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+.TH TAPRIO 8 "25 Sept 2018" "iproute2" "Linux"
+.SH NAME
+TAPRIO \- Time Aware Priority Shaper
+.SH SYNOPSIS
+.B tc qdisc ... dev
+dev
+.B parent
+classid
+.B [ handle
+major:
+.B ] taprio num_tc
+tcs
+.ti +8
+.B map
+P0 P1 P2 ...
+.B queues
+count1@offset1 count2@offset2 ...
+.ti +8
+.B base-time
+base-time
+.B clockid
+clockid
+.ti +8
+.B sched-entry
+<command 1> <gate mask 1> <interval 1>
+.ti +8
+.B sched-entry
+<command 2> <gate mask 2> <interval 2>
+.ti +8
+.B sched-entry
+<command 3> <gate mask 3> <interval 3>
+.ti +8
+.B sched-entry
+<command N> <gate mask N> <interval N>
+
+.SH DESCRIPTION
+The TAPRIO qdisc implements a simplified version of the scheduling
+state machine defined by IEEE 802.1Q-2018 Section 8.6.9, which allows
+configuration of a sequence of gate states, where each gate state
+allows outgoing traffic for a subset (potentially empty) of traffic
+classes.
+
+How traffic is mapped to different hardware queues is similar to
+.BR mqprio(8)
+and so the
+.B map
+and
+.B queues
+parameters have the same meaning.
+
+The other parameters specify the schedule, and at what point in time
+it should start (it can behave as the schedule started in the past).
+
+.SH PARAMETERS
+.TP
+num_tc
+.BR
+Number of traffic classes to use. Up to 16 classes supported.
+
+.TP
+map
+.br
+The priority to traffic class map. Maps priorities 0..15 to a specified
+traffic class. See
+.BR mqprio(8)
+for more details.
+
+.TP
+queues
+.br
+Provide count and offset of queue range for each traffic class. In the
+format,
+.B count@offset.
+Queue ranges for each traffic classes cannot overlap and must be a
+contiguous range of queues.
+
+.TP
+base-time
+.br
+Specifies the instant in nanoseconds, using the reference of
+.B clockid,
+defining the time when the schedule starts. If 'base-time' is a time
+in the past, the schedule will start at
+
+base-time + (N * cycle-time)
+
+where N is the smallest integer so the resulting time is greater than
+"now", and "cycle-time" is the sum of all the intervals of the entries
+in the schedule;
+
+.TP
+clockid
+.br
+Specifies the clock to be used by qdisc's internal timer for measuring
+time and scheduling events. This argument must be omitted when using the
+full-offload feature (flags 0x2), since in that case, the clockid is
+implicitly /dev/ptpN (where N is given by
+.B ethtool -T eth0 | grep 'PTP Hardware Clock'
+), and therefore not necessarily synchronized with the system's CLOCK_TAI.
+
+.TP
+sched-entry
+.br
+There may multiple
+.B sched-entry
+parameters in a single schedule. Each one has the
+
+sched-entry <command> <gatemask> <interval>
+
+format. The only supported <command> is "S", which
+means "SetGateStates", following the IEEE 802.1Q-2018 definition
+(Table 8-7). <gate mask> is a bitmask where each bit is a associated
+with a traffic class, so bit 0 (the least significant bit) being "on"
+means that traffic class 0 is "active" for that schedule entry.
+<interval> is a time duration, in nanoseconds, that specifies for how
+long that state defined by <command> and <gate mask> should be held
+before moving to the next entry.
+
+.TP
+flags
+.br
+This is a bit mask which specifies different modes for taprio.
+.RS
+.TP
+.I 0x1
+Enables the txtime-assist feature. In this mode, taprio will set the transmit
+timestamp depending on the interval in which the packet needs to be
+transmitted. It will then utililize the
+.BR etf(8)
+qdisc to sort and transmit the packets at the right time. The second example
+can be used as a reference to configure this mode.
+.TP
+.I 0x2
+Enables the full-offload feature. In this mode, taprio will pass the gate
+control list to the NIC which will execute it cyclically in hardware.
+When using full-offload, there is no need to specify the
+.B clockid
+argument.
+
+The txtime-assist and full-offload features are mutually exclusive, i.e.
+setting flags to 0x3 is invalid.
+.RE
+
+.TP
+txtime-delay
+.br
+This parameter is specific to the txtime offload mode. It specifies the maximum
+time a packet might take to reach the network card from the taprio qdisc. The
+value should always be greater than the delta specified in the
+.BR etf(8)
+qdisc.
+
+.SH EXAMPLES
+
+The following example shows how an traffic schedule with three traffic
+classes ("num_tc 3"), which are separated different traffic classes,
+we are going to call these TC 0, TC 1 and TC 2. We could read the
+"map" parameter below as: traffic with priority 3 is classified as TC
+0, priority 2 is classified as TC 1 and the rest is classified as TC
+2.
+
+The schedule will start at instant 1528743495910289987 using the
+reference CLOCK_TAI. The schedule is composed of three entries each of
+300us duration.
+
+.EX
+# tc qdisc replace dev eth0 parent root handle 100 taprio \\
+              num_tc 3 \\
+              map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 \\
+              queues 1@0 1@1 2@2 \\
+              base-time 1528743495910289987 \\
+              sched-entry S 01 300000 \\
+              sched-entry S 02 300000 \\
+              sched-entry S 04 300000 \\
+              clockid CLOCK_TAI
+.EE
+
+Following is an example to enable the txtime offload mode in taprio. See
+.BR etf(8)
+for more information about configuring the ETF qdisc.
+
+.EX
+# tc qdisc replace dev eth0 parent root handle 100 taprio \\
+              num_tc 3 \\
+              map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 \\
+              queues 1@0 1@0 1@0 \\
+              base-time 1528743495910289987 \\
+              sched-entry S 01 300000 \\
+              sched-entry S 02 300000 \\
+              sched-entry S 04 400000 \\
+              flags 0x1 \\
+              txtime-delay 200000 \\
+              clockid CLOCK_TAI
+
+# tc qdisc replace dev $IFACE parent 100:1 etf skip_skb_check \\
+              offload delta 200000 clockid CLOCK_TAI
+.EE
+
+The following is a schedule in full offload mode. The
+.B base-time
+is 200 ns and the
+.B cycle-time
+is implicitly calculated as the sum of all
+.B sched-entry
+durations (i.e. 20 us + 20 us + 60 us = 100 us). Although the base-time is in
+the past, the hardware will start executing the schedule at a PTP time equal to
+the smallest integer multiple of 100 us, plus 200 ns, that is larger than the
+NIC's current PTP time.
+
+.EX
+# tc qdisc add dev eth0 parent root taprio \\
+              num_tc 8 \\
+              map 0 1 2 3 4 5 6 7 \\
+              queues 1@0 1@1 1@2 1@3 1@4 1@5 1@6 1@7 \\
+              base-time 200 \\
+              sched-entry S 80 20000 \\
+              sched-entry S a0 20000 \\
+              sched-entry S df 60000 \\
+              flags 0x2
+.EE
+
+.SH AUTHORS
+Vinicius Costa Gomes <vinicius.gomes@intel.com>