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 hardware 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 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 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 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 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 priority.  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, <john.r.fastabend@intel.com>

iproute2                                          24 Sept 2013                                         MQPRIO(8)