Documentation: cgroup: add documentation for net_cls cgroups.

This patch adds a new file, Documentation/cgroups/net_cls.txt, with info
about net_cls cgroups, and updates the 00-INDEX accordingly.

Signed-off-by: Rami Rosen <ramirose@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 36 insertions, 0 deletions

diff --git a/Documentation/cgroups/00-INDEX b/Documentation/cgroups/00-INDEX
index f5635a09c3f6..bc461b6425a7 100644
--- a/Documentation/cgroups/00-INDEX
+++ b/Documentation/cgroups/00-INDEX
@@ -18,6 +18,8 @@ memcg_test.txt
         - Memory Resource Controller; implementation details.
 memory.txt
         - Memory Resource Controller; design, accounting, interface, testing.
+net_cls.txt
+        - Network classifier cgroups details and usages.
 net_prio.txt
         - Network priority cgroups details and usages.
 resource_counter.txt
diff --git a/Documentation/cgroups/net_cls.txt b/Documentation/cgroups/net_cls.txt
new file mode 100644
index 000000000000..9face6bb578a
--- /dev/null
+++ b/Documentation/cgroups/net_cls.txt
@@ -0,0 +1,34 @@
+Network classifier cgroup
+-------------------------
+
+The Network classifier cgroup provides an interface to
+tag network packets with a class identifier (classid).
+
+The Traffic Controller (tc) can be used to assign
+different priorities to packets from different cgroups.
+
+Creating a net_cls cgroups instance creates a net_cls.classid file.
+This net_cls.classid value is initialized to 0.
+
+You can write hexadecimal values to net_cls.classid; the format for these
+values is 0xAAAABBBB; AAAA is the major handle number and BBBB
+is the minor handle number.
+Reading net_cls.classid yields a decimal result.
+
+Example:
+mkdir /sys/fs/cgroup/net_cls
+mount -t cgroup -onet_cls net_cls /sys/fs/cgroup/net_cls
+mkdir /sys/fs/cgroup/net_cls/0
+echo 0x100001 >  /sys/fs/cgroup/net_cls/0/net_cls.classid
+        - setting a 10:1 handle.
+
+cat /sys/fs/cgroup/net_cls/0/net_cls.classid
+1048577
+
+configuring tc:
+tc qdisc add dev eth0 root handle 10: htb
+
+tc class add dev eth0 parent 10: classid 10:1 htb rate 40mbit
+ - creating traffic class 10:1
+
+tc filter add dev eth0 parent 10: protocol ip prio 10 handle 1: cgroup