so that bursty workloads
    can be handled well. I have some ideas (for ex: don't
    switch active/expired arrays as soon as active
    array becomes empty) which I would like to experiment
    with a bit before sending a patch for this
    - Better SMP load balancing. I feel that some feedback
    about how much bandwidth a task-group is actually
    getting (compared to its quota) can be included in
    runqueue pressure calculations.

    Salient design points of this patch:

    - Each task-group gets its own runqueue on every cpu.

    - In addition, there is an active and expired array of
    task-groups themselves. Task-groups who have expired their
    quota are put into expired array.

    - Task-groups have priorities. Priority of a task-group is the
    same as the priority of the highest-priority runnable task it
    has. This I feel will retain interactiveness of the system
    as it is today.

    - Scheduling the next task involves picking highest priority task-group
    from active array first and then picking highest-priority task
    within it. Both steps are O(1).

    - Token are assigned to task-groups based on their assigned
    quota. Once they run out of tokens, the task-group is put
    in an expired array. Array switch happens when active array
    is empty.

    - SMP load-balancing is accomplished on the lines of smpnice.

    - Although the algorithm is very simple, it perhaps needs more
    refinement to handle different cases. Especially I
    feel task-groups which are idle most of the time and
    experience bursts once in a while will need to be handled
    better than this simple scheme.

    Ingo/Nick,
    Would request your inputs as before.


    --
    Regards,
    vatsa
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