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NAME | SYNOPSIS | DESCRIPTION | ALGORITHM | CLASSIFICATION | QDISC PARAMETERS | AUTHORS | COLOPHON |
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 ]
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.
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 use hardware QOS defaults. Set to 0 to override
hardware defaults with user specified values.
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 2017-07-05. 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)