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    Subject[RFC] Revised CKRM release
    The Class-based Resource Management project is happy to release the
    first bits of a working prototype following a major revision of its
    interface and internal organization.

    The basic concepts and motivation of CKRM remain the same as described
    in the overview at Privileged users can define
    classes consisting of groups of kernel objects (currently tasks and
    sockets) and specify shares for these classes. Resource controllers,
    which are independent of each other, can regulate and monitor the
    resources consumed by classes e.g the CPU controller will control the
    CPU time received by a class etc. Optional classification engines,
    implemented as kernel modules, can assist in the automatic
    classification of the kernel objects (tasks/sockets currently) into

    New in this release are the following:

    1) A filesystem-based user interface, proposed by Rik van Riel, to
    replace the system call interface in the previous prototype.

    2) A hierarchy of classes can now be created so that a class (created
    per user, say) can subdivide its share allocation among its children
    classes (created one per application type), independent of its peer
    classes (other users).

    3) A newly introduced notion of a classtype which defines what kind of
    kernel objects are being grouped into a class for regulation and
    monitoring. Grouping tasks, into the taskclass classtype, is the most
    commonly expected use. The prototype also implements the socketclass
    classtype, useful for controlling groups of sockets.

    4) Resource controllers are now explicitly associated with a
    classtype. The CPU memory and I/O controllers (not yet implemented)
    will operate on taskclasses while the multiple accept queue controller
    operates on socketclasses.

    5) A functional socketaq network controller which regulates the number
    of accepted TCP connections for groups of listening sockets.

    The newly implemented features have been described at some length in a
    document posted on lkml a while back and available at

    A revised description and update of the project webpages is in
    progress. The patches will be posted individually and are described
    below. They are also available on

    Comments/feedback welcome. If this looks interesting, please consider
    joining the mailing list.

    -- Hubertus Franke, Shailabh Nagar, Chandra Seetharaman, Vivek Kashyap

    CKRM Patches overview

    All patches against 2.6.5.


    Core code of ckrm which glues the interface (rcfs), resource
    controllers (rc's) and classification engines (ce's) into the


    Resource control filesystem (rcfs) forming the user interface to CKRM.


    Creates the taskclass classtype for use by resource controllers which
    operate on groups of tasks. The CPU, memory and I/O resource
    controllers will operate on taskclasses when their rewrite/port to the
    new API is complete. The patch includes the rcfs interface to


    A simple resource controller that limits the number of tasks that can
    be forked within a taskclass. Implemented mainly to serve as a
    prototype for resource controller writers. Modifications to
    kernel/exit.c and kernel/fork.c which should strictly be part of this
    patch are included in the 00-core.ckrm-E12.patch.


    Creates the socketclass classtype, alongwith its rcfs interface, for
    use by resource controllers which operate on groups of sockets.


    A resource controller that controls the number of accepted TCP
    connections. It is CKRM's first real controller. Changes include
    modifications to the TCP stack to implement multiple accept queues.


    Two classification engines (CE) to assist in automatic classification
    of tasks and sockets. The first one, rbce, implements a rule-based
    classification engine which is generic enough for most users. The
    second, called crbce, is a variant of rbce which additionally provides
    information on significant kernel events (where a task/socket could
    get reclassified) to userspace as well as reports per-process wait
    times for cpu, memory, io etc. Such information can be used by user
    level tools to reclassify tasks to new classes, change class shares
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