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    Subject[PATCH 0/6] Multi-hierarchy Process Containers

    This is an update to my generic containers patch. The major change is
    support for multiple hierarchies of containers (up to a limit
    specified at build time).

    - The mount options passed when mounting a container filesystem
    indicate the set of controllers/subsystems that are wanted in the
    hierarchy - e.g. "mount -t container -o cpuset,numtasks container /foo"

    - Default is to try to mount all subsystems

    - if a hierarchy with the requested set of subsystems already exists
    then its superblock is reused

    - otherwise (as long as all the requested subsystems are currently not
    in use in any hierarchy) a new hierarchy is created.

    - hierarchies with more than one container (i.e. with any children of
    the root container) persist even when unmounted;

    - /proc/containers shows current hierarchy/subsystem details

    - /proc/<pid>/container shows one line for each active hierarchy

    Other changes include:

    - ported to 2.6.19-rc5

    - per-subsystem/per-container state is no longer just a void * - it
    has some state maintained by the container framework (to handle
    moving subsystems in and out of hierarchies when they are created/released)

    Note that this hasn't yet undergone intensive testing following the
    multi-hierarchy introduction, but I wanted to get the basic idea out
    for comments.

    TODOs include:

    - figuring out a nice way to handle release notifications now that
    there are multiple hierarchies


    There have recently been various proposals floating around for
    resource management/accounting subsystems in the kernel, including
    Res Groups, User BeanCounters and others. These all need the basic
    abstraction of being able to group together multiple processes in an
    aggregate, in order to track/limit the resources permitted to those
    processes, and all implement this grouping in different ways.

    Already existing in the kernel is the cpuset subsystem; this has a
    process grouping mechanism that is mature, tested, and well documented
    (particularly with regards to synchronization rules).

    This patchset extracts the process grouping code from cpusets into a
    generic container system, and makes the cpusets code a client of
    the container system.

    It also provides a very simple additional container subsystem to do
    per-container CPU usage accounting; this is primarily to demonstrate
    use of the container subsystem API, but is useful in its own right.

    The change is implemented in five stages plus an additional example patch:

    1) extract the process grouping code from cpusets into a standalone system

    2) remove the process grouping code from cpusets and hook into the
    container system

    3) convert the container system to present a generic multi-hierarchy
    API, and make cpusets a client of that API

    4) add a simple CPU accounting container subsystem as an example

    5) add support for fork/exit callbacks iff some subsystem is interested in them

    6) example of implementing ResGroups and its numtasks controller over
    generic containers - not intended to be applied with this patch set

    The intention is that the various resource management efforts can also
    become container clients, with the result that:

    - the userspace APIs are (somewhat) normalised

    - it's easier to test out e.g. the ResGroups CPU controller in
    conjunction with the UBC memory controller

    - the additional kernel footprint of any of the competing resource
    management systems is substantially reduced, since it doesn't need
    to provide process grouping/containment, hence improving their
    chances of getting into the kernel

    Signed-off-by: Paul Menage <>
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      Last update: 2006-11-17 20:17    [W:0.051 / U:0.064 seconds]
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