31. Soft NIC Poll Mode Driver

The Soft NIC allows building custom NIC pipelines in software. The Soft NIC pipeline is DIY and reconfigurable through firmware (DPDK Packet Framework script).

The Soft NIC leverages the DPDK Packet Framework libraries (librte_port, librte_table and librte_pipeline) to make it modular, flexible and extensible with new functionality. Please refer to DPDK Programmer’s Guide, Chapter Packet Framework and DPDK Sample Application User Guide, Chapter IP Pipeline Application for more details.

The Soft NIC is configured through the standard DPDK ethdev API (ethdev, flow, QoS, security). The internal framework is not externally visible.

Key benefits:
  • Can be used to augment missing features to HW NICs.
  • Allows consumption of advanced DPDK features without application redesign.
  • Allows out-of-the-box performance boost of DPDK consumers applications simply by instantiating this type of Ethernet device.

31.1. Flow

  • Device creation: Each Soft NIC instance is a virtual device.
  • Device start: The Soft NIC firmware script is executed every time the device is started. The firmware script typically creates several internal objects, such as: memory pools, SW queues, traffic manager, action profiles, pipelines, etc.
  • Device stop: All the internal objects that were previously created by the firmware script during device start are now destroyed.
  • Device run: Each Soft NIC device needs one or several CPU cores to run. The firmware script maps each internal pipeline to a CPU core. Multiple pipelines can be mapped to the same CPU core. In order for a given pipeline assigned to CPU core X to run, the application needs to periodically call on CPU core X the rte_pmd_softnic_run() function for the current Soft NIC device.
  • Application run: The application reads packets from the Soft NIC device RX queues and writes packets to the Soft NIC device TX queues.

31.2. Supported Operating Systems

Any Linux distribution fulfilling the conditions described in System Requirements section of the DPDK documentation or refer to DPDK Release Notes.

31.3. Build options

The default PMD configuration available in the common_linuxapp configuration file:

CONFIG_RTE_LIBRTE_PMD_SOFTNIC=y

Once the DPDK is built, all the DPDK applications include support for the Soft NIC PMD.

31.4. Soft NIC PMD arguments

The user can specify below arguments in EAL --vdev options to create the Soft NIC device instance:

–vdev “net_softnic0,firmware=firmware.cli,conn_port=8086”
  1. firmware: path to the firmware script used for Soft NIC configuration. The example “firmware” script is provided at drivers/net/softnic/. (Optional: No, Default = NA)
  2. conn_port: tcp connection port (non-zero value) used by remote client (for examples- telnet, netcat, etc.) to connect and configure Soft NIC device in run-time. (Optional: yes, Default value: 0, no connection with external client)
  3. cpu_id: numa node id. (Optional: yes, Default value: 0)
  4. tm_n_queues: number of traffic manager’s scheduler queues. The traffic manager is based on DPDK librte_sched library. (Optional: yes, Default value: 65,536 queues)
  5. tm_qsize0: size of scheduler queue 0 per traffic class of the pipes/subscribers. (Optional: yes, Default: 64)
  6. tm_qsize1: size of scheduler queue 1 per traffic class of the pipes/subscribers. (Optional: yes, Default: 64)
  7. tm_qsize2: size of scheduler queue 2 per traffic class of the pipes/subscribers. (Optional: yes, Default: 64)
  8. tm_qsize3: size of scheduler queue 3 per traffic class of the pipes/subscribers. (Optional: yes, Default: 64)

31.5. Soft NIC testing

  • Run testpmd application in Soft NIC forwarding mode with loopback feature enabled on Soft NIC port:

    ./testpmd -c 0x3 --vdev 'net_softnic0,firmware=<script path>/firmware.cli,cpu_id=0,conn_port=8086' -- -i
     --forward-mode=softnic --portmask=0x2

    ...
Interactive-mode selected
Set softnic packet forwarding mode
...
Configuring Port 0 (socket 0)
Port 0: 90:E2:BA:37:9D:DC
Configuring Port 1 (socket 0)

