MQPRIO(8)			     Linux			     MQPRIO(8)



NAME
       MQPRIO - Multiqueue Priority Qdisc (Offloaded Hardware QOS)

SYNOPSIS
       tc  qdisc ... dev dev ( parent classid | root) [ handle major: ] mqprio
       [ numtc tcs ] [ map P0 P1 P2...	] [ queues count1@offset1  count2@off-
       set2 ...	 ] [ hw 1|0 ]


DESCRIPTION
       The  MQPRIO  qdisc  is  a simple queuing discipline that allows mapping
       traffic flows to hardware queue ranges using priorities and  a  config-
       urable  priority to traffic class mapping. A traffic class in this con-
       text is a set of contiguous qdisc classes which map 1:1	to  a  set  of
       hardware exposed queues.

       By  default the qdisc allocates a pfifo qdisc (packet limited first in,
       first out queue) per TX queue exposed by the lower layer device.	 Other
       queuing	disciplines  may  be  added subsequently. Packets are enqueued
       using the map parameter and hashed across the indicated queues  in  the
       offset  and  count.   By default these parameters are configured by the
       hardware driver to match the hardware QOS structures.

       Enabled hardware can provide hardware QOS with  the  ability  to	 steer
       traffic	flows  to  designated  traffic classes provided by this qdisc.
       Configuring the hardware based QOS mechanism is outside	the  scope  of
       this  qdisc.  Tools  such  as  lldpad and ethtool exist to provide this
       functionality. Also further qdiscs may  be  added  to  the  classes  of
       MQPRIO to create more complex configurations.


ALGORITHM
       On creation with 'tc qdisc add', eight traffic classes are created map-
       ping priorities 0..7 to traffic classes	0..7  and  priorities  greater
       than  7	to  traffic class 0. This requires base driver support and the
       creation will fail on devices that do not support hardware QOS schemes.

       These defaults can be overridden using the qdisc parameters.  Providing
       the 'hw 0' flag allows software to run without hardware coordination.

       If  hardware coordination is being used and arguments are provided that
       the hardware can not support then an error is returned. For many	 users
       hardware defaults should work reasonably well.

       As one specific example numerous Ethernet cards support the 802.1Q link
       strict priority transmission selection algorithm (TSA). MQPRIO  enabled
       hardware	 in conjunction with the classification methods below can pro-
       vide hardware offloaded support for this TSA.


CLASSIFICATION
       Multiple methods are available to set the  SKB  priority	 which	MQPRIO
       uses to select which traffic class to enqueue the packet.

       From user space
	      A	 process with sufficient privileges can encode the destination
	      class directly with SO_PRIORITY, see socket(7).

       with iptables/nftables
	      An iptables/nftables rule can be created to match traffic	 flows
	      and set the priority.  iptables(8)

       with net_prio cgroups
	      The net_prio cgroup can be used to set the priority of all sock-
	      ets belong to an application. See kernel and  cgroup  documenta-
	      tion for details.


QDISC PARAMETERS
       num_tc Number of traffic classes to use. Up to 16 classes supported.


       map    The  priority  to	 traffic class map. Maps priorities 0..15 to a
	      specified traffic class.


       queues Provide count and offset of queue range for each traffic	class.
	      In  the  format,	count@offset.	Queue  ranges for each traffic
	      classes cannot overlap and must be a contiguous range of queues.


       hw     Set to 1 to use hardware QOS defaults.  Set  to  0  to  override
	      hardware defaults with user specified values.


AUTHORS
       John Fastabend, <john.r.fastabend@intel.com>



iproute2			 24 Sept 2013			     MQPRIO(8)