1MQPRIO(8) Linux MQPRIO(8)
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6 MQPRIO - Multiqueue Priority Qdisc (Offloaded Hardware QOS)
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9 tc qdisc ... dev dev ( parent classid | root) [ handle major: ] mqprio
10 [ numtc tcs ] [ map P0 P1 P2... ] [ queues count1@offset1 count2@off‐
11 set2 ... ] [ hw 1|0 ]
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15 The MQPRIO qdisc is a simple queuing discipline that allows mapping
16 traffic flows to hardware queue ranges using priorities and a config‐
17 urable priority to traffic class mapping. A traffic class in this con‐
18 text is a set of contiguous qdisc classes which map 1:1 to a set of
19 hardware exposed queues.
20 By default the qdisc allocates a pfifo qdisc (packet limited first in,
22 first out queue) per TX queue exposed by the lower layer device. Other
23 queuing disciplines may be added subsequently. Packets are enqueued
24 using the map parameter and hashed across the indicated queues in the
25 offset and count. By default these parameters are configured by the
26 hardware driver to match the hardware QOS structures.
27 Enabled hardware can provide hardware QOS with the ability to steer
29 traffic flows to designated traffic classes provided by this qdisc.
30 Configuring the hardware based QOS mechanism is outside the scope of
31 this qdisc. Tools such as lldpad and ethtool exist to provide this
32 functionality. Also further qdiscs may be added to the classes of
33 MQPRIO to create more complex configurations.
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37 On creation with 'tc qdisc add', eight traffic classes are created map‐
38 ping priorities 0..7 to traffic classes 0..7 and priorities greater
39 than 7 to traffic class 0. This requires base driver support and the
40 creation will fail on devices that do not support hardware QOS schemes.
41 These defaults can be overridden using the qdisc parameters. Providing
43 the 'hw 0' flag allows software to run without hardware coordination.
44 If hardware coordination is being used and arguments are provided that
46 the hardware can not support then an error is returned. For many users
47 hardware defaults should work reasonably well.
48 As one specific example numerous Ethernet cards support the 802.1Q link
50 strict priority transmission selection algorithm (TSA). MQPRIO enabled
51 hardware in conjunction with the classification methods below can pro‐
52 vide hardware offloaded support for this TSA.
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56 Multiple methods are available to set the SKB priority which MQPRIO
57 uses to select which traffic class to enqueue the packet.
58 From user space
60 A process with sufficient privileges can encode the destination
61 class directly with SO_PRIORITY, see socket(7).
62 with iptables/nftables
64 An iptables/nftables rule can be created to match traffic flows
65 and set the priority. iptables(8)
66 with net_prio cgroups
68 The net_prio cgroup can be used to set the priority of all sock‐
69 ets belong to an application. See kernel and cgroup documenta‐
70 tion for details.
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74 num_tc Number of traffic classes to use. Up to 16 classes supported.
75 map The priority to traffic class map. Maps priorities 0..15 to a
78 specified traffic class.
79 queues Provide count and offset of queue range for each traffic class.
82 In the format, count@offset. Queue ranges for each traffic
83 classes cannot overlap and must be a contiguous range of queues.
84 hw Set to 1 to use hardware QOS defaults. Set to 0 to override
87 hardware defaults with user specified values.
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91 John Fastabend, <john.r.fastabend@intel.com>
92iproute2 24 Sept 2013 MQPRIO(8)