; SPDX-License-Identifier: BSD-3-Clause
; Copyright(c) 2018 Intel Corporation

link LINK dev 0000:02:00.0

pipeline RX period 10 offset_port_id 0
pipeline RX port in bsz 32 link LINK rxq 0
pipeline RX port out bsz 32 swq RXQ0
pipeline RX table match stub
pipeline RX port in 0 table 0

pipeline TX period 10 offset_port_id 0
pipeline TX port in bsz 32 swq TXQ0
pipeline TX port out bsz 32 link LINK txq 0
pipeline TX table match stub
pipeline TX port in 0 table 0

thread 1 pipeline RX enable
thread 1 pipeline TX enable
Port 1: 00:00:00:00:00:00
Checking link statuses...
Done
testpmd>

  • Start forwarding

    testpmd> start
softnic packet forwarding - ports=1 - cores=1 - streams=1 - NUMA support enabled, MP over anonymous pages disabled
Logical Core 1 (socket 0) forwards packets on 1 streams:
RX P=2/Q=0 (socket 0) -> TX P=2/Q=0 (socket 0) peer=02:00:00:00:00:02

softnic packet forwarding packets/burst=32
nb forwarding cores=1 - nb forwarding ports=1
port 0: RX queue number: 1 Tx queue number: 1
Rx offloads=0x1000 Tx offloads=0x0
RX queue: 0
RX desc=512 - RX free threshold=32
RX threshold registers: pthresh=8 hthresh=8  wthresh=0
RX Offloads=0x0
TX queue: 0
TX desc=512 - TX free threshold=32
TX threshold registers: pthresh=32 hthresh=0  wthresh=0
TX offloads=0x0 - TX RS bit threshold=32
port 1: RX queue number: 1 Tx queue number: 1
Rx offloads=0x0 Tx offloads=0x0
RX queue: 0
RX desc=0 - RX free threshold=0
RX threshold registers: pthresh=0 hthresh=0  wthresh=0
RX Offloads=0x0
TX queue: 0
TX desc=0 - TX free threshold=0
TX threshold registers: pthresh=0 hthresh=0  wthresh=0
TX offloads=0x0 - TX RS bit threshold=0

  • Start remote client (e.g. telnet) to communicate with the softnic device:

    $ telnet 127.0.0.1 8086
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.

Welcome to Soft NIC!

softnic>

  • Add/update Soft NIC pipeline table match-action entries from telnet client:

    softnic> pipeline RX table 0 rule add match default action fwd port 0
softnic> pipeline TX table 0 rule add match default action fwd port 0

31.6. Soft NIC Firmware

The Soft NIC firmware, for example- softnic/firmware.cli, consists of following CLI commands for creating and managing software based NIC pipelines. For more details, please refer to CLI command description provided in softnic/rte_eth_softnic_cli.c.

  • Physical port for packets send/receive:

    link LINK dev 0000:02:00.0

  • Pipeline create:

    pipeline RX period 10 offset_port_id 0           (Soft NIC rx-path pipeline)
pipeline TX period 10 offset_port_id 0           (Soft NIC tx-path pipeline)

  • Pipeline input/output port create

    pipeline RX port in bsz 32 link LINK rxq 0      (Soft NIC rx pipeline input port)
pipeline RX port out bsz 32 swq RXQ0            (Soft NIC rx pipeline output port)
pipeline TX port in bsz 32 swq TXQ0             (Soft NIC tx pipeline input port)
pipeline TX port out bsz 32 link LINK txq 0     (Soft NIC tx pipeline output port)

  • Pipeline table create

    pipeline RX table match stub             (Soft NIC rx pipeline match-action table)
pipeline TX table match stub             (Soft NIC tx pipeline match-action table)

  • Pipeline input port connection with table

    pipeline RX port in 0 table 0          (Soft NIC rx pipeline input port 0 connection with table 0)
pipeline TX port in 0 table 0          (Soft NIC tx pipeline input port 0 connection with table 0)

  • Pipeline table match-action rules add

    pipeline RX table 0 rule add match default action fwd port 0        (Soft NIC rx pipeline table 0 rule)
pipeline TX table 0 rule add match default action fwd port 0        (Soft NIC tx pipeline table 0 rule)

  • Enable pipeline on CPU thread

    thread 1 pipeline RX enable        (Soft NIC rx pipeline enable on cpu thread id 1)
thread 1 pipeline TX enable        (Soft NIC tx pipeline enable on cpu thread id 1)