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    SubjectRe: [PATCH] Traffic control cgroups subsystem
    * Ranjit Manomohan <ranjitm@google.com> 2008-07-22 10:44
    > The implementation consists of two parts:
    >
    > 1) A resource controller (cgroup_tc) that is used to associate packets from
    > a particular task belonging to a cgroup with a traffic control class id (
    > tc_classid). This tc_classid is propagated to all sockets created by
    > tasks
    > in the cgroup and will be used for classifying packets at the link layer.
    >
    > 2) A modified traffic control classifier (cls_flow) that can classify
    > packets
    > based on the tc_classid field in the socket to specific destination
    > classes.
    >
    > An example of the use of this resource controller would be to limit
    > the traffic from all tasks from a file_server cgroup to 100Mbps. We could
    > achieve this by doing:
    >
    > # make a cgroup of file transfer processes and assign it a uniqe classid
    > # of 0x10 - this will be used lated to direct packets.
    > mkdir -p /dev/cgroup
    > mount -t cgroup tc -otc /dev/cgroup
    > mkdir /dev/cgroup/file_transfer
    > echo 0x10 > /dev/cgroup/file_transfer/tc.classid
    > echo $PID_OF_FILE_XFER_PROCESS > /dev/cgroup/file_transfer/tasks
    >
    > # Now create a HTB class that rate limits traffic to 100mbits and attach
    > # a filter to direct all traffic from cgroup file_transfer to this new
    > class.
    > tc qdisc add dev eth0 root handle 1: htb
    > tc class add dev eth0 parent 1: classid 1:10 htb rate 100mbit ceil 100mbit
    > tc filter add dev eth0 parent 1: handle 800 protocol ip prio 1 flow map key
    > cgroup-classid baseclass 1:10

    It might have been easier to simply write a classifier which maps pids
    to classes. The interface could be as simple as two nested attributes,
    ADD_MAPS, REMOVE_MAPS which both take lists of pid->class mappings to
    either add or remove from the classifier.

    I have been working on this over the past 2 weeks, it includes the
    classifier as just stated, a cgroup module which sends notifications
    about events as netlink messages and a daemon which creates qdiscs,
    classes and filters on the fly according to the configured distribution.
    It works both ingress (with some tricks) and egress.

    IMHO, there is no point in a cgroup interface if the user has to create
    qdiscs, classes and filters manually anyway.


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