man/man8/tc-taprio.8

   1 .TH TAPRIO 8 "25 Sept 2018" "iproute2" "Linux"
   2 .SH NAME
   3 TAPRIO \- Time Aware Priority Shaper
   4 .SH SYNOPSIS
   5 .B tc qdisc ... dev
   6 dev
   7 .B parent
   8 classid
   9 .B [ handle
  10 major:
  11 .B ] taprio num_tc
  12 tcs
  13 .ti +8
  14 .B map
  15 P0 P1 P2 ...
  16 .B queues
  17 count1@offset1 count2@offset2 ...
  18 .ti +8
  19 .B base-time
  20 base-time
  21 .B clockid
  22 clockid
  23 .ti +8
  24 .B sched-entry
  25 <command 1> <gate mask 1> <interval 1>
  26 .ti +8
  27 .B sched-entry
  28 <command 2> <gate mask 2> <interval 2>
  29 .ti +8
  30 .B sched-entry
  31 <command 3> <gate mask 3> <interval 3>
  32 .ti +8
  33 .B sched-entry
  34 <command N> <gate mask N> <interval N>
  35
  36 .SH DESCRIPTION
  37 The TAPRIO qdisc implements a simplified version of the scheduling
  38 state machine defined by IEEE 802.1Q-2018 Section 8.6.9, which allows
  39 configuration of a sequence of gate states, where each gate state
  40 allows outgoing traffic for a subset (potentially empty) of traffic
  41 classes.
  42
  43 How traffic is mapped to different hardware queues is similar to
  44 .BR mqprio(8)
  45 and so the
  46 .B map
  47 and
  48 .B queues
  49 parameters have the same meaning.
  50
  51 The other parameters specify the schedule, and at what point in time
  52 it should start (it can behave as the schedule started in the past).
  53
  54 .SH PARAMETERS
  55 .TP
  56 num_tc
  57 .BR
  58 Number of traffic classes to use. Up to 16 classes supported.
  59
  60 .TP
  61 map
  62 .br
  63 The priority to traffic class map. Maps priorities 0..15 to a specified
  64 traffic class. See
  65 .BR mqprio(8)
  66 for more details.
  67
  68 .TP
  69 queues
  70 .br
  71 Provide count and offset of queue range for each traffic class. In the
  72 format,
  73 .B count@offset.
  74 Queue ranges for each traffic classes cannot overlap and must be a
  75 contiguous range of queues.
  76
  77 .TP
  78 base-time
  79 .br
  80 Specifies the instant in nanoseconds, using the reference of
  81 .B clockid,
  82 defining the time when the schedule starts. If 'base-time' is a time
  83 in the past, the schedule will start at
  84
  85 base-time + (N * cycle-time)
  86
  87 where N is the smallest integer so the resulting time is greater than
  88 "now", and "cycle-time" is the sum of all the intervals of the entries
  89 in the schedule;
  90
  91 .TP
  92 clockid
  93 .br
  94 Specifies the clock to be used by qdisc's internal timer for measuring
  95 time and scheduling events.
  96
  97 .TP
  98 sched-entry
  99 .br
 100 There may multiple
 101 .B sched-entry
 102 parameters in a single schedule. Each one has the
 103
 104 sched-entry <command> <gatemask> <interval>
 105
 106 format. The only supported <command> is "S", which
 107 means "SetGateStates", following the IEEE 802.1Q-2018 definition
 108 (Table 8-7). <gate mask> is a bitmask where each bit is a associated
 109 with a traffic class, so bit 0 (the least significant bit) being "on"
 110 means that traffic class 0 is "active" for that schedule entry.
 111 <interval> is a time duration, in nanoseconds, that specifies for how
 112 long that state defined by <command> and <gate mask> should be held
 113 before moving to the next entry.
 114
 115 .SH EXAMPLES
 116
 117 The following example shows how an traffic schedule with three traffic
 118 classes ("num_tc 3"), which are separated different traffic classes,
 119 we are going to call these TC 0, TC 1 and TC 2. We could read the
 120 "map" parameter below as: traffic with priority 3 is classified as TC
 121 0, priority 2 is classified as TC 1 and the rest is classified as TC
 122 2.
 123
 124 The schedule will start at instant 1528743495910289987 using the
 125 reference CLOCK_TAI. The schedule is composed of three entries each of
 126 300us duration.
 127
 128 .EX
 129 # tc qdisc replace dev eth0 parent root handle 100 taprio \\
 130               num_tc 3 \\
 131               map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 \\
 132               queues 1@0 1@1 2@2 \\
 133               base-time 1528743495910289987 \\
 134               sched-entry S 01 300000 \\
 135               sched-entry S 02 300000 \\
 136               sched-entry S 04 300000 \\
 137               clockid CLOCK_TAI
 138 .EE
 139
 140
 141 .SH AUTHORS
 142 Vinicius Costa Gomes <vinicius.gomes@intel.com>