Documentation: networking: TC queue based filtering

Add tc-queue-filters.rst with notes on TC filters for
selecting a set of queues and/or a queue.

Signed-off-by: Amritha Nambiar <amritha.nambiar@intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Amritha Nambiar 2022-10-21 00:58:50 -07:00 committed by Paolo Abeni
parent 143b86f346
commit d5ae8ecf38
2 changed files with 38 additions and 0 deletions

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@ -104,6 +104,7 @@ Contents:
switchdev
sysfs-tagging
tc-actions-env-rules
tc-queue-filters
tcp-thin
team
timestamping

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.. SPDX-License-Identifier: GPL-2.0
=========================
TC queue based filtering
=========================
TC can be used for directing traffic to either a set of queues or
to a single queue on both the transmit and receive side.
On the transmit side:
1) TC filter directing traffic to a set of queues is achieved
using the action skbedit priority for Tx priority selection,
the priority maps to a traffic class (set of queues) when
the queue-sets are configured using mqprio.
2) TC filter directs traffic to a transmit queue with the action
skbedit queue_mapping $tx_qid. The action skbedit queue_mapping
for transmit queue is executed in software only and cannot be
offloaded.
Likewise, on the receive side, the two filters for selecting set of
queues and/or a single queue are supported as below:
1) TC flower filter directs incoming traffic to a set of queues using
the 'hw_tc' option.
hw_tc $TCID - Specify a hardware traffic class to pass matching
packets on to. TCID is in the range 0 through 15.
2) TC filter with action skbedit queue_mapping $rx_qid selects a
receive queue. The action skbedit queue_mapping for receive queue
is supported only in hardware. Multiple filters may compete in
the hardware for queue selection. In such case, the hardware
pipeline resolves conflicts based on priority. On Intel E810
devices, TC filter directing traffic to a queue have higher
priority over flow director filter assigning a queue. The hash
filter has lowest priority.