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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@offset2 ...  ] [ hw 1|0 ]

DESCRIPTION
       The MQPRIO qdisc is a simple queuing discipline that allows mapping traffic flows to hard‐
       ware queue ranges using priorities and a configurable priority to traffic class mapping. A
       traffic class in this context 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  hard‐
       ware driver to match the hardware QOS structures.

       Enabled  hardware can provide hardware QOS with the ability to steer traffic flows to des‐
       ignated traffic classes provided by this qdisc.  Configuring the hardware based QOS mecha‐
       nism 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 mapping 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  rea‐
       sonably 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 provide 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 prior‐
              ity.  iptables(8)

       with net_prio cgroups
              The net_prio cgroup can be used to set the priority of all  sockets  belong  to  an
              application. See kernel and cgroup documentation for details.

QDISC PARAMETERS
       num_tc Number of traffic classes to use upto 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, 

iproute2                                   24 Sept 2013                                 MQPRIO(8)

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