[PATCH 0/2] Traffic control cgroups subsystem

[Ranjit Manomohan <ranjitm@google.com>]

This set of patches provides a simple resource controller (cgroup_tc) based
on the cgroups infrastructure to manage network traffic. The cgroup_tc resource
controller can be used to schedule and shape traffic belonging to the task(s)
in a particular cgroup.

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 from there to all packets associated with those sockets.

2) A new traffic control classifier (cls_cgroup) that can classify packets
    based on the tc_classid field in the packet to specific destination classes.

A simple 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 0x1234
mkdir -p /dev/cgroup
mount -t cgroup tc -otc /dev/cgroup
mkdir /dev/cgroup/file_transfer
echo 0x1234 > /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 1:2 htb rate 100mbit ceil 100mbit
tc filter add dev eth0 parent 1: protocol ip prio 1 handle 800 cgroup value 0x1234 classid 1:2

Signed-off-by: Ranjit Manomohan <ranjitm@google.com>

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