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NAME | SYNOPSIS | DESCRIPTION | ALGORITHM | CLASSIFICATION | QDISC PARAMETERS | AUTHORS | COLOPHON |
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MQPRIO(8) Linux MQPRIO(8)
MQPRIO - Multiqueue Priority Qdisc (Offloaded Hardware QOS)
tc qdisc ... dev dev ( parent classid | root) [ handle major: ]
mqprio [ numtc tcs ] [ map P0 P1 P2... ] [ queues count1@offset1
count2@offset2 ... ] [ hw 1|0 ] [ mode dcb|channel] ] [ shaper dcb|
[ bw_rlimit min_rate min_rate1 min_rate2 ... max_rate max_rate1
max_rate2 ... ]]
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.
Channel mode supports full offload of the mqprio options, the traffic
classes, the queue configurations and QOS attributes to the hardware.
Enabled hardware can provide hardware QOS with the ability to steer
traffic flows to designated traffic classes provided by this qdisc.
Hardware based QOS is configured using the shaper parameter.
bw_rlimit with minimum and maximum bandwidth rates can be used for
setting transmission rates on each traffic class. Also further qdiscs
may be added to the classes of MQPRIO to create more complex
configurations.
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.
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.
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 support hardware offload. Set to 0 to configure
user specified values in software only.
mode Set to channel for full use of the mqprio options. Use dcb to
offload only TC values and use hardware QOS defaults.
Supported with 'hw' set to 1 only.
shaper Use bw_rlimit to set bandwidth rate limits for a traffic
class. Use dcb for hardware QOS defaults. Supported with 'hw'
set to 1 only.
min_rate
Minimum value of bandwidth rate limit for a traffic class.
max_rate
Maximum value of bandwidth rate limit for a traffic class.
John Fastabend, <john.r.fastabend@intel.com>
This page is part of the iproute2 (utilities for controlling TCP/IP
networking and traffic) project. Information about the project can
be found at
⟨http://www.linuxfoundation.org/collaborate/workgroups/networking/iproute2⟩.
If you have a bug report for this manual page, send it to
netdev@vger.kernel.org, shemminger@osdl.org. This page was obtained
from the project's upstream Git repository
⟨git://git.kernel.org/pub/scm/linux/kernel/git/shemminger/iproute2.git⟩
on 2018-02-02. (At that time, the date of the most recent commit
that was found in the repository was 2018-01-29.) If you discover
any rendering problems in this HTML version of the page, or you
believe there is a better or more up-to-date source for the page, or
you have corrections or improvements to the information in this
COLOPHON (which is not part of the original manual page), send a mail
to man-pages@man7.org
iproute2 24 Sept 2013 MQPRIO(8)
Pages that refer to this page: tc(8)
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