如何在DPDK testpmd中使用一个NIC来设置一个循环转发到TX数据包并将它们本身RX？

Question

我想要实现这样一个场景：

1. -- NIC's RXQ 0
2. NIC中接收的数据包得到它，并以某种方式将其放入TXQ 0
3. (NIC的努力？)，该数据包将被发送到NIC的RXQ 0，并返回到步骤1.

。

我认为前进模式tx_first是我所需要的。

NIC: PMD: MLX5版本: 5.0-1.0.0.0

DPDK版本: 20.11.1

全命令行

./testpmd.sh 0 11-12 1 1 testpmd0 3b:00.0

#testpmd.sh
#if [ $# -ne 6 ]
#then
#       echo $0" <socket_id> <core_list> <core_num> <queue_num> <prefix>"
#       exit 255
#fi
        ./build/app/dpdk-testpmd -l $2 -n 4 \
        --socket-mem=2048,2048 \
        -a $6,txq_inline=200,txq_mpw
        --file-prefix=$5 \
        -- \
        -i \
        --mbcache=512 \
        --txonly-multi-flow \
        --rxd=2048 --txd=2048 \
        --rxq=$4 --txq=$4 \
        --nb-cores=$3 \
        --port-topology=loop \
        --numa --socket-num=$1 --port-numa-config=0,$1 --ring-numa-config=0,3,$1

但是在我设置命令行arg --port-topology=loop并尝试了start tx_first之后

溪流是：

testpmd> start tx_first
io packet forwarding - ports=1 - cores=1 - streams=1 - NUMA support enabled, MP allocation mode: native
Logical Core 12 (socket 0) forwards packets on 1 streams:
  RX P=0/Q=0 (socket 0) -> TX P=0/Q=0 (socket 0) peer=02:00:00:00:00:00

我拿到了数据：

testpmd> show fwd stats all

  ---------------------- Forward statistics for port 0  ----------------------
  RX-packets: 6              RX-dropped: 0             RX-total: 6
  TX-packets: 38             TX-dropped: 0             TX-total: 38
  ----------------------------------------------------------------------------

  +++++++++++++++ Accumulated forward statistics for all ports+++++++++++++++
  RX-packets: 6              RX-dropped: 0             RX-total: 6
  TX-packets: 38             TX-dropped: 0             TX-total: 38
  ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

#32 same packets like this
restore info: - no tunnel info - no outer header - no miss group
  src=04:3F:72:CB:21:46 - dst=02:00:00:00:00:00 - type=0x0800 - length=64 - nb_segs=1 - sw ptype: L2_ETHER L3_IPV4 L4_UDP  - l2_len=14 - l3_len=20 - l4_len=8 - Send queue=0x0
  ol_flags: PKT_RX_L4_CKSUM_UNKNOWN PKT_RX_IP_CKSUM_UNKNOWN PKT_RX_OUTER_L4_CKSUM_UNKNOWN

# discrete but same packets received
testpmd> port 0/queue 0: received 1 packets
restore info: - no tunnel info - no outer header - no miss group
  src=F4:74:88:8C:11:86 - dst=01:80:C2:00:00:00 - type=0x0069 - length=119 - nb_segs=1 - hw ptype: L2_ETHER  - sw ptype: L2_ETHER  - l2_len=14 - Receive queue=0x0
  ol_flags: PKT_RX_L4_CKSUM_UNKNOWN PKT_RX_IP_CKSUM_UNKNOWN PKT_RX_OUTER_L4_CKSUM_UNKNOWN
port 0/queue 0: sent 1 packets
restore info: - no tunnel info - no outer header - no miss group
  src=F4:74:88:8C:11:86 - dst=01:80:C2:00:00:00 - type=0x0069 - length=119 - nb_segs=1 - hw ptype: L2_ETHER  - sw ptype: L2_ETHER  - l2_len=14 - Send queue=0x0
  ol_flags: PKT_RX_L4_CKSUM_UNKNOWN PKT_RX_IP_CKSUM_UNKNOWN PKT_RX_OUTER_L4_CKSUM_UNKNOWN
port 0/queue 0: received 1 packets
restore info: - no tunnel info - no outer header - no miss group
  src=F4:74:88:8C:11:86 - dst=01:80:C2:00:00:00 - type=0x0069 - length=119 - nb_segs=1 - hw ptype: L2_ETHER  - sw ptype: L2_ETHER  - l2_len=14 - Receive queue=0x0
  ol_flags: PKT_RX_L4_CKSUM_UNKNOWN PKT_RX_IP_CKSUM_UNKNOWN PKT_RX_OUTER_L4_CKSUM_UNKNOWN

NIC没有对它发送的Tx数据包进行RX，为什么？

Answer 1

为了将DPDK应用程序dpdk-tespmd设置为环回模式，需要2 DPDK ports和--port-topology=loop。

但是，如果只有一个物理NIC端口，则有几个选项可以在回送模式下设置DPDK接口。

在fabric loopback mode

• if中配置了嵌入式交换机的TX和RX以及带有嵌入式交换机的cross-connected

• NIC连接到外部交换机，从而实现了交换机上的MAC|PHY loopback .

在上述3种模式中的任何一种模式下配置好后，运行以下命令

1. set -peer 0所需DST MAC地址
2. set fwd macswp
3. start tx_first

要在没有物理NIC测试the的情况下验证相同的./build/app/testpmd -l 2-3 --vdev=net_tap0,iface=testDpdk0 -- -i --rxq=1 --txq=1。设置RX数据包set verbose 2的详细信息