[PATCH 0/0] Traffic control cgroups subsystem

[Ranjit Manomohan <ranjitm@google.com>]

[Take 4] incorporated additional comments from Patrick McHardy

This patch 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 will be used for classifying packets at the link layer.

2) A new traffic control classifier (cls_cgroup) 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 arbitrary unique
# classid of 0x1234 - this will be used later to direct packets.
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 1:10 htb rate 100mbit ceil 100mbit
tc filter add dev eth0 parent 1: handle 800 protocol ip prio 1 cgroup value 0x1234 classid 1:10

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

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