X-Git-Url: http://pilppa.org/gitweb/gitweb.cgi?a=blobdiff_plain;f=Documentation%2Fnetworking%2Fmultiqueue.txt;h=4caa0e314cc2929f1991b05bc8b91cb634b86635;hb=85e39035ca381846b031690f4d1ac1f0660da0a2;hp=d391ea63114132a85c4b922e1eca1e6960cfc7af;hpb=ce6754235b423610e91f5300e1555c2e4ee1c03a;p=linux-2.6-omap-h63xx.git

diff --git a/Documentation/networking/multiqueue.txt b/Documentation/networking/multiqueue.txt
index d391ea63114..4caa0e314cc 100644
--- a/Documentation/networking/multiqueue.txt
+++ b/Documentation/networking/multiqueue.txt
@@ -24,4 +24,56 @@ netif_{start|stop|wake}_subqueue() functions to manage each queue while the
 device is still operational.  netdev->queue_lock is still used when the device
 comes online or when it's completely shut down (unregister_netdev(), etc.).
 
-Author: Peter P. Waskiewicz Jr. <peter.p.waskiewicz.jr@intel.com>
+
+Section 2: Qdisc support for multiqueue devices
+
+-----------------------------------------------
+
+Currently two qdiscs are optimized for multiqueue devices.  The first is the
+default pfifo_fast qdisc.  This qdisc supports one qdisc per hardware queue.
+A new round-robin qdisc, sch_multiq also supports multiple hardware queues. The
+qdisc is responsible for classifying the skb's and then directing the skb's to
+bands and queues based on the value in skb->queue_mapping.  Use this field in
+the base driver to determine which queue to send the skb to.
+
+sch_multiq has been added for hardware that wishes to avoid head-of-line
+blocking.  It will cycle though the bands and verify that the hardware queue
+associated with the band is not stopped prior to dequeuing a packet.
+
+On qdisc load, the number of bands is based on the number of queues on the
+hardware.  Once the association is made, any skb with skb->queue_mapping set,
+will be queued to the band associated with the hardware queue.
+
+
+Section 3: Brief howto using MULTIQ for multiqueue devices
+---------------------------------------------------------------
+
+The userspace command 'tc,' part of the iproute2 package, is used to configure
+qdiscs.  To add the MULTIQ qdisc to your network device, assuming the device
+is called eth0, run the following command:
+
+# tc qdisc add dev eth0 root handle 1: multiq
+
+The qdisc will allocate the number of bands to equal the number of queues that
+the device reports, and bring the qdisc online.  Assuming eth0 has 4 Tx
+queues, the band mapping would look like:
+
+band 0 => queue 0
+band 1 => queue 1
+band 2 => queue 2
+band 3 => queue 3
+
+Traffic will begin flowing through each queue based on either the simple_tx_hash
+function or based on netdev->select_queue() if you have it defined.
+
+The behavior of tc filters remains the same.  However a new tc action,
+skbedit, has been added.  Assuming you wanted to route all traffic to a
+specific host, for example 192.168.0.3, through a specific queue you could use
+this action and establish a filter such as:
+
+tc filter add dev eth0 parent 1: protocol ip prio 1 u32 \
+	match ip dst 192.168.0.3 \
+	action skbedit queue_mapping 3
+
+Author: Alexander Duyck <alexander.h.duyck@intel.com>
+Original Author: Peter P. Waskiewicz Jr. <peter.p.waskiewicz.jr@intel.com>